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{{Short description|Mental disorder with psychotic symptoms}}
{{Infobox_Disease |
{{Other uses}}
Name = Schizophrenia |
{{Pp|small=yes}}
Image = |
{{pp-move}}
Caption = |
{{Use dmy dates|date=March 2023}}
DiseasesDB = 11890 |
{{cs1 config|name-list-style=vanc|display-authors=6}}
ICD10 = {{ICD10|F|20||f|20}} |
{{Infobox medical condition
ICD9 = {{ICD9|295}} |
| name = Schizophrenia
ICDO = |
| image = Cloth embroidered by a schizophrenia sufferer.jpg
OMIM = 181500 |
| alt = Embroidery art with nonlinear text sewn into it with multiple colors of thread
MedlinePlus = |
| caption = Cloth ] by a person diagnosed with schizophrenia
eMedicineSubj = med |
| field = ]<ref>{{cite book | vauthors = Jones D | author-link = Daniel Jones (phonetician) | title = English Pronouncing Dictionary |veditors= Roach P, Hartmann J, Setter J |publisher=Cambridge University Press |orig-date=1917 |year=2003 | isbn = 978-3-12-539683-8}}</ref>
eMedicineTopic = 2072 |
| symptoms = ]s, ]s, ], ]<ref name=WHO2022/><ref name=NIH2022>{{cite web |title=Schizophrenia |work= Health topics |url=https://www.nimh.nih.gov/health/topics/schizophrenia/index.shtml |publisher= US ] |date=April 2022|access-date=22 August 2022}}</ref>
eMedicine_mult = {{eMedicine2|emerg|520}} |
| complications = Harm to self or others, social isolation, cognitive issues, ], ]s,<ref name=SBU2012>{{Cite web|url=http://www.sbu.se/en/publications/sbu-assesses/schizophrenia--pharmacological-treatments-patient-involvement-and-organization-of-care/|title=Medicinal treatment of psychosis/schizophrenia|date=21 November 2012 |publisher=] (SBU)|archive-url=https://web.archive.org/web/20170629092226/http://www.sbu.se/en/publications/sbu-assesses/schizophrenia--pharmacological-treatments-patient-involvement-and-organization-of-care/|archive-date=29 June 2017|url-status=live|access-date=26 June 2017}}</ref> ] and ] arising from ] medication<ref>{{cite web | vauthors = Proietto Sr J |title=Diabetes and Antipsychotic Drugs |url=https://www.medsafe.govt.nz/profs/puarticles/antipsychdiabetes.htm |publisher=] |date=November 2004}}</ref><ref>{{cite journal | vauthors = Holt RI | title = Association Between Antipsychotic Medication Use and Diabetes | journal = Current Diabetes Reports | volume = 19 | issue = 10 | pages = 96 | date = September 2019 | pmid = 31478094 | pmc = 6718373 | doi = 10.1007/s11892-019-1220-8 | publisher = ] |issn=1534-4827}}</ref>
MeshName = Schizophrenia |
| onset = Ages 16 to 30<ref name=NIH2022/>
MeshNumber = F03.700.750 |
| duration = Chronic<ref name=NIH2022/>
}}
| causes = Environmental and genetic factors<ref name=Lancet2016/>
<!--Para1: Definition and characterization-->
| risks = ], ] use in adolescence, ]- or ]-associated psychosis,<ref>{{cite journal |title=Transition of Substance-Induced, Brief, and Atypical Psychoses to Schizophrenia: A Systematic Review and Meta-analysis|url=https://academic.oup.com/schizophreniabulletin/article/46/3/505/5588638 |journal=] |date=May 2020}}</ref> problems during pregnancy, ], being born or raised in a city<ref name=Lancet2016/><ref>{{cite journal | vauthors = Gruebner O, Rapp MA, Adli M, Kluge U, Galea S, Heinz A | title = Cities and Mental Health | journal = Deutsches Ärzteblatt International | volume = 114 | issue = 8 | pages = 121–127 | date = February 2017 | pmid = 28302261 | pmc = 5374256 | doi = 10.3238/arztebl.2017.0121 }}</ref>
'''Schizophrenia''' (from the ] word σχιζοφρένεια, "split mind") is a psychiatric ] that describes a ] characterized by impairments in the ] or expression of ] and by significant social or occupational dysfunction. A person experiencing schizophrenia is typically characterized as demonstrating disorganized ], and as experiencing ]s or auditory ]s.
| diagnosis = Based on observed behavior, reported experiences, and reports of others familiar with the person<ref name=DSM5/>
| differential = ], ], ] (], ]), ],<ref name=Ferri2010>{{cite book|vauthors=Ferri FF |title=Ferri's differential diagnosis: a practical guide to the differential diagnosis of symptoms, signs, and clinical disorders |date=2010 |publisher=Elsevier/Mosby |location=Philadelphia |isbn=978-0-323-07699-9 |chapter=Chapter S |edition=2nd}}</ref> ],<ref name=Paris2018/> ], ], ], ], ], ], ], ]
| prevention =
| management = Counseling, ] training<ref name=WHO2022/><ref name=Lancet2016/>
| medication = ]<ref name=Lancet2016/>
| prognosis = 20–28 years shorter ]<ref name=Laursen2014/><ref name=NIHStat/>
| frequency = ~0.32% (1 in 300) of the global population is affected.<ref name=WHO_FACT_SHEET>{{cite web |title=Schizophrenia Fact Sheet and Information |url=https://www.who.int/news-room/fact-sheets/detail/schizophrenia |publisher=]}}</ref>
| deaths = ~17,000 (2015)<ref name=GBD2015/>
}}
<!-- Definition, symptoms, and diagnosis-->
'''Schizophrenia''' is a ]<ref>{{cite web |title=ICD-11: 6A20 Schizophrenia |url=https://icd.who.int/browse11/l-m/en#/http%3a%2f%2fid.who.int%2ficd%2fentity%2f1683919430 |publisher=] |access-date= 23 August 2022 }}</ref><ref name= Lancet2016/> characterized variously by ]s (typically, ]), ]s, ] and behavior,<ref name=DSM5/> and ].<ref name= Lancet2016/> Symptoms ] and typically begin during young adulthood and are never resolved.<ref name=NIH2022/><ref name=DSM5/> There is no objective diagnostic test; diagnosis is based on observed behavior, a ] that includes the person's reported experiences, and reports of others familiar with the person.<ref name=DSM5/> For a diagnosis of schizophrenia, the described symptoms need to have been present for at least six months (according to the ]) or one month (according to the ]).<ref name=DSM5>{{cite book |title=Diagnostic and Statistical Manual of Mental Disorders: DSM-5 |edition=5th |date=2013 |publisher=American Psychiatric Association |location=Arlington, VA |isbn=978-0-89042-555-8 |pages=99–105}}</ref><ref name=Ferri2019/> Many people with schizophrenia have other mental disorders, especially ]s, ]s, and ].<ref name=DSM5/>


<!-- Epidemiology and causes -->
Although the disorder is primarily thought to affect ], it can also contribute to chronic problems with ] and ]. Due to the many possible combinations of symptoms, heated debate is ongoing about whether the diagnosis necessarily or adequately describes a disorder, or alternatively whether it might represent a number of disorders. For this reason, ] deliberately called the disease "the schizophrenias" plural, when he coined the present name.
About 0.3% to 0.7% of people are diagnosed with schizophrenia during their lifetime.<ref name=Javitt2014>{{cite journal |vauthors=Javitt DC |title=Balancing therapeutic safety and efficacy to improve clinical and economic outcomes in schizophrenia: a clinical overview |journal=The American Journal of Managed Care |volume=20 |issue=8 Suppl |pages=S160-165 |date=June 2014 |pmid=25180705}}</ref> In 2017, there were an estimated 1.1&nbsp;million new cases and in 2022 a total of 24 million cases globally.<ref name=WHO2022/><ref name=GBD2018>{{cite journal |vauthors=James SL, Abate D |title=Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017 |journal=The Lancet |date=November 2018 |volume=392 |issue=10159 |pages=1789–1858 |doi=10.1016/S0140-6736(18)32279-7 |pmid=30496104 |pmc=6227754 }}</ref> Males are more often affected and on average have an earlier onset than females.<ref name=WHO2022>{{cite web |title=Schizophrenia Fact sheet | url = https://www.who.int/news-room/fact-sheets/detail/schizophrenia | publisher = ] | date = 10 January 2022 | access-date = 23 August 2022 }}</ref> The causes of schizophrenia may include ] and ] factors.<ref name=Lancet2016/> Genetic factors include a variety of common and rare ].<ref name=vandeLeemput2016>{{cite book|vauthors=van de Leemput J, Hess JL, Glatt SJ, Tsuang MT|date=2016|title=Genetics of Schizophrenia: Historical Insights and Prevailing Evidence |series=Advances in Genetics|volume=96|pages=99–141|doi=10.1016/bs.adgen.2016.08.001|pmid=27968732|isbn=978-0-12-809672-7 }}</ref> Possible environmental factors include ], childhood adversity, ] use during adolescence, infections, the ], and poor ].<ref name=Lancet2016/><ref name=Parakh2013/>


<!--Para2: Diagnosis and suspected causes--> <!-- Course and prognosis -->
About half of those diagnosed with schizophrenia will have a significant improvement over the long term with no further relapses, and a small proportion of these will recover completely.<ref name=DSM5/><!-- Quote: "The course appears to be favorable in about 20% of those with schizophrenia, and a small number of individuals are reported to recover completely." --><ref name=Vita2018>{{cite journal | vauthors = Vita A, Barlati S | s2cid = 35299996 | title = Recovery from schizophrenia: is it possible? | journal = Current Opinion in Psychiatry | date = May 2018 |volume = 31 | issue = 3 | pages = 246–255 | doi = 10.1097/YCO.0000000000000407 | pmid = 29474266}}</ref> The other half will have a lifelong impairment.<ref name=Law2015>{{cite book | vauthors= Lawrence RE, First MB, Lieberman JA | chapter = Chapter 48: Schizophrenia and Other Psychoses | veditors= Tasman A, Kay J, Lieberman JA, First MB, Riba MB | title = Psychiatry | edition = fourth | date = 2015 | pages = 798, 816, 819 | doi = 10.1002/9781118753378.ch48 | publisher=John Wiley & Sons, Ltd. | isbn = 978-1-118-84547-9 }}</ref> In severe cases, people may be admitted to hospitals.<ref name=Vita2018/> Social problems such as ], poverty, ], exploitation, and victimization are commonly correlated with schizophrenia.<ref name=Killaspy2014/><ref name=Charleson2018>{{cite journal | vauthors = Charlson FJ, Ferrari AJ, Santomauro DF, Diminic S, Stockings E, Scott JG, McGrath JJ, Whiteford HA | title = Global Epidemiology and Burden of Schizophrenia: Findings From the Global Burden of Disease Study 2016 | journal = Schizophrenia Bulletin | volume = 44 | issue = 6 | pages = 1195–1203 | date = October 2018 | pmid = 29762765 | pmc = 6192504 | doi = 10.1093/schbul/sby058 }}</ref> Compared to the general population, people with schizophrenia have a higher suicide rate (about 5% overall) and more ],<ref name=Lancet2009>{{cite journal | vauthors = ], ] | s2cid = 208792724 | title = Schizophrenia | journal = Lancet | volume = 374 | issue = 9690 | pages = 635–645 | date = August 2009 | pmid = 19700006 | doi = 10.1016/S0140-6736(09)60995-8 | url = http://xa.yimg.com/kq/groups/19525360/611943554/name/Schizophrenia+-+The+Lancet.pdf | archive-url = https://web.archive.org/web/20130623065810/http://xa.yimg.com/kq/groups/19525360/611943554/name/Schizophrenia+-+The+Lancet.pdf | df = dmy-all | archive-date = 23 June 2013 | access-date = 23 December 2011 }}</ref><ref name=Jop2010>{{cite journal | vauthors = Hor K, Taylor M | title = Suicide and schizophrenia: a systematic review of rates and risk factors | journal = Journal of Psychopharmacology | volume = 24 | issue = 4 Suppl | pages = 81–90 | date = November 2010 | pmid = 20923923 | pmc = 2951591 | doi = 10.1177/1359786810385490 }}</ref> leading to an average decrease in ] by 20<ref name=Laursen2014>{{cite journal | vauthors = Laursen TM, Nordentoft M, Mortensen PB | title = Excess early mortality in schizophrenia| journal = Annual Review of Clinical Psychology | date = 2014 | volume = 10 | pages=425–448 | doi = 10.1146/annurev-clinpsy-032813-153657 | pmid = 24313570| doi-access = free }}</ref> to 28 years.<ref name=NIHStat/> In 2015, an estimated 17,000 deaths were linked to schizophrenia.<ref name=GBD2015>{{cite journal | vauthors = Wang H, Naghavi M, Allen C, etal | collaboration = GBD 2015 Mortality and Causes of Death Collaborators | title = Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980–2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1459–1544 | date = October 2016 | pmid = 27733281 | pmc = 5388903 | doi = 10.1016/S0140-6736(16)31012-1 }}</ref>
Diagnosis is based on the self-reported experiences of the patient, in combination with secondary signs observed by a ], ] or other competent clinician. No objective ] test for schizophrenia exists, though studies suggest that ], ] and social environment are important contributing factors. Current research into the development of the disorder often focuses on the role of neurobiology, although a reliable and identifiable organic cause has not been found. In the absence of objective laboratory tests to confirm the diagnosis, some question the ] of schizophrenia's status as a ]. Furthermore, some question the status of schizophrenia as a disease on the basis that they do not consider the condition to be an impairment.


<!-- Treatment -->
<!--Para3: Tricky etymology and misconceptions-->
The mainstay of treatment is ] medication, including ] and ], along with ], job training, and ].<ref name=Lancet2016>{{cite journal | vauthors = Owen MJ, Sawa A, Mortensen PB | title = Schizophrenia | journal = The Lancet | volume = 388 | issue = 10039 | pages = 86–97 | date = July 2016 | pmid = 26777917 | pmc = 4940219 | doi = 10.1016/S0140-6736(15)01121-6 }}</ref> Up to a third of people do not respond to initial antipsychotics, in which case ] is offered.<ref name=Siskind2017>{{cite journal |vauthors=Siskind D, Siskind V, Kisely S |title=Clozapine Response Rates among People with Treatment-Resistant Schizophrenia: Data from a Systematic Review and Meta-Analysis |journal=Canadian Journal of Psychiatry |volume=62 |issue=11 |pages=772–777 |date=November 2017 |pmid=28655284|doi=10.1177/0706743717718167|pmc=5697625 }}</ref> In a network comparative meta-analysis of 15 antipsychotic drugs, clozapine was significantly more effective than all other drugs, although clozapine's heavily multimodal action may cause more significant side effects.<ref>{{cite journal | vauthors = Leucht S, Cipriani A, Spineli L, Mavridis D, Orey D, Richter F, Samara M, Barbui C, Engel RR, Geddes JR, Kissling W, Stapf MP, Lässig B, Salanti G, Davis JM | title = Comparative efficacy and tolerability of 15 antipsychotic drugs in schizophrenia: a multiple-treatments meta-analysis | journal = Lancet | volume = 382 | issue = 9896 | pages = 951–962 | date = September 2013 | pmid = 23810019 | doi = 10.1016/S0140-6736(13)60733-3 | s2cid = 32085212 }}</ref> In situations where doctors judge that there is a risk of harm to self or others, they may impose short ].<ref name=BeckerKilian2006>{{cite journal | vauthors = Becker T, Kilian R | title = Psychiatric services for people with severe mental illness across western Europe: what can be generalized from current knowledge about differences in provision, costs and outcomes of mental health care? | journal = Acta Psychiatrica Scandinavica. Supplementum | volume = 113 | issue = 429 | pages = 9–16 | year = 2006 | pmid = 16445476 | doi = 10.1111/j.1600-0447.2005.00711.x | s2cid = 34615961 }}</ref> Long-term hospitalization is used on a small number of people with severe schizophrenia.<ref name=Capdevielle2009>{{cite journal |vauthors=Capdevielle D, Boulenger JP, Villebrun D, Ritchie K |title=Durées d'hospitalisation des patients souffrant de schizophrénie: implication des systèmes de soin et conséquences médicoéconomiques |trans-title=Schizophrenic patients' length of stay: mental health care implication and medicoeconomic consequences |language=fr |journal=L'Encéphale |volume=35 |issue=4 |pages=394–399 |date=September 2009 |pmid=19748377 |doi=10.1016/j.encep.2008.11.005 }}</ref> In some countries where supportive services are limited or unavailable, long-term hospital stays are more common.<ref name=Narayan2012>{{cite journal | vauthors = Narayan KK, Kumar DS | title = Disability in a Group of Long-stay Patients with Schizophrenia: Experience from a Mental Hospital. | journal = Indian Journal of Psychological Medicine | date = January 2012 | volume = 34 | issue = 1 | pages = 70–75 | doi = 10.4103/0253-7176.96164 | pmid = 22661812| pmc = 3361848 | doi-access = free }}</ref>
The term ''schizophrenia'' translates roughly as "shattered mind," and comes from the ] σχίζω (''schizo'', "to split" or "to divide") and φρήν (''phrēn'', "]"). Despite its etymology, schizophrenia is not synonymous with ], also known as multiple personality disorder or "split personality"; in ] the two are often confused. Although schizophrenia often leads to social or occupational ], a predisposition toward aggressive behavior is little associated with the illness.
{{TOC limit}}


==Signs and symptoms==
<!--Para4: Comorbidity-->
], who had schizophrenia]]
Patients diagnosed with schizophrenia are highly likely to be diagnosed with other disorders. The lifetime ] of ] is typically around 40%. ] is also high with ], ], and social problems, and a generally decreased ] is also present. Patients diagnosed with schizophrenia typically live 10-12 years less than their healthy counterparts, owing to increased physical health problems and a high ] rate.
Schizophrenia is a ] characterized by significant alterations in ], thoughts, mood, and behavior.<ref name=NICE2014/> Symptoms are described in terms of ], negative, and ].<ref name=NIH2022/><ref>{{cite journal |vauthors=Stępnicki P, Kondej M, Kaczor AA |title=Current Concepts and Treatments of Schizophrenia |journal= Molecules|volume=23 |issue=8 |date=20 August 2018 |pmid=30127324|doi=10.3390/molecules23082087 |pmc=6222385 |page=2087|doi-access=free }}</ref> The positive symptoms of schizophrenia are the same for any ] and are sometimes referred to as psychotic symptoms. These may be present in any of the different psychoses and are often transient, making early diagnosis of schizophrenia problematic. Psychosis noted for the first time in a person who is later diagnosed with schizophrenia is referred to as a first-episode psychosis (FEP).<ref name=RAISE>{{cite web |title=RAISE Questions and Answers |url=https://www.nimh.nih.gov/health/topics/schizophrenia/raise/raise-questions-and-answers.shtml#4 |publisher= US ]|access-date=29 December 2019}}</ref><ref>{{cite journal | vauthors = Marshall M | title = Association between duration of untreated psychosis and outcome in cohorts of first-episode patients: a systematic review | journal = Archives of General Psychiatry | date = September 2005 | volume = 62 | issue = 9 | pages = 975–983 | doi = 10.1001/archpsyc.62.9.975 | pmid = 16143729| s2cid = 13504781 | doi-access = }}</ref>


===Positive symptoms===
==Overview==
Positive symptoms are those symptoms that are not normally experienced, but are present in people during a psychotic episode in schizophrenia, including ]s, ]s, and disorganized thoughts, speech and behavior or inappropriate affect, typically regarded as manifestations of psychosis.<ref name=RAISE/> Hallucinations occur at some point in the lifetimes of 80% of those with schizophrenia<ref name=Montagnese2021>{{cite journal |vauthors=Montagnese M, Leptourgos P, Fernyhough C, et al |title=A Review of Multimodal Hallucinations: Categorization, Assessment, Theoretical Perspectives, and Clinical Recommendations |journal=Schizophr Bull |volume=47 |issue=1 |pages=237–248 |date=January 2021 |pmid=32772114 |pmc=7825001 |doi=10.1093/schbul/sbaa101 }}</ref> and most commonly involve the sense of ] (most often ]), but can sometimes involve any of the other ]s such as ], ], ], and ].<ref>{{cite journal |vauthors=Császár N, Kapócs G, Bókkon I |s2cid=52813070 |title=A possible key role of vision in the development of schizophrenia |journal=Reviews in the Neurosciences |volume=30 |issue=4 |pages=359–379 |date=27 May 2019 |pmid=30244235 |doi=10.1515/revneuro-2018-0022|doi-broken-date=3 December 2024 }}</ref> The frequency of hallucinations involving multiple senses is double the rate of those involving only one sense.<ref name=Montagnese2021/> They are also typically related to the content of the delusional theme.<ref name=DSMIV>{{cite book | author = American Psychiatric Association. Task Force on DSM-IV. | year = 2000 | title = Diagnostic and statistical manual of mental disorders: DSM-IV-TR. | publisher = American Psychiatric Pub. | isbn = 978-0-89042-025-6 | pages = 299–304 }}</ref> ]s are ] or ] in nature. ] such as feeling that ] or that ], sometimes termed passivity phenomena, are also common.<ref name=Heinz2016>{{cite journal | vauthors = Heinz A, Voss M, Lawrie SM, Mishara A, Bauer M, Gallinat J, Juckel G, Lang U, Rapp M, Falkai P, Strik W, Krystal J, Abi-Dargham A, Galderisi S | title = Shall we really say goodbye to first rank symptoms? | journal = European Psychiatry | volume = 37 | pages = 8–13 | date = September 2016 | pmid = 27429167 | doi = 10.1016/j.eurpsy.2016.04.010 | s2cid = 13761854 }}</ref><ref name=NIH2022/> Positive symptoms generally respond well to medication<ref name=Lancet2016/> and become reduced over the course of the illness, perhaps linked to the age-related decline in dopamine activity.<ref name=DSM5/>
Schizophrenia is often described in terms of "positive" and "negative" symptoms. ''Positive symptoms'' include ]s, ] and ] and are typically regarded as manifestations of ]. ''Negative symptoms'' are so named because they are considered to be the loss or absence of normal traits or abilities, and include features such as flat, blunted or constricted ] and ], poverty of ] and lack of ]. Some models of schizophrenia include ] and planning difficulties in a third group, a "disorganization syndrome".


===Negative symptoms===
Additionally, ]s may be present. These may take the form of reduced or impaired psychological functions such as ], ], ], ] or ].
Negative symptoms are deficits of normal emotional responses, or of other thought processes. The five recognized domains of negative symptoms are: ] – showing flat expressions (monotone) or little emotion; ] – a poverty of speech; ] – an inability to feel pleasure; ] – the lack of desire to form relationships, and ] – a lack of motivation and ].<ref name=Adida2015>{{cite journal |vauthors=Adida M, Azorin JM, Belzeaux R, Fakra E |title= |journal=L'Encephale |volume=41 |issue=6 Suppl 1 |pages=6S15–17 |date=December 2015 |pmid=26776385 |doi=10.1016/S0013-7006(16)30004-5}}</ref><ref>{{cite journal |vauthors=Mach C, Dollfus S |title= |journal=L'Encephale |volume=42 |issue=2 |pages=165–171 |date=April 2016 |pmid=26923997 |doi=10.1016/j.encep.2015.12.020}}</ref> Avolition and anhedonia are seen as motivational deficits resulting from impaired reward processing.<ref>{{cite journal |vauthors=Waltz JA, Gold JM |title=Motivational Deficits in Schizophrenia and the Representation of Expected Value |journal=Current Topics in Behavioral Neurosciences |volume=27 |pages=375–410 |date=2016 |pmid=26370946 |doi=10.1007/7854_2015_385 |pmc=4792780 |isbn=978-3-319-26933-7 }}</ref><ref name=Husain2018>{{cite journal |vauthors=Husain M, Roiser JP |s2cid=49428707 |title=Neuroscience of apathy and anhedonia: a transdiagnostic approach. |journal=Nature Reviews. Neuroscience|volume=19 |issue=8 |pages=470–484 |date=August 2018 |pmid=29946157 |doi=10.1038/s41583-018-0029-9|url=https://ora.ox.ac.uk/objects/uuid:3e481f87-0ede-47dd-bdd8-2db78dfd3694 }}</ref> Reward is the main driver of motivation and this is mostly mediated by dopamine.<ref name=Husain2018/> It has been suggested that negative symptoms are multidimensional and they have been categorised into two subdomains of apathy or lack of motivation, and diminished expression.<ref name=Adida2015/><ref name=Galderisi2018>{{cite journal |vauthors=Galderisi S, Mucci A, Buchanan RW, Arango C |title=Negative symptoms of schizophrenia: new developments and unanswered research questions |journal=The Lancet. Psychiatry |volume=5 |issue=8 |pages=664–677 |date=August 2018 |pmid=29602739 |doi=10.1016/S2215-0366(18)30050-6 |s2cid=4483198 }}</ref> Apathy includes avolition, anhedonia, and social withdrawal; diminished expression includes blunt affect and alogia.<ref>{{cite journal |vauthors=Klaus F, Dorsaz O, Kaiser S |title= |journal=Revue médicale suisse |volume=14 |issue=619 |pages=1660–1664 |date=19 September 2018 |doi=10.53738/REVMED.2018.14.619.1660 |pmid=30230774|s2cid=246764656 }}</ref> Sometimes diminished expression is treated as both verbal and non-verbal.<ref>{{cite journal |vauthors=Batinic B |title=Cognitive Models of Positive and Negative Symptoms of Schizophrenia and Implications for Treatment. |journal=Psychiatria Danubina |volume=31 |issue=Suppl 2 |pages=181–184 |date=June 2019 |pmid=31158119}}</ref>


Apathy accounts for around 50% of the most often found negative symptoms and affects functional outcome and subsequent quality of life. Apathy is related to disrupted cognitive processing affecting memory and planning including goal-directed behaviour.<ref>{{cite journal |vauthors=Bortolon C, Macgregor A, Capdevielle D, Raffard S |s2cid=13411386 |title=Apathy in schizophrenia: A review of neuropsychological and neuroanatomical studies. |journal=Neuropsychologia |volume=118 |issue=Pt B |pages=22–33 |date=September 2018 |pmid=28966139 |doi=10.1016/j.neuropsychologia.2017.09.033}}</ref> The two subdomains have suggested a need for separate treatment approaches.<ref name=Marder2014>{{cite journal |vauthors=Marder SR, Kirkpatrick B |s2cid=5172022 |title=Defining and measuring negative symptoms of schizophrenia in clinical trials |journal=European Neuropsychopharmacology|volume=24 |issue=5 |pages=737–743 |date=May 2014 |pmid=24275698 |doi=10.1016/j.euroneuro.2013.10.016}}</ref> A lack of distress is another noted negative symptom.<ref name=Tatsumi2020>{{cite journal |vauthors=Tatsumi K, Kirkpatrick B, Strauss GP, Opler M |s2cid=211141678 |title=The brief negative symptom scale in translation: A review of psychometric properties and beyond |journal=European Neuropsychopharmacology |date=April 2020 |volume=33 |pages=36–44 |doi=10.1016/j.euroneuro.2020.01.018 |pmid=32081498}}</ref> A distinction is often made between those negative symptoms that are inherent to schizophrenia, termed primary; and those that result from positive symptoms, from the side effects of antipsychotics, substance use disorder, and social deprivation – termed secondary negative symptoms.<ref>{{cite journal |vauthors=Klaus F, Kaiser S, Kirschner M |title=. |journal=Therapeutische Umschau |volume=75 |issue=1 |pages=51–56 |date=June 2018 |pmid=29909762 |doi=10.1024/0040-5930/a000966|s2cid=196502392 }}</ref> Negative symptoms are less responsive to medication and the most difficult to treat.<ref name=Marder2014/> However, if properly assessed, secondary negative symptoms are amenable to treatment.<ref name=Galderisi2018/> There is some evidence that the negative symptoms of schizophrenia are amenable to psychostimulant medication, although such drugs have varying degrees of risk for causing positive psychotic symptoms.<ref>{{Cite journal |last1=Lindenmayer |first1=Jean-Pierre |last2=Nasrallah |first2=Henry |last3=Pucci |first3=Michael |last4=James |first4=Steven |last5=Citrome |first5=Leslie |date=2013-07-01 |title=A systematic review of psychostimulant treatment of negative symptoms of schizophrenia: Challenges and therapeutic opportunities |url=https://www.sciencedirect.com/science/article/abs/pii/S0920996413001655 |journal=Schizophrenia Research |volume=147 |issue=2 |pages=241–252 |doi=10.1016/j.schres.2013.03.019 |pmid=23619055 |issn=0920-9964}}</ref>
Onset of schizophrenia typically occurs in late adolescence or early adulthood, with males tending to show symptoms earlier than females.


Scales for specifically assessing the presence of negative symptoms, and for measuring their severity, and their changes have been introduced since the earlier scales such as the ] that deals with all types of symptoms.<ref name=Marder2014/> These scales are the ''Clinical Assessment Interview for Negative Symptoms'' (CAINS), and the ''Brief Negative Symptom Scale'' (BNSS) also known as second-generation scales.<ref name=Marder2014/><ref name=Tatsumi2020/><ref>{{cite journal |vauthors=Wójciak P, Rybakowski J |title=Clinical picture, pathogenesis and psychometric assessment of negative symptoms of schizophrenia. |journal=Psychiatria Polska |volume=52 |issue=2 |pages=185–197 |date=30 April 2018 |pmid=29975360 |doi=10.12740/PP/70610|doi-access=free }}</ref> In 2020, ten years after its introduction, a cross-cultural study of the use of BNSS found valid and reliable ] evidence for its five-domain structure cross-culturally. The BNSS can assess both the presence and severity of negative symptoms of the five recognized domains and an additional item of reduced normal distress. It has been used to measure changes in negative symptoms in trials of psychosocial and pharmacological interventions.<ref name=Tatsumi2020/>
In 1893 ] ] was the first to draw a distinction between what he termed ] ("premature dementia") and other psychotic illnesses. In 1908, ''"dementia praecox"'' was renamed "schizophrenia" by psychiatrist ], who discovered that the disorder is not a form of ].


===Cognitive symptoms===
The diagnostic category of schizophrenia has been widely criticised as lacking in scientific validity or reliability, consistent with evidence of poor levels of consistency in diagnostic practices and the use of criteria. One alternative suggests that the problems and issues making up the diagnosis of schizophrenia would be better addressed as individual dimensions along which everyone varies, such that there is a spectrum or continuum rather than a cut-off between normal and ill. This approach appears consistent with research on ] and of a relatively high prevalence of psychotic experiences and delusional beliefs amongst the general public.
{{See also |Visual processing abnormalities in schizophrenia}}
] throughout the human brain in a patient with schizophrenia. The most deficient areas are magenta, while the least deficient areas are blue.]]
An estimated 70% of those with schizophrenia have cognitive deficits, and these are most pronounced in early-onset and late-onset illness.<ref name=Murante2017/><ref name=Kar2016>{{cite journal |vauthors=Kar SK, Jain M |title=Current understandings about cognition and the neurobiological correlates in schizophrenia |journal=Journal of Neurosciences in Rural Practice |volume=7 |issue=3 |pages=412–418 |date=July 2016 |pmid=27365960 |doi=10.4103/0976-3147.176185 |pmc=4898111 |doi-access=free }}</ref> These are often evident long before the onset of illness in the ], and may be present in childhood or early adolescence.<ref name=Bozikas2011/><ref>{{cite journal | vauthors = Shah JN, Qureshi SU, Jawaid A, Schulz PE | s2cid = 10970088 | title = Is there evidence for late cognitive decline in chronic schizophrenia? | journal = The Psychiatric Quarterly | volume = 83 | issue = 2 | pages = 127–144 | date = June 2012 | pmid = 21863346 | doi = 10.1007/s11126-011-9189-8 }}</ref> They are a core feature but not considered to be core symptoms, as are positive and negative symptoms.<ref name=Biedermann2016>{{cite journal |vauthors = Biedermann F, Fleischhacker WW | title = Psychotic disorders in DSM-5 and ICD-11 | journal = CNS Spectrums | date = August 2016 | volume = 21 | issue = 4 | pages = 349–354 | doi = 10.1017/S1092852916000316 | pmid = 27418328| s2cid = 24728447 }}</ref><ref name=Vidailhet2013/> However, their presence and degree of dysfunction is taken as a better indicator of functionality than the presentation of core symptoms.<ref name=Bozikas2011>{{cite journal | vauthors = Bozikas VP, Andreou C | s2cid = 26135485 | title = Longitudinal studies of cognition in first episode psychosis: a systematic review of the literature | journal = The Australian and New Zealand Journal of Psychiatry | volume = 45 | issue = 2 | pages = 93–108 | date = February 2011 | pmid = 21320033 | doi = 10.3109/00048674.2010.541418 }}</ref> Cognitive deficits become worse at first episode psychosis but then return to baseline, and remain fairly stable over the course of the illness.<ref name=Hashimoto2019/><ref name=Green2019/>


The deficits in ] are seen to drive the negative psychosocial outcome in schizophrenia, and are claimed{{By whom|date=March 2024}} to equate to a possible reduction in IQ from the norm of 100 to 70–85.<ref>{{cite journal | vauthors=Javitt DC, Sweet RA |title=Auditory dysfunction in schizophrenia: integrating clinical and basic features. |journal=Nature Reviews. Neuroscience|volume=16 |issue=9 |pages=535–550 |date=September 2015|pmid=26289573|doi=10.1038/nrn4002|pmc=4692466 }}</ref><ref name=Megreya2016>{{cite journal |vauthors=Megreya AM |s2cid=26125559 |title=Face perception in schizophrenia: a specific deficit |journal=Cognitive Neuropsychiatry |volume=21 |issue=1 |pages=60–72 |date=2016 |pmid=26816133|doi=10.1080/13546805.2015.1133407}}</ref> Cognitive deficits may be of ] (nonsocial) or of ].<ref name=Murante2017>{{cite journal |vauthors=Murante T, Cohen CI |title=Cognitive Functioning in Older Adults With Schizophrenia |journal=Focus (American Psychiatric Publishing) |volume=15 |issue=1 |pages=26–34 |date=January 2017 |pmid=31975837 |doi=10.1176/appi.focus.20160032|pmc=6519630 }}</ref> Neurocognition is the ability to receive and remember information, and includes verbal fluency, ], ]ing, ], ], and ] and visual perception.<ref name=Green2019/> ] and attention are seen to be the most affected.<ref name=Megreya2016/><ref>{{cite journal |vauthors=Eack SM |title=Cognitive remediation: a new generation of psychosocial interventions for people with schizophrenia |journal=Social Work |volume=57 |issue=3 |pages=235–246 |date=July 2012 |pmid=23252315 |doi=10.1093/sw/sws008|pmc=3683242 }}</ref> Verbal memory impairment is associated with a decreased level of ] (relating meaning to words).<ref>{{cite journal
Although no common cause of schizophrenia has been identified in all individuals diagnosed with the condition, currently most researchers and clinicians believe it results from a combination of both ] vulnerabilities (either inherited or acquired) and stressful life-events. This widely-adopted approach is known as the 'stress-vulnerability' model, and much scientific debate now focuses on how much each of these factors contributes to the development and maintenance of schizophrenia.
|vauthors=Pomarol-Clotet E, Oh M, Laws KR, McKenna PJ | title=Semantic priming in schizophrenia: systematic review and meta-analysis |journal=The British Journal of Psychiatry |volume=192 |issue=2 | pages=92–97 |date=February 2008 |pmid=18245021 |doi=10.1192/bjp.bp.106.032102 | hdl=2299/2735 |doi-access=free |hdl-access=free }}</ref> Another memory impairment is that of ].<ref>{{cite journal | vauthors = Goldberg TE, Keefe RS, Goldman RS, Robinson DG, Harvey PD | title = Circumstances under which practice does not make perfect: a review of the practice effect literature in schizophrenia and its relevance to clinical treatment studies | journal = Neuropsychopharmacology | volume = 35 | issue = 5 | pages = 1053–1062 | date = April 2010 | pmid = 20090669 | pmc = 3055399 | doi = 10.1038/npp.2009.211 | df = dmy-all }}</ref> An impairment in visual perception that is consistently found in schizophrenia is that of ].<ref name=Green2019/> ] impairments include an inability to perceive complex ]s.<ref>{{cite journal |vauthors=King DJ, Hodgekins J, Chouinard PA, Chouinard VA, Sperandio I |title=A review of abnormalities in the perception of visual illusions in schizophrenia. |journal=Psychonomic Bulletin and Review |volume=24 |issue=3 |pages=734–751 |date=June 2017 |pmid=27730532 |doi=10.3758/s13423-016-1168-5 |pmc = 5486866}}</ref> Social cognition is concerned with the mental operations needed to interpret, and understand the self and others in the social world.<ref name=Green2019>{{cite journal |vauthors=Green MF, Horan WP, Lee J |title=Nonsocial and social cognition in schizophrenia: current evidence and future directions |journal=World Psychiatry|volume=18 |issue=2 |pages=146–161 |date=June 2019 |pmid=31059632 |doi=10.1002/wps.20624|pmc=6502429 }}</ref><ref name=Murante2017/> This is also an associated impairment, and ] is often found to be difficult.<ref>{{cite journal | vauthors = Kohler CG, Walker JB, Martin EA, Healey KM, Moberg PJ | title = Facial emotion perception in schizophrenia: a meta-analytic review | journal = Schizophrenia Bulletin | volume = 36 | issue = 5 | pages = 1009–1019 | date = September 2010 | pmid = 19329561 | pmc = 2930336 | doi = 10.1093/schbul/sbn192 | df = dmy-all }}</ref><ref>{{cite journal | vauthors = Le Gall E, Iakimova G | title = | journal = L'Encéphale | volume = 44 | issue = 6 | pages = 523–537 | date = December 2018 | pmid = 30122298 | doi = 10.1016/j.encep.2018.03.004 | s2cid = 150099236 }}</ref> Facial perception is critical for ordinary social interaction.<ref>{{cite journal | vauthors = Grill-Spector K, Weiner KS, Kay K, Gomez J | title = The Functional Neuroanatomy of Human Face Perception | journal = Annual Review of Vision Science | volume = 3 | pages = 167–196 | date = September 2017 | pmid = 28715955 | pmc = 6345578 | doi = 10.1146/annurev-vision-102016-061214 }}</ref> Cognitive impairments do not usually respond to antipsychotics, and there are a number of ] that are used to try to improve them; ] is of particular help.<ref name=Vidailhet2013/>


] of clumsiness and loss of fine motor movement are often found in schizophrenia, which may resolve with effective treatment of FEP.<ref name=Ferri2019/><ref>{{cite journal |vauthors=Fountoulakis KN, Panagiotidis P, Kimiskidis V, Nimatoudis I, Gonda X |s2cid=56476015 |title=Neurological soft signs in familial and sporadic schizophrenia |journal=Psychiatry Research |volume=272 |pages=222–229 |date=February 2019 |pmid=30590276 |doi=10.1016/j.psychres.2018.12.105 }}</ref>
It is also thought that processes in early ] are important, particularly ] processes. In adult life, particular importance has been placed upon the function (or malfunction) of ] in the ] in the brain. This theory, known as the ] largely resulted from the accidental finding that a ] group which blocks dopamine function, known as the ]s, reduced psychotic symptoms. However, this theory is now thought to be overly simplistic as a complete explanation. These drugs have now been developed further and ] ] is commonly used as a first-line treatment. Although effective in many cases, these medications are not well tolerated by some patients due to significant ]. The positive symptoms are more responsive to medications; negative symptoms being less so.


===Onset===
Differences in brain structure have been found between people with schizophrenia and those without. However, these tend only to be reliable on the group level and, due to the significant variability between individuals, may not be reliably present in any particular individual.Significant brain atrophy and enlarged ventricles being the most conspicuous.
{{Further|Basic symptoms of schizophrenia}}
{{See also|Childhood schizophrenia|Adolescence#Changes in the brain}}
Onset typically occurs between the late teens and early 30s, with the peak incidence occurring in males in the early to mid-twenties, and in females in the late twenties.<ref name=NIH2022/><ref name=DSM5/><ref name=Ferri2019/> Onset before the age of 17 is known as early-onset,<ref>{{cite journal |vauthors=Bourgou Gaha S, Halayem Dhouib S, Amado I, Bouden A |title= |journal=L'Encephale |volume=41 |issue=3 |pages=209–214 |date=June 2015 |pmid=24854724 |doi=10.1016/j.encep.2014.01.005}}</ref> and before the age of 13, as can sometimes occur, is known as ] or very early-onset.<ref name=DSM5 /><ref name=DaFonseca2018>{{cite journal |vauthors=Da Fonseca D, Fourneret P |title= |journal=L'Encephale |volume=44 |issue=6S |pages=S8–S11 |date=December 2018 |pmid=30935493 |doi=10.1016/S0013-7006(19)30071-5|s2cid=150798223 }}</ref> Onset can occur between the ages of 40 and 60, known as late-onset schizophrenia.<ref name=Murante2017/> Onset over the age of 60, which may be difficult to differentiate as schizophrenia, is known as very-late-onset schizophrenia-like psychosis.<ref name=Murante2017/> Late onset has shown that a higher rate of females are affected; they have less severe symptoms and need lower doses of antipsychotics.<ref name=Murante2017/> The tendency for earlier onset in males is later seen to be balanced by a ] increase in the development in females. ] produced pre-menopause has a dampening effect on dopamine receptors but its protection can be overridden by a genetic overload.<ref>{{cite journal |vauthors=Häfner H |title=From Onset and Prodromal Stage to a Life-Long Course of Schizophrenia and Its Symptom Dimensions: How Sex, Age, and Other Risk Factors Influence Incidence and Course of Illness |journal=Psychiatry Journal |volume=2019 |page=9804836 |date=2019 |pmid=31139639 |doi=10.1155/2019/9804836 |pmc=6500669 |doi-access=free }}</ref> There has been a dramatic increase in the numbers of older adults with schizophrenia.<ref>{{cite journal | vauthors = Cohen CI, Freeman K, Ghoneim D, Vengassery A, Ghezelaiagh B, Reinhardt MM | title = Advances in the Conceptualization and Study of Schizophrenia in Later Life | journal = The Psychiatric Clinics of North America | volume = 41 | issue = 1 | pages = 39–53 | date = March 2018 | pmid = 29412847 | doi = 10.1016/j.psc.2017.10.004 }}</ref>


Onset may happen suddenly or may occur after the slow and gradual development of a number of signs and symptoms, a period known as the ].<ref name=DSM5 /> Up to 75% of those with schizophrenia go through a prodromal stage.<ref name=George2017>{{cite journal |vauthors=George M, Maheshwari S, Chandran S, Manohar JS, Sathyanarayana Rao TS |title=Understanding the schizophrenia prodrome |journal=Indian Journal of Psychiatry |volume=59 |issue=4 |pages=505–509 |date=October 2017 |pmid=29497198 |doi=10.4103/psychiatry.IndianJPsychiatry_464_17|doi-broken-date=1 November 2024 |doi-access=free|pmc=5806335 }}</ref> The negative and cognitive symptoms in the prodrome stage can precede FEP (first episode psychosis) by many months and up to five years.<ref name=Hashimoto2019>{{cite journal |vauthors=Hashimoto K |s2cid=195814019 |title=Recent Advances in the Early Intervention in Schizophrenia: Future Direction from Preclinical Findings |journal=Current Psychiatry Reports |volume=21 |issue=8 |page=75 |date=5 July 2019 |pmid=31278495 |doi=10.1007/s11920-019-1063-7}}</ref><ref name=Conroy2018>{{cite journal |vauthors=Conroy S, Francis M, Hulvershorn LA |title=Identifying and treating the prodromal phases of bipolar disorder and schizophrenia |journal=Current Treatment Options in Psychiatry |volume=5 |issue=1 |pages=113–128 |date=March 2018 |pmid=30364516 |doi=10.1007/s40501-018-0138-0|pmc=6196741 }}</ref> The period from FEP and treatment is known as the duration of untreated psychosis (DUP) which is seen to be a factor in functional outcome. The prodromal stage is the high-risk stage for the development of psychosis.<ref name=Green2019/> Since the progression to first episode psychosis is not inevitable, an alternative term is often preferred of ].<ref name=Green2019/> Cognitive dysfunction at an early age impacts a young person's usual cognitive development.<ref>{{cite journal |vauthors=Lecardeur L, Meunier-Cussac S, Dollfus S |title= |journal=L'Encephale |volume=39 |pages=S64-71 |date=May 2013 |issue=Suppl 1 |pmid=23528322 |doi=10.1016/j.encep.2012.10.011}}</ref> Recognition and early intervention at the prodromal stage would minimize the associated disruption to educational and social development and has been the focus of many studies.<ref name=Hashimoto2019/><ref name=Conroy2018/>
==History==
Accounts that may relate to symptoms of schizophrenia date back as far as 2000 BC in the ''Book of Hearts'', part of the ancient ]. However, a recent study<ref name="fn_1"> Searching for schizophrenia in ancient Greek and Roman literature: a ]. ''Acta Psychiatrica Scandanavica'', 107(5), 323&ndash;330.<br></ref> into the ] and ] literature showed that, while the general population probably had an awareness of psychotic disorders, there was no recorded condition that would meet the modern diagnostic criteria for schizophrenia in these societies.


==Risk factors==
This nonspecific concept of "]" has been around for many thousands of years, but schizophrenia was only classified as a distinct mental disorder by Kraepelin in 1893. He was the first to make a distinction in the psychotic disorders between what he called ''dementia praecox'' (a term first used by psychiatrist ]) and ]. Kraepelin believed that dementia praecox was primarily a disease of the brain<ref name="fn_2">Kraepelin, E. (1907) ''Text book of psychiatry (7th ed)'' (trans. A.R. Diefendorf). London: Macmillan.<br></ref>, and particularly a form of ]. Kraepelin named the disorder 'dementia praecox' (early dementia) to distinguish it from other forms of dementia (such as ]) which typically occur late in life. He used this term because his studies focused on young adults with dementia.<ref name="fn_49">"''Conditions in Occupational Therapy: effect on occupational performance.''" ed. Ruth A. Hansen and Ben Atchison (Baltimore: Lippincott Williams & Williams, 2000), 54&ndash;74. ISBN 0-683-30417-8<br></ref>
{{Main|Risk factors of schizophrenia}}
Schizophrenia is described as a ] with no precise boundary, or single cause, and is thought to develop from ]s with involved vulnerability factors.<ref name=Lancet2016/><ref>{{cite journal | vauthors = Mullin AP, Gokhale A, Moreno-De-Luca A, Sanyal S, Waddington JL, Faundez V | title = Neurodevelopmental disorders: mechanisms and boundary definitions from genomes, interactomes and proteomes | journal = Translational Psychiatry | volume = 3 | issue = 12 | pages = e329 | date = December 2013 | pmid = 24301647 | pmc = 4030327 | doi = 10.1038/tp.2013.108 }}</ref><ref name= Davis2016/> The interactions of these ]s are complex, as numerous and diverse ] from conception to adulthood can be involved.<ref name=Davis2016>{{cite journal | vauthors = Davis J, Eyre H, Jacka FN, Dodd S, Dean O, McEwen S, Debnath M, McGrath J, Maes M, Amminger P, McGorry PD, Pantelis C, Berk M | title = A review of vulnerability and risks for schizophrenia: Beyond the two hit hypothesis | journal = Neuroscience and Biobehavioral Reviews | volume = 65 | pages = 185–194 | date = June 2016 | pmid = 27073049 | pmc = 4876729 | doi = 10.1016/j.neubiorev.2016.03.017 }}</ref> A genetic predisposition on its own, without interacting environmental factors, will not give rise to the development of schizophrenia.<ref name=Davis2016/><ref name=Perkovic2017>{{cite journal | vauthors = Perkovic MN, Erjavec GN, Strac DS, Uzun S, Kozumplik O, Pivac N | title = Theranostic Biomarkers for Schizophrenia | journal = International Journal of Molecular Sciences | volume = 18 | issue = 4 | page = 733 | date = March 2017 | pmid = 28358316 | pmc = 5412319 | doi = 10.3390/ijms18040733 | doi-access = free }}</ref> The genetic component means that ] brain development is disturbed, and environmental influence affects the postnatal development of the brain.<ref name= Suvisaari2010>{{cite journal | vauthors = Suvisaari J | title = | language = Finnish | journal = Duodecim; Laaketieteellinen Aikakauskirja | volume = 126 | issue = 8 | pages = 869–876 | date = 2010 | pmid = 20597333 }}</ref> Evidence suggests that genetically susceptible children are more likely to be vulnerable to the effects of environmental risk factors.<ref name= Suvisaari2010/>


===Genetic===
The term ''schizophrenia'' is derived from the Greek words σχίζειν (split) and φρήν (mind) and was coined by ] in 1908 to refer to the lack of interaction between thought processes and ]. He was also the first to describe the symptoms as "positive" or "negative."<ref name="fn_2" /> Blueler described the main symptoms as 4 "A"'s: flattened Affect, Autism, impaired Association of ideas and Ambivalence. <ref name="fn_78"> Epistemological aspects of Eugen Bleuler's conception of schizophrenia in 1911. ''Medicine, Health Care, and Philosophy'', 3(2), 153-9.<br></ref> Bleuler suggested the name schizophrenia, as it was obvious that Kraepelin's name was misleading. The word "praecox" implied precocious or early onset, hence premature dementia, as opposed to ] from old age. Bleuler realized the illness was not a dementia as some of his patients improved rather than following a deteriorating course.
Estimates of the ] of schizophrenia are between 70% and 80%, which implies that 70% to 80% of the individual differences in risk of schizophrenia are associated with genetics.<ref name=vandeLeemput2016/><ref name=Her2011/> These estimates vary because of the ] genetic and environmental influences, and their accuracy has been queried.<ref>{{cite journal | vauthors = O'Donovan MC, Williams NM, Owen MJ | title = Recent advances in the genetics of schizophrenia | journal = Human Molecular Genetics | volume = 12 Spec No 2 | pages = R125–133 | date = October 2003 | pmid = 12952866 | doi = 10.1093/hmg/ddg302 | doi-access = free }}</ref><ref name=Torrey2019>{{Cite journal |vauthors=Torrey EF, Yolken RH |s2cid=173991937 |date=August 2019 |title=Schizophrenia as a pseudogenetic disease: A call for more gene-environmental studies |journal=Psychiatry Research |volume=278 |pages=146–150 |doi=10.1016/j.psychres.2019.06.006|pmid=31200193 }}</ref> The greatest risk factor for developing schizophrenia is having a ] with the disease (risk is 6.5%); more than 40% of ] of those with schizophrenia are also affected.<ref name=BMJ07>{{cite journal | vauthors = Picchioni MM, Murray RM | title = Schizophrenia | journal = BMJ | volume = 335 | issue = 7610 | pages = 91–95 | date = July 2007 | pmid = 17626963 | pmc = 1914490 | doi = 10.1136/bmj.39227.616447.BE }}</ref> If one parent is affected the risk is about 13% and if both are affected the risk is nearly 50%.<ref name=Her2011>{{cite book|title=Adult psychopathology and diagnosis |year=2011 |publisher=John Wiley & Sons |isbn=978-1-118-13884-7 |chapter-url= https://books.google.com/books?id=iJtzm1KfU5oC&pg=PT282 |chapter= Chapter 8: Schizophrenia: Etiological considerations| veditors = Hersen M, Beidel DC |edition=6th| vauthors = Combs DR, Mueser KT, Gutierrez MM }}</ref> However, the ''DSM-5'' indicates that most people with schizophrenia have no family history of psychosis.<ref name=DSM5/> Results of ] studies of schizophrenia have generally failed to find consistent associations,<ref>{{cite journal | vauthors = Farrell MS, Werge T, Sklar P, Owen MJ, Ophoff RA, O'Donovan MC, Corvin A, Cichon S, Sullivan PF | title = Evaluating historical candidate genes for schizophrenia | journal = Molecular Psychiatry | volume = 20 | issue = 5 | pages = 555–562 | date = May 2015 | pmid = 25754081 | pmc = 4414705 | doi = 10.1038/mp.2015.16 }}</ref> and the ] identified by ] explain only a small fraction of the variation in the disease.<ref>{{Cite book |url= https://books.google.com/books?id=7ukmDAAAQBAJ |title=Schizophrenia and Psychotic Spectrum Disorders | vauthors = Schulz SC, Green MF, Nelson KJ |date=2016 |publisher=Oxford University Press |isbn=9780199378067 |pages=124–125 }}</ref>


Many ] are known to be involved in schizophrenia, each with small effects and unknown ] and ].<ref name=vandeLeemput2016/><ref>{{cite journal | vauthors = Schork AJ, Wang Y, Thompson WK, Dale AM, Andreassen OA | title = New statistical approaches exploit the polygenic architecture of schizophrenia—implications for the underlying neurobiology | journal = Current Opinion in Neurobiology | volume = 36 | pages = 89–98 | date = February 2016 | pmid = 26555806 | pmc = 5380793 | doi = 10.1016/j.conb.2015.10.008 }}</ref><ref>{{cite journal|vauthors= Coelewij L, Curtis D|title=Mini-review: Update on the genetics of schizophrenia|journal=Annals of Human Genetics|volume=82|issue=5|year= 2018|pages=239–243|issn=0003-4800|doi=10.1111/ahg.12259|pmid= 29923609|s2cid=49311660|url=https://discovery.ucl.ac.uk/id/eprint/10064654/ |doi-access=free}}</ref> The summation of these effect sizes into a ] can explain at least 7% of the variability in liability for schizophrenia.<ref>{{cite journal | vauthors = Kendler KS | title = The Schizophrenia Polygenic Risk Score: To What Does It Predispose in Adolescence? | journal = JAMA Psychiatry | volume = 73 | issue = 3 | pages = 193–194 | date = March 2016 | pmid = 26817666 | doi = 10.1001/jamapsychiatry.2015.2964 }}</ref> Around 5% of cases of schizophrenia are understood to be at least partially attributable to rare ]s (CNVs); these ]s are associated with known genomic disorders involving ] at ] (]) and ] (]), duplications at ] (most frequently found) and deletions at ] (]).<ref name=Lowther2017p82>{{cite journal | vauthors = Lowther C, Costain G, Baribeau DA, Bassett AS | s2cid = 4776174 | title = Genomic Disorders in Psychiatry—What Does the Clinician Need to Know? | journal = Current Psychiatry Reports | volume = 19 | issue = 11 | page = 82 | date = September 2017 | doi = 10.1007/s11920-017-0831-5 | pmid = 28929285 }}</ref> Some of these CNVs increase the risk of developing schizophrenia by as much as 20-fold, and are frequently comorbid with autism and intellectual disabilities.<ref name=Lowther2017p82/>
With the name 'schizophrenia' Bleuler intended to capture the separation of function between ], ], ], and ], however it is commonly misunderstood to mean that affected persons have a 'split personality' (something akin to the character in ] '']''). Although some people diagnosed with schizophrenia may hear voices and may experience the voices as distinct personalities, schizophrenia does not involve a person changing among distinct multiple personalities. The confusion perhaps arises in part due to the meaning of Bleuler's term 'schizophrenia' (literally 'split' or 'shattered mind'). Interestingly, the first known misuse of this word schizophrenia to mean 'split personality' (in the ] sense) was in an article by the poet ] in 1933.<ref name="fn_3">Turner, T. (1999) 'Schizophrenia'. In G.E. Berrios and R. Porter (eds) ''A History of Clinical Psychiatry''. London: Athlone Press. ISBN 0-485-24211-7<br></ref>


The genes ] and ] are associated with the severity of suicidal behavior. These genes code for stress response proteins needed in the control of the ], and their interaction can affect this axis. Response to stress can cause lasting changes in the ] possibly disrupting the negative feedback mechanism, ], and the regulation of emotion leading to altered behaviors.<ref name=Perkovic2017/>
In the first half of the ] schizophrenia was considered by many to be a "hereditary defect", and individuals affected by schizophrenia became subject to ] in many countries. Hundreds of thousands were ], with or without consent, the majority in ], the ], and ] countries.<ref name="fn_76"> The social and economic origins of genetic determinism: a case history of the American Eugenics Movement, 1900-1940 and its lessons for today. ''Genetica'', 99, 77-88.<br></ref>,<ref name="fn_77">Read, J., Masson, J. (2004) Genetics, eugenics and mass murder. In J. Read, L.R. Mosher, R.P. Bentall (eds) ''Models of Madness: Psychological, Social and Biological Approaches to Schizophrenia''. ISBN 1-58391-906-6<br></ref> Many people diagnosed with schizophrenia, together with other people labeled "mentally unfit", were murdered in the Nazi "]" program.


The question of how schizophrenia could be primarily genetically influenced, given that people with schizophrenia have lower fertility rates, is a paradox. It is expected that ] that increase the risk of schizophrenia would be selected against, due to their negative effects on ]. A number of potential explanations have been proposed, including that ]s associated with schizophrenia risk confers a fitness advantage in unaffected individuals.<ref>{{Cite journal |vauthors= Bundy H, Stahl D, MacCabe JH |date=February 2011 |title=A systematic review and meta-analysis of the fertility of patients with schizophrenia and their unaffected relatives: Fertility in schizophrenia |journal=Acta Psychiatrica Scandinavica |volume=123 |issue=2 |pages=98–106 |doi= 10.1111/j.1600-0447.2010.01623.x|pmid=20958271 |s2cid=45179016 }}</ref><ref>{{Cite journal |vauthors= van Dongen J, Boomsma DI |date=March 2013 |title=The evolutionary paradox and the missing heritability of schizophrenia |journal=American Journal of Medical Genetics Part B: Neuropsychiatric Genetics |volume=162 |issue=2 |pages=122–136 |doi= 10.1002/ajmg.b.32135|pmid=23355297 |s2cid=9648115 }}</ref> While some evidence has not supported this idea,<ref name=Torrey2019/> others propose that a large number of alleles each contributing a small amount can persist.<ref>{{cite journal |vauthors= Owen MJ, Sawa A, Mortensen PB |title=Schizophrenia |journal=Lancet |date=2 July 2016 |volume=388 |issue=10039 |pages=86–97 |doi=10.1016/S0140-6736(15)01121-6 |pmid= 26777917|pmc=4940219}}</ref>
==Diagnosis==
===Criteria (signs and symptoms) ===
Like many mental illnesses, the diagnosis of schizophrenia is based upon the behavior of the person being assessed. There is a list of criteria that must be met for someone to be so diagnosed. These depend on both the presence and duration of certain signs and symptoms.


A meta-analysis found that oxidative ] was significantly increased in schizophrenia.<ref name = Goh2021>{{cite journal |vauthors=Goh XX, Tang PY, Tee SF |title= 8-Hydroxy-2'-Deoxyguanosine and Reactive Oxygen Species as Biomarkers of Oxidative Stress in Mental Illnesses: A Meta-Analysis |journal= Psychiatry Investig |volume=18 |issue=7 |pages=603–618 |date=July 2021 |pmid=34340273 |pmc=8328836 |doi=10.30773/pi.2020.0417 |type= Meta-analysis}}</ref>
The most commonly used criteria for diagnosing schizophrenia are from the ] ] (DSM) and the ] ] (ICD). The most recent versions are and .


===Environmental===
Below is an abbreviated version of the diagnostic criteria from the DSM-IV-TR; the full version is available .
{{Further|Prenatal nutrition|Prenatal stress|Neuroplastic effects of pollution}}


Environmental factors, each associated with a slight risk of developing schizophrenia in later life include ], infection, ], and malnutrition in the mother during prenatal development.<ref name=Stilo2019>{{cite journal |vauthors=Stilo SA, Murray RM |title=Non-Genetic Factors in Schizophrenia |journal=Current Psychiatry Reports |volume=21 |issue=10 |page=100 |date=14 September 2019 |pmid=31522306 |doi=10.1007/s11920-019-1091-3 |pmc=6745031 }}</ref> A risk is associated with maternal obesity, in increasing ], and dysregulating the dopamine and serotonin pathways.<ref>{{cite journal |vauthors=Cirulli F, Musillo C, Berry A |s2cid=211029692 |title=Maternal Obesity as a Risk Factor for Brain Development and Mental Health in the Offspring |journal=Neuroscience|date= 5 February 2020 |volume=447 |pages=122–135 |pmid=32032668|doi= 10.1016/j.neuroscience.2020.01.023|hdl=11573/1387747 |hdl-access=free }}</ref> Both maternal stress and infection have been demonstrated to alter fetal ] through an increase of pro-inflammatory ]s.<ref name=Upthegrove2020>{{cite journal |vauthors=Upthegrove R, Khandaker GM |title=Cytokines, Oxidative Stress and Cellular Markers of Inflammation in Schizophrenia |journal=Current Topics in Behavioral Neurosciences |volume=44 |pages=49–66 |date=2020 |pmid=31115797 |doi= 10.1007/7854_2018_88|isbn=978-3-030-39140-9 |s2cid=162169817 |url= http://pure-oai.bham.ac.uk/ws/files/74984176/Upthegrove_Khandaker_Cytokines_oxidative_stress_and_cellular_markers_of_inflammation_in_schizophrenia_Current_Topics_in_Behavioral_Neurosciences_2019.pdf }}</ref> There is a slighter risk associated with being born in the winter or spring possibly due to ]<ref name=Chiang2016>{{cite journal |vauthors=Chiang M, Natarajan R, Fan X |s2cid= 206926835 |title=Vitamin D in schizophrenia: a clinical review |journal= Evidence-Based Mental Health |volume=19 |issue=1 |pages=6–9 |date= February 2016 |pmid=26767392 |doi=10.1136/eb-2015-102117 |pmc=10699337 }}</ref> or a prenatal ].<ref name=BMJ07/> Other infections during pregnancy or around the time of birth that have been linked to an increased risk include infections by '']'' and '']''.<ref>{{cite journal | vauthors = Arias I, Sorlozano A, Villegas E, de Dios Luna J, McKenney K, Cervilla J, Gutierrez B, Gutierrez J | title = Infectious agents associated with schizophrenia: a meta-analysis | journal = Schizophrenia Research | volume = 136 | issue = 1–3 | pages = 128–136 | date = April 2012 | pmid = 22104141 | doi = 10.1016/j.schres.2011.10.026 | hdl-access = free | s2cid = 2687441 | hdl = 10481/90076 }}</ref> The increased risk is about five to eight percent.<ref name=yolken>{{cite journal | vauthors = Yolken R | title = Viruses and schizophrenia: a focus on herpes simplex virus | journal = Herpes | volume = 11 | issue = Suppl 2 | pages = 83A–88A | date = June 2004 | pmid = 15319094 }}</ref> Viral infections of the brain during childhood are also linked to a risk of schizophrenia during adulthood.<ref>{{cite journal | vauthors = Khandaker GM | title = Childhood infection and adult schizophrenia: a meta-analysis of population-based studies. | journal = Schizophr. Res. | volume = 139 | issue = 1–3 | pages = 161–168 |date = August 2012 | pmid = 22704639 | pmc = 3485564 | doi = 10.1016/j.schres.2012.05.023}}</ref> ] is also associated with an increased risk of broadly defined schizophrenia-related disorders, with an ] of 2.4.<ref>{{cite journal | title = Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis | journal = Schizophrenia Bulletin | volume = 50 | issue = 3 | pages = 489–495 | date = May 2024 | pmid = 38491934 | pmc = 11059805 | doi = 10.1093/schbul/sbad168 | vauthors = McGrath JJ, Lim CC, Saha S }}</ref>
To be diagnosed as having schizophrenia, a person must display:


] (ACEs), severe forms of which are classed as ], range from being bullied or abused, to the death of a parent.<ref name=Pearce2019>{{cite journal |vauthors=Pearce J, Murray C, Larkin W |title=Childhood adversity and trauma:experiences of professionals trained to routinely enquire about childhood adversity |journal=Heliyon |volume=5 |issue=7 |page=e01900 |date=July 2019 |pmid=31372522 |doi=10.1016/j.heliyon.2019.e01900|doi-access=free |pmc=6658729 |bibcode=2019Heliy...501900P }}</ref> Many adverse childhood experiences can cause ] and increase the risk of psychosis.<ref name=Pearce2019/><ref>{{cite journal | vauthors = Dvir Y, Denietolis B, Frazier JA | title = Childhood trauma and psychosis | journal = Child and Adolescent Psychiatric Clinics of North America | volume = 22 | issue = 4 | pages = 629–641 | date = October 2013 | pmid = 24012077 | doi = 10.1016/j.chc.2013.04.006 | s2cid = 40053289 }}</ref><ref>{{cite journal | vauthors = Misiak B, Krefft M, Bielawski T, Moustafa AA, Sąsiadek MM, Frydecka D | s2cid = 21614845 | title = Toward a unified theory of childhood trauma and psychosis: A comprehensive review of epidemiological, clinical, neuropsychological and biological findings | journal = Neuroscience and Biobehavioral Reviews | volume = 75 | pages = 393–406 | date = April 2017 | pmid = 28216171 | doi = 10.1016/j.neubiorev.2017.02.015 }}</ref> Chronic trauma, including ACEs, can promote lasting inflammatory dysregulation throughout the nervous system.<ref name=Nettis2020>{{cite journal | vauthors = Nettis MA, Pariante CM, Mondelli V | title = Early-Life Adversity, Systemic Inflammation and Comorbid Physical and Psychiatric Illnesses of Adult Life | journal = Current Topics in Behavioral Neurosciences | volume = 44 | pages = 207–225 | date = 2020 | pmid = 30895531 | doi = 10.1007/7854_2019_89 | isbn = 978-3-030-39140-9 | s2cid = 84842249 | url = https://kclpure.kcl.ac.uk/portal/en/publications/earlylife-adversity-systemic-inflammation-and-comorbid-physical-and-psychiatric-illnesses-of-adult-life(d2cdfc38-19e7-4918-80f1-5525e6ff45bf).html}}</ref> It is suggested that early stress may contribute to the development of schizophrenia through these alterations in the immune system.<ref name= Nettis2020/> Schizophrenia was the last diagnosis to benefit from the link made between ACEs and adult mental health outcomes.<ref>{{cite journal |vauthors=Guloksuz S, van Os J |title=The slow death of the concept of schizophrenia and the painful birth of the psychosis spectrum |journal=Psychological Medicine |volume=48 |issue=2 |pages=229–244 |date=January 2018 |pmid=28689498 |doi=10.1017/S0033291717001775|doi-access=free }}</ref>
*A) Characteristic symptoms: Two or more of the following, each present for a significant portion of time during a one-month period (or less, if successfully treated)
** ]s
** ]s
** disorganized speech (e.g., frequent derailment or incoherence; speaking in abstracts). See ].
** grossly disorganized behavior (e.g. dressing inappropriately, crying frequently) or ] behavior
** negative symptoms, i.e., ] (lack or decline in emotional response), ] (lack or decline in speech), or ] (lack or decline in motivation).


Living in an ] during childhood or as an adult has consistently been found to increase the risk of schizophrenia by a factor of two,<ref name= Lancet2009/><ref>{{cite journal |vauthors= Costa E, Silva JA, Steffen RE |title=Urban environment and psychiatric disorders: a review of the neuroscience and biology |journal=Metabolism: Clinical and Experimental |volume=100S |page=153940 |date=November 2019 |pmid=31610855|doi=10.1016/j.metabol.2019.07.004|s2cid=204704312 }}</ref> even after taking into account ], ], and size of ].<ref>{{cite journal | vauthors = van Os J | title = Does the urban environment cause psychosis? | journal = The British Journal of Psychiatry | volume = 184 | issue = 4 | pages = 287–8 | date = April 2004 | pmid = 15056569 | doi = 10.1192/bjp.184.4.287 | doi-access = free }}</ref> A possible link between the ] has been suggested to be the cause of the elevated risk of schizophrenia.<ref>{{cite journal |vauthors=Attademo L, Bernardini F, Garinella R, Compton MT |s2cid=25505446 |title= Environmental pollution and risk of psychotic disorders: A review of the science to date |journal=Schizophrenia Research |volume=181 |pages=55–59 |date=March 2017 |pmid=27720315 |doi=10.1016/j.schres.2016.10.003}}</ref> Other risk factors include ], immigration related to social adversity and racial discrimination, family dysfunction, unemployment, and poor housing conditions.<ref name=BMJ07/><ref>{{cite journal | vauthors = Selten JP, Cantor-Graae E, Kahn RS | s2cid = 21391349 | title = Migration and schizophrenia | journal = Current Opinion in Psychiatry | volume = 20 | issue = 2 | pages = 111–115 | date = March 2007 | pmid = 17278906 | doi = 10.1097/YCO.0b013e328017f68e }}</ref> Having a ], or parents younger than 20 years are also associated with schizophrenia.<ref name= Lancet2016 /><ref>{{cite journal | vauthors = Sharma R, Agarwal A, Rohra VK, Assidi M, Abu-Elmagd M, Turki RF | title = Effects of increased paternal age on sperm quality, reproductive outcome and associated epigenetic risks to offspring | journal = Reproductive Biology and Endocrinology | volume = 13 | pages = 35 | date = April 2015 | pmid = 25928123 | pmc = 4455614 | doi = 10.1186/s12958-015-0028-x | doi-access = free }}</ref>
:Note: Only one Criterion A symptom is required if delusions are bizarre or hallucinations consist of hearing one voice participating in a running commentary of the patient's actions or of hearing two or more voices conversing with each other.


====Substance use====
*B) Social/occupational dysfunction: For a significant portion of the time since the onset of the disturbance, one or more major areas of functioning such as work, interpersonal relations, or self-care, are markedly below the level achieved prior to the onset.
{{Further|Risk factors of schizophrenia#Substance use|Substance-induced psychosis}}


About half of those with schizophrenia use ] including ], tobacco, and ] excessively.<ref name=Gregg2007/><ref>{{cite journal | vauthors = Sagud M, Mihaljević-Peles A, Mück-Seler D, Pivac N, Vuksan-Cusa B, Brataljenović T, Jakovljević M | title = Smoking and schizophrenia | journal = Psychiatria Danubina | volume = 21 | issue = 3 | pages = 371–375 | date = September 2009 | pmid = 19794359 }}</ref> Use of ]s such as ] and ] can lead to a temporary ], which presents very similarly to schizophrenia. Rarely, alcohol use can also result in a similar ].<ref name= BMJ07/><ref name=alcohol>{{Cite journal |url= http://www.emedicine.com/med/topic3113.htm |title=Alcohol-Related Psychosis |access-date=27 September 2006 | vauthors = Larson M |date=30 March 2006 |journal=EMedicine |url-status=live |archive-url= https://web.archive.org/web/20081109011819/http://www.emedicine.com/MED/topic3113.htm |archive-date=9 November 2008}}</ref> Drugs may also be used as coping mechanisms by people who have schizophrenia, to deal with depression, ], boredom, and ].<ref name=Gregg2007>{{cite journal | vauthors = Gregg L, Barrowclough C, Haddock G | title = Reasons for increased substance use in psychosis | journal = Clinical Psychology Review | volume = 27 | issue = 4 | pages = 494–510 | date = May 2007 | pmid = 17240501 | doi = 10.1016/j.cpr.2006.09.004 }}</ref><ref name=Leweke08>{{cite journal | vauthors = Leweke FM, Koethe D | title = Cannabis and psychiatric disorders: it is not only addiction | journal = Addiction Biology | volume = 13 | issue = 2 | pages = 264–75 | date = June 2008 | pmid = 18482435 | doi = 10.1111/j.1369-1600.2008.00106.x | s2cid = 205400285 }}</ref> The use of cannabis and tobacco are not associated with the development of cognitive deficits, and sometimes a reverse relationship is found where their use improves these symptoms.<ref name=Vidailhet2013>{{cite journal | vauthors = Vidailhet P | title = . | journal = L'Encéphale | date = September 2013 | volume = 39 | issue = Suppl 2 | language= fr| pages = S83-92 | doi = 10.1016/S0013-7006(13)70101-5 | pmid=24084427}}</ref> However, ]s are associated with an increased risk of suicide, and a poor response to treatment.<ref name= Khokhar2018>{{cite book |vauthors=Khokhar JY, Henricks AM, Sullivan ED, Green AI |title=Apprentices to Genius: A tribute to Solomon H. Snyder |chapter=Unique Effects of Clozapine: A Pharmacological Perspective |series=Advances in Pharmacology |volume=82 |pages=137–162 |date=2018 |pmid=29413518|doi=10.1016/bs.apha.2017.09.009|pmc=7197512 |isbn=978-0128140871 }}</ref><ref>{{cite journal |vauthors=Bighelli I, Rodolico A, García-Mieres H, et al |title=Psychosocial and psychological interventions for relapse prevention in schizophrenia: a systematic review and network meta-analysis |journal=Lancet Psychiatry |volume=8 |issue=11 |pages=969–980 |date=November 2021 |pmid=34653393 |doi=10.1016/S2215-0366(21)00243-1 |s2cid=239003358 |doi-access=free |url=https://boris.unibe.ch/160225/8/Bighelli_LancetPsychiatry_2021.pdf }}</ref>
*C) Duration: Continuous signs of the disturbance persist for at least six months. This six-month period must include at least one month of symptoms (or less, if successfully treated) that meet Criterion A.


] may be a contributory factor in the development of schizophrenia, potentially increasing the risk of the disease in those who are already at risk.<ref name= Patel2020>{{cite journal |vauthors=Patel S, Khan S, M S, Hamid P |title=The Association Between Cannabis Use and Schizophrenia: Causative or Curative? A Systematic Review |journal= ] |volume=12 |issue=7 |pages=e9309 |date=July 2020 |pmid=32839678 |pmc=7442038 |doi=10.7759/cureus.9309 |doi-access=free |url=}}</ref><ref name= Hasan2020>{{cite journal |vauthors=Hasan A, von Keller R, Friemel CM, Hall W, Schneider M, Koethe D, Leweke FM, Strube W, Hoch E |title=Cannabis use and psychosis: a review of reviews |journal=Eur Arch Psychiatry Clin Neurosci |volume=270 |issue=4 |pages= 403–412 |date=June 2020 |pmid=31563981 |doi=10.1007/s00406-019-01068-z |s2cid=203567900 |url=}}</ref><ref>{{cite web |title=Causes — Schizophrenia | url= https://www.nhs.uk/mental-health/conditions/schizophrenia/causes/ |publisher= UK ] |date=11 November 2019 |access-date= 8 December 2021}}</ref> The increased risk may require the presence of certain genes within an individual.<ref name= Parakh2013>{{cite journal | vauthors = Parakh P, Basu D | title = Cannabis and psychosis: have we found the missing links? | journal = ] | volume = 6 | issue = 4 | pages = 281–287 | date = August 2013 | pmid = 23810133 | doi = 10.1016/j.ajp.2013.03.012 | type = Review | quote = Cannabis acts as a component cause of psychosis, that is, it increases the risk of psychosis in people with certain genetic or environmental vulnerabilities, though by itself, it is neither a sufficient nor a necessary cause of psychosis. }}</ref> Its use is associated with doubling the rate.<ref>{{cite journal | vauthors = Ortiz-Medina MB, Perea M, Torales J, Ventriglio A, Vitrani G, Aguilar L, Roncero C | title = Cannabis consumption and psychosis or schizophrenia development | journal = The International Journal of Social Psychiatry | volume = 64 | issue = 7 | pages = 690–704 | date = November 2018 | pmid = 30442059 | doi = 10.1177/0020764018801690 | s2cid = 53563635 }}</ref>
Additional criteria (D, E and F) are also given that exclude a diagnosis of schizophrenia if symptoms of ] or ] are present. Additionally a diagnosis of schizophrenia is excluded if the symptoms are the direct result of a substance (e.g., abuse of a drug, medication) or a general medical condition.


===Subtypes=== ==Causes==
{{Main|Causes of schizophrenia}}{{See also|Aberrant salience}}
Historically, schizophrenia in the ] was classified into simple, ], ], and ]. The DSM now contains five sub-classifications of schizophrenia, the ICD-10 identifies 7:
The causes of schizophrenia are still unknown. Several models have been put forward to explain the link between altered brain function and schizophrenia.<ref name=Lancet2009/> The prevailing model of schizophrenia is that of a neurodevelopmental disorder, and the underlying changes that occur before symptoms become evident are seen as arising from the ].<ref>{{cite journal |vauthors=Hayes D, Kyriakopoulos M |title=Dilemmas in the treatment of early-onset first-episode psychosis |journal=Therapeutic Advances in Psychopharmacology |volume=8 |issue=8 |pages=231–239 |date=August 2018 |pmid=30065814 |doi=10.1177/2045125318765725|pmc=6058451 |doi-access= free }}</ref> Extensive studies support this model.<ref name=George2017/> Maternal infections, malnutrition and ] and ] are known risk factors for the development of schizophrenia, which usually emerges between the ages of 18 and 25, a period that overlaps with certain stages of neurodevelopment.<ref>{{cite journal |vauthors=Cannon TD |title=How Schizophrenia Develops: Cognitive and Brain Mechanisms Underlying Onset of Psychosis |journal=Trends Cogn Sci |volume=19 |issue=12 |pages=744–756 |date= December 2015 |pmid=26493362 |pmc=4673025 |doi=10.1016/j.tics.2015.09.009 }}</ref> Gene-environment interactions lead to deficits in the ]ry that affect sensory and cognitive functions.<ref name=George2017/>


The common dopamine and glutamate models proposed are not mutually exclusive; each is seen to have a role in the neurobiology of schizophrenia.<ref>{{cite journal |vauthors=Correll CU, Schooler NR |title=Negative Symptoms in Schizophrenia: A Review and Clinical Guide for Recognition, Assessment, and Treatment |journal= Neuropsychiatric Disease and Treatment |volume=16 |pages=519–534 |date=2020 |pmid=32110026 |doi=10.2147/NDT.S225643 |pmc=7041437 |doi-access=free }}</ref> The most common model put forward was the ], which attributes psychosis to the mind's faulty interpretation of the misfiring of ].<ref>{{cite journal | vauthors = Howes OD | title = The Role of Genes, Stress, and Dopamine in the Development of Schizophrenia | journal = Biological Psychiatry | date = 1 January 2017 | volume = 81 | issue = 1 | pages = 9–20 | doi = 10.1016/j.biopsych.2016.07.014 | pmid = 27720198| pmc = 5675052 }}</ref> This has been directly related to the symptoms of delusions and hallucinations.<ref>{{cite journal|vauthors=Broyd A, Balzan RP, Woodward TS, Allen P|date=June 2017|title=Dopamine, cognitive biases and assessment of certainty: A neurocognitive model of delusions| url= https://kclpure.kcl.ac.uk/portal/en/publications/dopamine-cognitive-biases-and-assessment-of-certainty-a-neurocognitive-model-of-delusions(138513dd-3a44-4deb-bac1-be45767ef51b).html|journal=Clinical Psychology Review|volume=54|pages=96–106|doi= 10.1016/j.cpr.2017.04.006 |pmid= 28448827|s2cid=3729566 }}</ref><ref name=Lancet2014>{{cite journal | vauthors = Howes OD, Murray RM | title = Schizophrenia: an integrated sociodevelopmental-cognitive model | journal = Lancet | volume = 383 | issue = 9929 | pages = 1677–1687 | date = May 2014 | pmid = 24315522 | pmc = 4127444 | doi = 10.1016/S0140-6736(13)62036-X }}</ref><ref>{{cite journal | vauthors = Grace AA | title = Dysregulation of the dopamine system in the pathophysiology of schizophrenia and depression | journal = Nature Reviews. Neuroscience | volume = 17 | issue = 8 | pages = 524–532 | date = August 2016 | pmid = 27256556 | pmc = 5166560 | doi = 10.1038/nrn.2016.57 }}</ref> Abnormal dopamine signaling has been implicated in schizophrenia based on the usefulness of medications that affect the dopamine receptor and the observation that dopamine levels are increased during acute psychosis.<ref>{{cite journal | vauthors = Fusar-Poli P, Meyer-Lindenberg A | title = Striatal presynaptic dopamine in schizophrenia, part II: meta-analysis of -DOPA PET studies | journal = Schizophrenia Bulletin | volume = 39 | issue = 1 | pages = 33–42 | date = January 2013 | pmid = 22282454 | pmc = 3523905 | doi = 10.1093/schbul/sbr180 }}</ref><ref>{{cite journal | vauthors = Howes OD, Kambeitz J, Kim E, Stahl D, Slifstein M, Abi-Dargham A, Kapur S | title = The nature of dopamine dysfunction in schizophrenia and what this means for treatment | journal = Archives of General Psychiatry | volume = 69 | issue = 8 | pages = 776–786 | date = August 2012 | pmid = 22474070 | pmc = 3730746 | doi = 10.1001/archgenpsychiatry.2012.169 }}</ref> A decrease in ] in the ] may also be responsible for deficits in ].<ref>{{cite journal | vauthors = Arnsten AF, Girgis RR, Gray DL, Mailman RB | title = Novel Dopamine Therapeutics for Cognitive Deficits in Schizophrenia | journal = Biological Psychiatry | volume = 81 | issue = 1 | pages = 67–77 | date = January 2017 | pmid = 26946382 | pmc = 4949134 | doi = 10.1016/j.biopsych.2015.12.028 }}</ref><ref>{{cite journal | vauthors = Maia TV, Frank MJ | title = An Integrative Perspective on the Role of Dopamine in Schizophrenia | journal = Biological Psychiatry | volume = 81 | issue = 1 | pages = 52–66 | date = January 2017 | pmid = 27452791 | pmc = 5486232 | doi = 10.1016/j.biopsych.2016.05.021 }}</ref>
* (295.2/F20.2) '''catatonic type''' (where marked absences or peculiarities of movement are present),
* (295.1/F20.1) ''']''' (where thought disorder and flat affect are present together),
* (295.3/F20.0) '''paranoid type''' (where delusions and hallucinations are present but thought disorder, disorganized behavior, and affective flattening is absent),
* (295.6/F20.5) '''residual type''' (where positive symptoms are present at a low intensity only) and
* (295.9/F20.3) '''undifferentiated type''' (psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types has not been met).


The ] links alterations between ] and the ]s that affect ].<ref name=Pratt2017/> Studies have shown that a reduced expression of a ] – ], and glutamate blocking drugs such as ] and ] can mimic the symptoms and cognitive problems associated with schizophrenia.<ref name=Pratt2017>{{cite journal | vauthors = Pratt J, Dawson N, Morris BJ, Grent-'t-Jong T, Roux F, Uhlhaas PJ | title = Thalamo-cortical communication, glutamatergic neurotransmission and neural oscillations: A unique window into the origins of ScZ? | journal = Schizophrenia Research | volume = 180 | pages = 4–12 | date = February 2017 | pmid = 27317361 | doi = 10.1016/j.schres.2016.05.013 | s2cid = 205075178 | url = https://eprints.gla.ac.uk/132874/1/132874.pdf }}</ref><ref>{{cite journal | vauthors = Catts VS, Lai YL, Weickert CS, Weickert TW, Catts SV | title = A quantitative review of the post-mortem evidence for decreased cortical N-methyl-D-aspartate receptor expression levels in schizophrenia: How can we link molecular abnormalities to mismatch negativity deficits? | journal = Biological Psychology | volume = 116 | pages = 57–67 | date = April 2016 | pmid = 26549579 | doi = 10.1016/j.biopsycho.2015.10.013 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Michie PT, Malmierca MS, Harms L, Todd J | s2cid = 41179430 | title = The neurobiology of MMN and implications for schizophrenia | journal = Biological Psychology | volume = 116 | pages = 90–97 | date = April 2016 | pmid = 26826620 | doi = 10.1016/j.biopsycho.2016.01.011 }}</ref> Post-mortem studies consistently find that a subset of these neurons fail to express ] (]),<ref name = Marin2012>{{cite journal | vauthors = Marín O | s2cid = 205507186 | title = Interneuron dysfunction in psychiatric disorders | journal = Nature Reviews. Neuroscience | volume = 13 | issue = 2 | pages = 107–120 | date = January 2012 | pmid = 22251963 | doi = 10.1038/nrn3155 }}</ref> in addition to abnormalities in ]. The subsets of interneurons that are abnormal in schizophrenia are responsible for the synchronizing of neural ensembles needed during working memory tasks. These give the neural oscillations produced as ]s that have a frequency of between 30 and 80 ]. Both working memory tasks and gamma waves are impaired in schizophrenia, which may reflect abnormal interneuron functionality.<ref name = Marin2012 /><ref>{{cite journal | vauthors = Lewis DA, Hashimoto T, Volk DW | s2cid = 3335493 | title = Cortical inhibitory neurons and schizophrenia | journal = Nature Reviews. Neuroscience | volume = 6 | issue = 4 | pages = 312–324 | date = April 2005 | pmid = 15803162 | doi = 10.1038/nrn1648 }}</ref><ref>{{cite journal | vauthors = Senkowski D, Gallinat J | s2cid = 206104940 | title = Dysfunctional prefrontal gamma-band oscillations reflect working memory and other cognitive deficits in schizophrenia | journal = Biological Psychiatry | volume = 77 | issue = 12 | pages = 1010–1019 | date = June 2015 | pmid = 25847179 | doi = 10.1016/j.biopsych.2015.02.034 |quote=Several studies that investigated perceptual processes found impaired GBR in ScZ patients over sensory areas, such as the auditory and visual cortex. Moreover, studies examining steady-state auditory-evoked potentials showed deficits in the gen- eration of oscillations in the gamma band.}}</ref><ref>{{cite journal | vauthors = Reilly TJ, Nottage JF, Studerus E, Rutigliano G, Micheli AI, Fusar-Poli P, McGuire P | title = Gamma band oscillations in the early phase of psychosis: A systematic review | journal = Neuroscience and Biobehavioral Reviews | volume = 90 | pages = 381–399 | date = July 2018 | pmid = 29656029 | doi = 10.1016/j.neubiorev.2018.04.006 | quote = Decreased gamma power in response to a task was a relatively consistent finding, with 5 out of 6 studies reported reduced evoked or induced power. | s2cid = 4891072 | url = https://kclpure.kcl.ac.uk/portal/en/publications/e2f500b7-f358-433d-9f9c-7f6b9c52bb2f }}</ref> An important process that may be disrupted in neurodevelopment is astrogenesis – the formation of ]s. Astrocytes are crucial in contributing to the formation and maintenance of neural circuits and it is believed that disruption in this role can result in a number of neurodevelopmental disorders including schizophrenia.<ref name=Sloan2014>{{cite journal |vauthors=Sloan SA, Barres BA |title=Mechanisms of astrocyte development and their contributions to neurodevelopmental disorders |journal=Curr Opin Neurobiol |volume=27 |pages=75–81 |date=August 2014 |pmid=24694749 |pmc=4433289 |doi=10.1016/j.conb.2014.03.005 }}</ref> Evidence suggests that reduced numbers of astrocytes in deeper cortical layers are assocociated with a diminished expression of ], a ] in astrocytes; supporting the glutamate hypothesis.<ref name=Sloan2014/>
''NB:'' Brackets indicate codes for ] and ] diagnostic manuals, respectively. Some older classifications still use "Hebephrenic schizophrenia" instead of "Disorganized schizophrenia".


Deficits in ]s, such as planning, inhibition, and working memory, are pervasive in schizophrenia. Although these functions are separable, their dysfunction in schizophrenia may reflect an underlying deficit in the ability to represent goal related information in working memory, and to use this to direct cognition and behavior.<ref>{{cite journal | vauthors = Lesh TA, Niendam TA, Minzenberg MJ, Carter CS | title = Cognitive control deficits in schizophrenia: mechanisms and meaning |journal=Neuropsychopharmacology | volume = 36 | issue = 1 | pages = 316–338 | date = January 2011 | pmid = 20844478 |pmc = 3052853 |doi =10.1038/npp.2010.156 }}</ref><ref>{{cite journal | vauthors = Barch DM, Ceaser A | title = Cognition in schizophrenia: core psychological and neural mechanisms | journal = Trends in Cognitive Sciences | volume = 16 | issue = 1 | pages = 27–34 | date = January 2012 | pmid = 22169777 | pmc = 3860986 | doi = 10.1016/j.tics.2011.11.015 }}</ref> These impairments have been linked to a number of neuroimaging and neuropathological abnormalities. For example, functional neuroimaging studies report evidence of reduced neural processing efficiency, whereby the dorsolateral prefrontal cortex is activated to a greater degree to achieve a certain level of performance relative to controls on working memory tasks. These abnormalities may be linked to the consistent post-mortem finding of reduced ], evidenced by increased ] density and reduced ] density. These cellular and functional abnormalities may also be reflected in structural neuroimaging studies that find reduced ] volume in association with deficits in working memory tasks.<ref>{{cite journal | vauthors = Eisenberg DP, Berman KF | title = Executive function, neural circuitry, and genetic mechanisms in schizophrenia | journal = Neuropsychopharmacology | volume = 35 |issue = 1 | pages = 258–277 | date = January 2010 | pmid = 19693005 | pmc = 2794926 | doi = 10.1038/npp.2009.111}}</ref>
===Deficit Syndrome===
Currently, there is debate in the field about a new subtype known as the deficit syndrome. It is not currently included in the DSM-IV-TR, however it has been receiving a great deal of attention in the last 20 years. This subtype is more expansive than the other subtypes as a person can be diagnosed with both paranoid schizophrenia and the deficit syndrome. It is characterized by primary negative symptoms (which means that they cannot be caused by such things as the side-effects of medication or depression). People with the deficit syndrome tend to have extremely flat affect (do not appear to be very emotional), do not have good eye contact, do not enjoy normally pleasurable activities (see ]), and seem to be uninterested in social interaction. (There is, however, conflict in the research on this last point. While people who have been diagnosed with the deficit syndrome report being uninterested in social interaction, in the laboratory, they often report normal reactions to the situations.) Patients who have been diagnosed with the deficit syndrome tend to have a worse prognosis as these symptoms tend to be resistant to medication. This fact has brought much needed attention to negative symptoms (which have traditionally not been viewed as important as the positive symptoms).


Positive symptoms have been linked to cortical thinning in the ].<ref>{{cite journal | vauthors = Walton E, Hibar DP, van Erp TG, Potkin SG, Roiz-Santiañez R, Crespo-Facorro B, Suarez-Pinilla P, Van Haren NE, de Zwarte SM, Kahn RS, Cahn W, Doan NT, Jørgensen KN, Gurholt TP, Agartz I, Andreassen OA, Westlye LT, Melle I, Berg AO, Mørch-Johnsen L, Faerden A, Flyckt L, Fatouros-Bergman H, Jönsson EG, Hashimoto R, Yamamori H, Fukunaga M, Preda A, De Rossi P, Piras F, Banaj N, Ciullo V, Spalletta G, Gur RE, Gur RC, Wolf DH, Satterthwaite TD, Beard LM, Sommer IE, Koops S, Gruber O, Richter A, Krämer B, Kelly S, Donohoe G, McDonald C, Cannon DM, Corvin A, Gill M, Di Giorgio A, Bertolino A, Lawrie S, Nickson T, Whalley HC, Neilson E, Calhoun VD, Thompson PM, Turner JA, Ehrlich S | title = Positive symptoms associate with cortical thinning in the superior temporal gyrus via the ENIGMA Schizophrenia consortium | journal = Acta Psychiatrica Scandinavica | volume = 135 | issue = 5 | pages = 439–447 | date = May 2017 | pmid = 28369804 | pmc = 5399182 | doi = 10.1111/acps.12718 }}</ref> The severity of negative symptoms has been linked to reduced thickness in the left medial ].<ref>{{cite journal | vauthors = Walton E, Hibar DP, van Erp TG, Potkin SG, Roiz-Santiañez R, Crespo-Facorro B, Suarez-Pinilla P, van Haren NE, de Zwarte SM, Kahn RS, Cahn W, Doan NT, Jørgensen KN, Gurholt TP, Agartz I, Andreassen OA, Westlye LT, Melle I, Berg AO, Morch-Johnsen L, Færden A, Flyckt L, Fatouros-Bergman H, Jönsson EG, Hashimoto R, Yamamori H, Fukunaga M, Jahanshad N, De Rossi P, Piras F, Banaj N, Spalletta G, Gur RE, Gur RC, Wolf DH, Satterthwaite TD, Beard LM, Sommer IE, Koops S, Gruber O, Richter A, Krämer B, Kelly S, Donohoe G, McDonald C, Cannon DM, Corvin A, Gill M, Di Giorgio A, Bertolino A, Lawrie S, Nickson T, Whalley HC, Neilson E, Calhoun VD, Thompson PM, Turner JA, Ehrlich S | title = Prefrontal cortical thinning links to negative symptoms in schizophrenia via the ENIGMA consortium | journal = Psychological Medicine | volume = 48 | issue = 1 | pages = 82–94 | date = January 2018 | pmid = 28545597 | pmc = 5826665 | doi = 10.1017/S0033291717001283 | collaboration = Karolinska Schizophrenia Project Consortium (KaSP) }}</ref> Anhedonia, traditionally defined as a reduced capacity to experience pleasure, is frequently reported in schizophrenia. However, a large body of evidence suggests that ] are intact in schizophrenia,<ref>{{cite journal | vauthors = Cohen AS, Minor KS | title = Emotional experience in patients with schizophrenia revisited: meta-analysis of laboratory studies | journal = Schizophrenia Bulletin | volume = 36 | issue = 1 | pages = 143–150 | date = January 2010 | pmid = 18562345 | pmc = 2800132 | doi = 10.1093/schbul/sbn061 }}</ref> and that what is reported to be anhedonia is a reflection of dysfunction in other processes related to reward.<ref>{{cite journal | vauthors = Strauss GP, Gold JM | title = A new perspective on anhedonia in schizophrenia | journal = The American Journal of Psychiatry | volume = 169 | issue = 4 | pages = 364–373 | date = April 2012 | pmid = 22407079 | pmc = 3732829 | doi = 10.1176/appi.ajp.2011.11030447 }}</ref> Overall, a failure of reward prediction is thought to lead to impairment in the generation of cognition and behavior required to obtain rewards, despite normal hedonic responses.<ref>{{cite book | vauthors = Young J, Anticevic A, Barch D | veditors = Charney D, Buxbaum J, Sklar P, Nestler E |title=Charney & Nestler's Neurobiology of Mental Illness |date=2018 |publisher=Oxford University Press. |location=New York |isbn=9780190681425 |pages=215, 217 |edition=5th |chapter=Cognitive and Motivational Neuroscience of Psychotic Disorders |quote=Several recent reviews (e.g., Cohen and Minor, 2010) have found that individuals with schizophrenia show relatively intact self-reported emotional responses to affect-eliciting stimuli as well as other indicators of intact response(215)...Taken together, the literature increasingly suggests that there may be a deficit in putatively DA-mediated reward learning and/ or reward prediction functions in schizophrenia. Such findings suggest that impairment in striatal reward prediction mechanisms may influence "wanting" in schizophrenia in a way that reduces the ability of individuals with schizophrenia to use anticipated rewards to drive motivated behavior.(217)}}</ref>
===Presentation===
Symptoms may also be described as 'positive symptoms' (those additional to normal experience and behavior) and 'negative symptoms' (the lack or decline in normal experience or behavior). 'Positive symptoms' describe ] and typically include ], ] and ]. 'Negative symptoms' describe inappropriate or nonpresent emotion, ], and lack of motivation. In three-factor models of schizophrenia, a third symptom grouping, the so-called 'disorganization syndrome', is also given. This considers thought disorder and related disorganized behavior to be in a separate symptom cluster from delusions and hallucinations.


Another theory links abnormal ] to the development of ] which is significantly more common in those with schizophrenia.<ref name=Wilberg2019>{{cite journal | vauthors = Wiberg A, Ng M, Al Omran Y, Alfaro-Almagro F, McCarthy P, Marchini J, Bennett DL, Smith S, Douaud G, Furniss D | title = Handedness, language areas and neuropsychiatric diseases: insights from brain imaging and genetics | journal = Brain | volume = 142 | issue = 10 | pages = 2938–2947 | date = October 2019 | pmid = 31504236 | pmc = 6763735 | doi = 10.1093/brain/awz257 }}</ref> This abnormal development of hemispheric asymmetry is noted in schizophrenia.<ref>{{cite book |vauthors=Tzourio-Mazoyer N, Kennedy H, Van Essen DC, Christen Y |title=Micro-, Meso- and Macro-Connectomics of the Brain |chapter=Intra- and Inter-hemispheric Connectivity Supporting Hemispheric Specialization |series=Research and Perspectives in Neurosciences |date=2016 |pages=129–146 |doi=10.1007/978-3-319-27777-6_9 |pmid=28590670|isbn=978-3-319-27776-9 |s2cid=147813648 }}</ref> Studies have concluded that the link is a true and verifiable effect that may reflect a genetic link between lateralization and schizophrenia.<ref name=Wilberg2019/><ref>{{cite journal | vauthors = Ocklenburg S, Güntürkün O, Hugdahl K, Hirnstein M | title = Laterality and mental disorders in the postgenomic age—A closer look at schizophrenia and language lateralization | journal = Neuroscience and Biobehavioral Reviews | volume = 59 | pages = 100–110 | date = December 2015 | pmid = 26598216 | doi = 10.1016/j.neubiorev.2015.08.019 | s2cid = 15983622 }}</ref>
Some symptoms, such as social isolation, may be caused by a number of factors. One possible factor is impairment in ], which is associated with schizophrenia, but isolation may also result from an individual reacting to psychotic symptoms (such as paranoia) or avoiding potentially stressful social situations which may exacerbate mental distress in some people.


] have been used to link abnormalities in cellular functioning to symptoms.<ref>{{cite journal | vauthors = Friston KJ, Stephan KE, Montague R, Dolan RJ | title = Computational psychiatry: the brain as a phantastic organ | journal = The Lancet. Psychiatry | volume = 1 | issue = 2 | pages = 148–158 | date = July 2014 | pmid = 26360579 | doi = 10.1016/S2215-0366(14)70275-5 | s2cid = 15504512 }}</ref><ref>{{cite journal | vauthors = Griffin JD, Fletcher PC | title = Predictive Processing, Source Monitoring, and Psychosis | journal = Annual Review of Clinical Psychology | volume = 13 | pages = 265–289 | date = May 2017 | pmid = 28375719 | pmc = 5424073 | doi = 10.1146/annurev-clinpsy-032816-045145}}</ref> Both hallucinations and delusions have been suggested to reflect improper encoding of ], thereby causing expectation to excessively influence sensory perception and the formation of beliefs. In approved models of ] that mediate ], reduced NMDA receptor activation, could in theory result in the positive symptoms of delusions and hallucinations.<ref>{{cite journal | vauthors = Fletcher PC, Frith CD | s2cid = 6219485 | title = Perceiving is believing: a Bayesian approach to explaining the positive symptoms of schizophrenia | journal = Nature Reviews. Neuroscience | volume = 10 | issue = 1 | pages = 48–58 | date = January 2009 | pmid = 19050712 | doi = 10.1038/nrn2536 | url = https://pure.au.dk/ws/files/48560345/fletcher_frithNRN.pdf }}</ref><ref>{{cite journal | vauthors = Corlett PR, Taylor JR, Wang XJ, Fletcher PC, Krystal JH | title = Toward a neurobiology of delusions | journal = Progress in Neurobiology | volume = 92 | issue = 3 | pages = 345–369 | date = November 2010 | pmid = 20558235 | pmc = 3676875 | doi = 10.1016/j.pneurobio.2010.06.007 }}</ref><ref>{{cite journal | vauthors = Bastos AM, Usrey WM, Adams RA, Mangun GR, Fries P, Friston KJ | title = Canonical microcircuits for predictive coding | journal = Neuron | volume = 76 | issue = 4 | pages = 695–711 | date = November 2012 | pmid = 23177956 | pmc = 3777738 | doi = 10.1016/j.neuron.2012.10.038 }}</ref>
It is worth noting that many of the positive or psychotic symptoms may occur in a variety of disorders and not only in schizophrenia. The psychiatrist ] tried to list the particular forms of psychotic symptoms that he thought were particularly useful in distinguishing between schizophrenia and other disorders that could produce psychosis. These are called ''first rank symptoms'' or ''Schneiderian first rank symptoms'' and include delusions of being controlled by an external force, the belief that thoughts are being inserted into or withdrawn from your conscious mind, the belief that your thoughts are being broadcast to other people and hearing hallucinated voices which comment on your thoughts or actions, or may have a conversation with other hallucinated voices. As with other diagnostic methods, the reliability of 'first rank symptoms' has been questioned<ref name="fn_4"> Schizophrenia and Related Disorders: Experience with Current Diagnostic Systems. ''Psychopathology'', 35, 89&ndash;93.<br></ref>, although they remain in use as diagnostic criteria in many countries.


==Diagnosis==
===Diagnostic issues and controversies===
{{Main|Diagnosis of schizophrenia}}
It has been argued that the diagnostic approach to schizophrenia is flawed, as it relies on an assumption of a clear dividing line between what is considered to be ] (fulfilling the diagnostic criteria) and ] (not fulfilling the criteria). Recently it has been argued, notably by psychiatrist ] and psychologist ], that this makes little sense, as studies have shown that many people have psychotic experiences<ref name="fn_5"> Psychotic symptoms in non-clinical populations and the continuum of psychosis. ''Schizophrenia Research'', 54(1&ndash;2), 59&ndash;65.<br></ref> <ref name="fn_65"> The continuity of psychotic experiences in the general population. ''Clinical Psychology Review'', 21 (8),1125-41.<br></ref> and have delusion-like ideas<ref name="fn_67"> Measuring delusional ideation: the 21-item Peters et al. Delusions Inventory (PDI). ''Schizophrenia Bulletin'', 30, 1005-22.<br></ref> without becoming distressed, disabled or diagnosable by the categorical system (potentially because they interpret their experiences in more positive ways, or hold more pragmatic and commonly accepted beliefs).


===Criteria===
Of particular concern is that the decision as to whether a symptom is present is a subjective decision by the person making the diagnosis or relies on an incoherent definition (for example, see the entries on ]s and ] for a discussion of this issue). More recently, it has been argued that psychotic symptoms are not a good basis for making a diagnosis of schizophrenia as "psychosis is the 'fever' of mental illness &mdash; a serious but nonspecific indicator".<ref name="fn_6"> Toward reformulating the diagnosis of schizophrenia. ''American Journal of Psychiatry'', 157(7), 1041&ndash;1050.<br></ref>
Schizophrenia is diagnosed based on criteria in either the '']'' (DSM) published by the ] or the ] (ICD) published by the ] (WHO). These criteria use the self-reported experiences of the person and reported abnormalities in behavior, followed by a ]. The ] is an important part of the assessment.<ref>{{cite journal | vauthors = Soltan M, Girguis J | title = How to approach the mental state examination | url = https://www.bmj.com/content/357/sbmj.j1821 | journal = BMJ | volume = 357 | page = j1821 | access-date = 9 January 2020 | doi = 10.1136/sbmj.j1821 | pmid = 31055448 | date = 8 May 2017| s2cid = 145820368 }}</ref> An established tool for assessing the severity of positive and negative symptoms is the Positive and Negative Syndrome Scale (PANSS).<ref>{{cite journal | vauthors = Lindenmayer JP | title = Are Shorter Versions of the Positive and Negative Syndrome Scale (PANSS) Doable? A Critical Review. | journal = Innovations in Clinical Neuroscience | date = 1 December 2017 | volume = 14 | issue = 11–12 |pages=73–76 | pmid = 29410940| pmc = 5788254 }}</ref> This has been seen to have shortcomings relating to negative symptoms, and other scales – the ''Clinical Assessment Interview for Negative Symptoms'' (CAINS), and the ''Brief Negative Symptoms Scale'' (BNSS) have been introduced.<ref name=Marder2014/> The ], published in 2013, gives a ''Scale to Assess the Severity of Symptom Dimensions'' outlining eight dimensions of symptoms.<ref name=Biedermann2016/>


DSM-5 states that to be diagnosed with schizophrenia, two diagnostic criteria have to be met over the period of one month, with a significant impact on social or occupational functioning for at least six months. One of the symptoms needs to be either delusions, hallucinations, or disorganized speech. A second symptom could be one of the negative symptoms, or severely disorganized or ].<ref name=DSM5/> A different diagnosis of ] can be made before the six months needed for the diagnosis of schizophrenia.<ref name=DSM5/>
Perhaps because of these factors, studies examining the ] of schizophrenia have typically shown relatively low or inconsistent levels of diagnostic reliability. Most famously, ] 1972 study, published as '']'', demonstrated that the diagnosis of schizophrenia was (at least at the time) often subjective and unreliable. More recent studies have found agreement between any two psychiatrists when diagnosing schizophrenia tends to reach about 65% at best<ref name="fn_7"> Spurious precision: procedural validity of diagnostic assessment in psychotic disorders. ''American Journal of Psychiatry'', 152 (2), 220&ndash;3.<br></ref>. This, and the results of earlier studies of diagnostic reliability (which typically reported even lower levels of agreement) have led some critics to argue that the diagnosis of schizophrenia should be abandoned.<ref name="fn_8">Read, J. (2004) Does 'schizophrenia' exist? Reliability and validity. In J. Read, L.R. Mosher, R.P. Bentall (eds) ''Models of Madness: Psychological, Social and Biological Approaches to Schizophrenia''. ISBN 1-58391-906-6<br></ref>


In Australia, the guideline for diagnosis is for six months or more with symptoms severe enough to affect ordinary functioning.<ref>{{cite web |title=Diagnosis of schizophrenia |url=https://www.healthdirect.gov.au/diagnosis-of-schizophrenia |publisher= Australian Department of Health |access-date=28 January 2020 |date=10 January 2019}}</ref> In the UK diagnosis is based on having the symptoms for most of the time for one month, with symptoms that significantly affect the ability to work, study, or carry on ordinary daily living, and with other similar conditions ruled out.<ref>{{cite web |title=Schizophrenia – Diagnosis |url=https://www.nhs.uk/conditions/schizophrenia/diagnosis/ |publisher= UK ] |access-date=28 January 2020 |date=23 October 2017}}</ref>
In 2004 in Japan, the category of schizophrenia was abandoned and replaced with ].<ref name="Sato"> Renaming schizophrenia: a Japanese perspective. ''World Psychiatry'', 5(1), 53-5.</ref> In 2006, campaigners in the UK, under the banner of ], argued for a similar rejection of the diagnosis of schizophrenia and a different approach to the treatment and understanding of the symptoms currently associated with it.<ref name="schizophrenia_invalid">BBC News Online, (9 October 2006) </ref>


The ICD criteria are typically used in European countries; the DSM criteria are used predominantly in the United States and Canada, and are prevailing in research studies. In practice, agreement between the two systems is high.<ref>{{cite journal | vauthors = Jakobsen KD, Frederiksen JN, Hansen T, Jansson LB, Parnas J, Werge T | title = Reliability of clinical ICD-10 schizophrenia diagnoses | journal = Nordic Journal of Psychiatry | volume = 59 | issue = 3 | pages = 209–212 | year = 2005 | pmid = 16195122 | doi = 10.1080/08039480510027698 | s2cid = 24590483 }}</ref> The current proposal for the ] criteria for schizophrenia recommends adding self-disorder as a symptom.<ref name=Heinz2016/>
Alternatively, other proponents have argued for a new approach that would use the presence of specific ]s to make a diagnosis. These often accompany schizophrenia and take the form of a reduction or impairment in basic psychological functions such as ], ], ] and ]. It is these sorts of difficulties, rather than the psychotic symptoms (which can in many cases be controlled by ] medication), which seem to be the cause of most ] in schizophrenia. However, this argument is relatively new and it is unlikely that the method of diagnosing schizophrenia will change radically in the near future.


A major unresolved difference between the two diagnostic systems is that of the requirement in DSM of an impaired functional outcome. WHO for ICD argues that not all people with schizophrenia have functional deficits and so these are not specific for the diagnosis.<ref name=Biedermann2016/>
The diagnostic approach to schizophrenia has also been opposed by the proponents of the ] movement, who argue that classifying specific thoughts and behaviors as an illness allows ] of people that society finds undesirable but who have committed no crime. They argue that this is a way of ] classifying a social problem as a medical one to allow the forcible detention and treatment of people displaying these behaviors, which is something which can be done under ] in most ].


=== Neuroimaging techniques ===
An example of this can be seen in the ], where an additional sub-classification of ] was created. Particularly in the ] (Russian Soviet Federated Socialist Republic), this diagnosis was used for the purpose of silencing political dissidents or forcing them to recant their ideas by the use of forcible confinement and treatment. In 2000 similar concerns about the abuse of psychiatry to unjustly silence and detain practitioners of the ] movement by the Chinese government led the ] ''Committee on the Abuse of Psychiatry and Psychiatrists'' to pass a resolution to urge the ] to investigate the situation in ].
] has become a tool in understanding brain activity and connectivity differences in individuals with schizophrenia. Through resting-state fMRI, researchers have observed altered connectivity patterns within several key brain networks, such as the default mode network (DMN),<ref>{{Cite journal |last1=Whitfield-Gabrieli |first1=Susan |last2=Ford |first2=Judith M. |date=2012-04-27 |title=Default Mode Network Activity and Connectivity in Psychopathology |url=https://www.annualreviews.org/doi/10.1146/annurev-clinpsy-032511-143049 |journal=Annual Review of Clinical Psychology |language=en |volume=8 |issue=1 |pages=49–76 |doi=10.1146/annurev-clinpsy-032511-143049 |pmid=22224834 |issn=1548-5943}}</ref> salience network (SN),<ref>{{Cite journal |last=Menon |first=Vinod |date=October 2011 |title=Large-scale brain networks and psychopathology: a unifying triple network model |url=https://linkinghub.elsevier.com/retrieve/pii/S1364661311001719 |journal=Trends in Cognitive Sciences |language=en |volume=15 |issue=10 |pages=483–506 |doi=10.1016/j.tics.2011.08.003|pmid=21908230 }}</ref> and central executive network (CEN).<ref>{{Cite journal |last1=Baker |first1=Justin T. |last2=Holmes |first2=Avram J. |last3=Masters |first3=Grace A. |last4=Yeo |first4=B. T. Thomas |last5=Krienen |first5=Fenna |last6=Buckner |first6=Randy L. |last7=Öngür |first7=Dost |date=2014-02-01 |title=Disruption of Cortical Association Networks in Schizophrenia and Psychotic Bipolar Disorder |journal=JAMA Psychiatry |language=en |volume=71 |issue=2 |pages=109–118 |doi=10.1001/jamapsychiatry.2013.3469 |issn=2168-622X |pmc=4435541 |pmid=24306091}}</ref> Alterations may underlie cognitive and emotional symptoms in schizophrenia, such as disorganized thinking, impaired attention, and emotional dysregulation.


===Comorbidities===
Western psychiatric medicine tends to favor a definition of symptoms that depends on form rather than content (an innovation first argued for by psychiatrists ] and ]). Therefore, a subject should be able to believe anything, however unusual or socially unacceptable, without being diagnosed delusional, unless their belief is held in a particular way. In principle, this would stop people being forcibly detained or treated simply for what they believe. However, the distinction between form and content is not easy, or always possible, to make in practice (see ]). This had led to accusations by ], ] and mental health system survivor groups that psychiatric abuses exist in the West as well.
] showing overlapping ]s in genes associated with ] of ] (ASD), ], ] and schizophrenia:
{{legend|#007fff|Genes associated with epilepsy}}
{{legend|#007f7f|Genes associated with schizophrenia}}
{{legend|#d4aaff|Genes associated with autism spectrum disorder}}
{{legend|#ff0000|Genes associated with dystonia}}]]
Many people with schizophrenia may have one or more ], such as ], ], or substance use disorder. These are separate disorders that require treatment.<ref name=DSM5/> When comorbid with schizophrenia, substance use disorder and ] both increase the risk for violence.<ref name=Richard-Devantoy2009/> Comorbid substance use disorder also increases the risk of suicide.<ref name=Khokhar2018/>


]s often co-occur with schizophrenia, and may be an early sign of relapse.<ref name=Staedt2010/> Sleep disorders are linked with positive symptoms such as ] and can adversely affect ] and cognition.<ref name=Staedt2010>{{cite journal |vauthors=Staedt J, Hauser M, Gudlowski Y, Stoppe G |title=Sleep disorders in schizophrenia |journal=Fortschritte der Neurologie-Psychiatrie |volume=78 |issue=2 |pages=70–80 |date=February 2010 |pmid=20066610 |doi=10.1055/s-0028-1109967|s2cid=260137215 }}</ref> The consolidation of memories is disrupted in sleep disorders.<ref name=Pocivavsek2018/> They are associated with severity of illness, a poor prognosis, and poor quality of life.<ref name=Monti2013/><ref>{{cite journal |vauthors=Faulkner SM, Bee PE, Meyer N, Dijk DJ, Drake RJ |title=Light therapies to improve sleep in intrinsic circadian rhythm sleep disorders and neuro-psychiatric illness: A systematic review and meta-analysis |journal=Sleep Medicine Reviews |volume=46 |pages=108–123 |date=August 2019 |pmid=31108433|doi=10.1016/j.smrv.2019.04.012|doi-access=free }}</ref> Sleep onset and maintenance insomnia is a common symptom, regardless of whether treatment has been received or not.<ref name=Monti2013>{{cite journal | vauthors = Monti JM, BaHammam AS, Pandi-Perumal SR, Bromundt V, Spence DW, Cardinali DP, Brown GM | title = Sleep and circadian rhythm dysregulation in schizophrenia | journal = Progress in Neuro-Psychopharmacology & Biological Psychiatry | volume = 43 | pages = 209–216 | date = June 2013 | pmid = 23318689 | doi = 10.1016/j.pnpbp.2012.12.021 | hdl-access = free | s2cid = 19626589 | hdl = 11336/3858 }}</ref> Genetic variations have been found associated with these conditions involving the ], dopamine and ], and signal transduction.<ref>{{cite journal | vauthors = Assimakopoulos K, Karaivazoglou K, Skokou M, Kalogeropoulou M, Kolios P, Gourzis P, Patrinos GP, Tsermpini EE | title = Genetic Variations Associated with Sleep Disorders in Patients with Schizophrenia: A Systematic Review | journal = Medicines | volume = 5 | issue = 2 | page = 27 | date = March 2018 | pmid = 29587340 | pmc = 6023503 | doi = 10.3390/medicines5020027 | doi-access = free }}</ref>
==Causes==
===Genetic and environmental influences===
While the reliability of the schizophrenia diagnosis introduces difficulties in measuring the relative effect of genes and environment (for example, symptoms overlap to some extent with severe ] or major depression), evidence suggests that genetic vulnerability and environmental stressors can act in combination to result in diagnosis of schizophrenia<ref name="fn_12"> Genes for schizophrenia? Recent findings and their pathophysiological implications. '''', 361(9355), 417&ndash;9.<br></ref>.


Schizophrenia is also associated with a number of somatic comorbidities including ], ]s, and ]s. The association of these with schizophrenia may be partially due to medications (e.g. ] from antipsychotics), environmental factors (e.g. complications from an increased rate of cigarette smoking), or associated with the disorder itself (e.g. diabetes mellitus type 2 and some cardiovascular diseases are thought to be genetically linked). These somatic comorbidities contribute to reduced life expectancy among persons with the disorder.<ref>{{cite journal |vauthors=Dieset I, Andreassen O, Haukvik U|title=Somatic Comorbidity in Schizophrenia: Some Possible Biological Mechanisms Across the Life Span |journal= Schizophrenia Bulletin|volume=42 |issue=6 |date=2016 |pages=1316–1319 | pmid=27033328|doi=10.1093/schbul/sbw028 |pmc=5049521 |doi-access=free }}</ref>
The extent to which these factors influence the likelihood of being diagnosed with schizophrenia is debated widely, and currently, controversial. Schizophrenia is likely to be a diagnosis of complex inheritance (analogous to ] or ]). Thus, it is likely that several ] interact to generate risk for it<ref name="fn_75"> Schizophrenia: genes at last? ''Trends in Genetics'', 21(9), 518-25.<br></ref>. This, combined with disagreements over which research methods are best, or how data from genetic research should be interpreted, has led to differing estimates over genetic contribution.


====Genetic==== ===Differential diagnosis===
{{see also|Dual diagnosis|Comparison of bipolar disorder and schizophrenia}}
Substantial evidence suggests that the diagnosis of schizophrenia has a heritable component (some estimates are as high as 80%). Current research suggests that environmental factors play a significant role in the expression of any genetic disposition towards schizophrenia (i.e. if someone has the genes that increase risk, this will not automatically result in a diagnosis of schizophrenia later in life). A recent review of the genetic evidence has suggested a more than 28% chance of one identical twin obtaining the diagnosis if the other already has it<ref name="fn_9">], Bowler, A.E., Taylor, E.H. & Gottesman, I.I (1994) ''Schizophrenia and manic depressive disorder''. New York: Basic books. ISBN 0-465-07285-2<br></ref> (see ]), but such studies are not noted for pondering the likelihood of similarities of social class and/or other socio-psychological factors between the twins. The estimates of heritability of schizophrenia from twin studies varies a great deal, with some notable studies<ref name="fn_10"> Psychiatric hospitalization in twins. ''Acta Genet Med Gemellol (Roma)'', 33(2),321-32.<br></ref> <ref name="fn_11"> Schizophrenia in the NAS-NRC panel of 15,909 veteran twin pairs. ''Archives of General Psychiatry'', 1970 Nov; 23(5):469-77.<br></ref> showing rates as low as 11.0%&ndash;13.8% among monozygotic twins, and 1.8%&ndash;4.1% among dizygotic twins. However, ] and a vocal lobby of psychiatrists and scientists who are at present in the minority have taken to task the twin studies, and have argued that the genetic basis of schizophrenia is open to question.
To make a diagnosis of schizophrenia ].<ref>{{cite journal |vauthors=Schrimpf LA, Aggarwal A, Lauriello J |title=Psychosis |journal=Continuum (Minneap Minn) |volume=24 |issue=3 |pages=845–860 |date=June 2018 |pmid=29851881 |doi=10.1212/CON.0000000000000602|s2cid=243933980 }}</ref>{{Rp|page=858|quote=Psychosis as a primary mental health disorder is a diagnosis of exclusion. Many different manifestations of psychotic symptoms are directly related to an underlying medical or neurologic disorder. Delirium and dementia are the two most important disorders to rule out and can present in a very subtle fashion.}} Psychotic symptoms lasting less than a month may be diagnosed as ], or as schizophreniform disorder. Psychosis is noted in ''Other specified schizophrenia spectrum and other psychotic disorders'' as a DSM-5 category. ] is diagnosed if symptoms of ] are substantially present alongside psychotic symptoms. Psychosis that results from a general medical condition or substance is termed secondary psychosis.<ref name=DSM5/><!-- cites previous four sentences -->


Psychotic symptoms may be present in several other conditions, including ],<ref name=Ferri2010/> ],<ref name=Paris2018>{{cite journal | vauthors = Paris J | title = Differential Diagnosis of Borderline Personality Disorder | journal = The Psychiatric Clinics of North America | date = December 2018 | volume = 41 | issue = 4 | pages=575–582 | doi = 10.1016/j.psc.2018.07.001 | pmid = 30447725| s2cid = 53951650 }}</ref> ], ], and a number of ]s. Non-bizarre delusions are also present in ], and social withdrawal in ], ] and ]. Schizotypal personality disorder has symptoms that are similar but less severe than those of schizophrenia.<ref name=DSM5/> Schizophrenia occurs along with obsessive–compulsive disorder (OCD) considerably more often than could be explained by chance, although it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia.<ref>{{cite journal | vauthors = Bottas A |title=Comorbidity: Schizophrenia With Obsessive-Compulsive Disorder |journal=Psychiatric Times |volume=26 |issue=4 |date=15 April 2009 |url=http://www.psychiatrictimes.com/display/article/10168/1402540 |url-status=live |archive-url=https://web.archive.org/web/20130403064649/http://www.psychiatrictimes.com/display/article/10168/1402540 |archive-date=3 April 2013}}</ref> There can be considerable overlap with the symptoms of ].<ref>{{cite journal |vauthors=OConghaile A, DeLisi LE |title=Distinguishing schizophrenia from posttraumatic stress disorder with psychosis |journal=Curr Opin Psychiatry |volume=28 |issue=3 |pages=249–255 |date=May 2015 |pmid=25785709 |doi=10.1097/YCO.0000000000000158 |s2cid=12523516 }}</ref>
There is currently a great deal of effort being put into ] studies of schizophrenia, which attempt to identify specific genes which may increase risk. Because of this, the genes that are thought to be most involved can change as new evidence is gathered. A 2003 review of ] studies listed seven genes as likely to increase risk for a later diagnosis of the disorder.<ref name="fn_12" /> Two more recent reviews<ref name="fn_75" /> <ref name="fn_79"> Molecular genetic studies of schizophrenia. ''Eur J Hum Genet'', 14 (6), 669-80.<br></ref> have suggested that the evidence is currently strongest for two genes known as ] (DTNBP1) and ] (NRG1), with a number of other genes (such as ], RGS4, PPP3CC, ZDHHC8, DISC1, and AKT1) showing some early promising results that have not yet been fully replicated.


A more general medical and neurological examination may be needed to rule out medical illnesses which may rarely produce psychotic schizophrenia-like symptoms, such as ], ], ], ], ], ], and brain lesions. Stroke, ], ], ], and ]s such as ], ], ], and the ]s may also be associated with schizophrenia-like psychotic symptoms.<ref>{{cite book|title=Bradley's neurology in clinical practice|year=2012|publisher=Elsevier/Saunders|location=Philadelphia, PA|isbn=978-1-4377-0434-1| vauthors= Murray ED, Buttner N, Price BH | volume = 1 | edition=6th|pages=92–111| veditors = Bradley WG, Daroff RB, Fenichel GM, Jankovic J |chapter=Depression and Psychosis in Neurological Practice}}</ref> It may be necessary to rule out a ], which can be distinguished by visual hallucinations, acute onset and fluctuating ], and indicates an underlying medical illness. Investigations are not generally repeated for relapse unless there is a specific ''medical'' indication or possible ] from ].<ref>{{cite journal |vauthors=Leucht S, Bauer S, Siafis S, Hamza T, Wu H, Schneider-Thoma J, Salanti G, Davis JM |title=Examination of Dosing of Antipsychotic Drugs for Relapse Prevention in Patients With Stable Schizophrenia: A Meta-analysis |journal=JAMA Psychiatry |volume=78 |issue=11 |pages=1238–1248 |date=November 2021 |pmid=34406325 |pmc=8374744 |doi=10.1001/jamapsychiatry.2021.2130}}</ref> In children hallucinations must be separated from typical childhood fantasies.<ref name=DSM5/> It is difficult to distinguish childhood schizophrenia from autism.<ref name=DaFonseca2018/>
====Environmental====
Considerable evidence indicates that stressful life events cause or trigger schizophrenia.<ref name="fn_15">. Stressful life events preceding the acute onset of schizophrenia: a cross-national study from the World Health Organization. ''Culture, Medicine and Psychiatry'', 11 (2), 123&ndash;205<br></ref> Childhood experiences of abuse or trauma have also been implicated as risk factors for a diagnosis of schizophrenia later in life.<ref name="fn_16"> Childhood Abuse and Lifetime Psychopathology in a Community Sample. ''American Journal of Psychiatry'',158, 1878-83.<br></ref> <ref name="fn_17"> Histories of childhood maltreatment in schizophrenia: Relationships with premorbid functioning, symptomatology, and cognitive deficits. ''Schizophrenia Research''<br></ref> <ref name="fn_18"> Childhood abuse as a risk factor for psychotic experiences. ''Acta Psychiatrica Scandinavica'', 109, 38-45.<br></ref>


==Prevention==
Evidence is also consistent that negative attitudes towards individuals with (or with a risk of developing) schizophrenia can have a significant adverse impact. In particular, critical comments, hostility, authoritarian and intrusive or controlling attitudes (termed 'high expressed emotion' by researchers) from family members have been found to correlate with a higher risk of relapse in schizophrenia across cultures.<ref name="fn_70"> The predictive utility of expressed emotion in schizophrenia: an aggregate analysis. ''Psychological Medicine'', 24, 707-718.<br></ref> It is not clear whether such attitudes play a causal role in the onset of schizophrenia, although those diagnosed in this way may claim it to be the primary causal factor. The research has focused on family members but also appears to relate to professional staff in regular contact with clients.<ref name="fn_71"> Expressed emotion of professionals towards mental health patients. ''Epidemiologia e Psychiatria Sociale'', 12(4), 232-235. ()<br></ref> While initial work addressed those diagnosed as schizophrenic, these attitudes have also been found to play a significant role in other mental health problems.<ref name="fn_66"> A review of expressed emotion research in health care. ''Clinical Psychology Review'', 20, 633-66.<br></ref> This approach does not blame 'bad parenting' or staffing, but addresses the attitudes, behaviors and interactions of all parties. Some go as far as to criticise the whole approach of seeking to localise 'mental illness' within one individual - the patient - rather than his/her group and its functionality, citing a ] effect.
] of schizophrenia is difficult as there are no reliable markers for the later development of the disorder.<ref>{{cite journal | vauthors = Cannon TD, Cornblatt B, McGorry P | title = The empirical status of the ultra high-risk (prodromal) research paradigm | journal = Schizophrenia Bulletin | volume = 33 | issue = 3 | pages = 661–664 | date = May 2007 | pmid = 17470445 | pmc = 2526144 | doi = 10.1093/schbul/sbm031 }}</ref>


] diagnose and treat patients in the prodromal phase of the illness. There is some evidence that these programs reduce symptoms. Patients tend to prefer early treatment programs to ordinary treatment and are less likely to disengage from them. As of 2020, it is unclear whether the benefits of early treatment persist once the treatment is terminated.<ref>{{cite journal |vauthors=Puntis S, Minichino A, De Crescenzo F, Cipriani A, Lennox B, Harrison R |title=Specialised early intervention teams for recent-onset psychosis |journal=Cochrane Database Syst Rev |volume=11 |issue=11 |pages=CD013288 |date=November 2020 |pmid=33135811 |doi=10.1002/14651858.CD013288.pub2 |pmc=8092671 | quote=p. 22: There is low-certainty evidence for the use of SEl services in comparison to TAU for a small reduction in psychiatric hospitalisation, and moderate-certainty evidence of a large effect of reduction in disengagement from mental health services. There is moderate-certainty evidence that SEI results in a small reduction of positive (hallucinations, delusions and disordered thinking) and negative symptoms (social withdrawal, flat or blunted affect, and poverty of speech) and low-certainty evidence that it greatly increases satisfaction in care, while there is low-certainty evidence that it improves general functioning and the likelihood of recovery. These effects were only observed during treatment and there was no evidence that outcomes are improved after the treatment has finished, although these were based on only one trial.}}</ref>
Factors such as ] and ] also appear to be involved in increasing the risk of schizophrenia or schizophrenia relapse, perhaps due to the high levels of stress they engender, or faults in diagnostic procedure/assumptions. Racism in society, including in diagnostic practices, and/or the stress of living in a different culture, may explain why minority communities have shown higher rates of schizophrenia than members of the same ethnic groups resident in their home country. The "social drift hypothesis" suggests that the functional problems related to schizophrenia, or the stigma and prejudice attached to them, can result in more limited employment and financial opportunities, so that the causal pathway goes from mental health problems to poverty, rather than, or in addition to, the other direction. Some argue that ] and the long-term unemployed and homeless are simply being stigmatised.


] may reduce the risk of psychosis in those at high risk after a year<ref>{{cite journal | vauthors = Stafford MR, Jackson H, Mayo-Wilson E, Morrison AP, Kendall T | title = Early interventions to prevent psychosis: systematic review and meta-analysis | journal = BMJ | volume = 346 | page = f185 | date = January 2013 | pmid = 23335473 | pmc = 3548617 | doi = 10.1136/bmj.f185 }}</ref> and is recommended in this group, by the ] (NICE).<ref name="NICE2014">{{cite web|title=Psychosis and schizophrenia in adults: treatment and management |url=http://www.nice.org.uk/nicemedia/live/14382/66534/66534.pdf |publisher = ] (NICE) |access-date=19 April 2014 |pages=4–34|date=March 2014 |archive-url=https://web.archive.org/web/20140420070946/http://www.nice.org.uk/nicemedia/live/14382/66534/66534.pdf |archive-date=20 April 2014 }}</ref> Another preventive measure is to avoid drugs that have been associated with development of the disorder, including ], cocaine, and ].<ref name="BMJ07" />
One particularly stable and replicable finding has been the association between living in an ] environment and schizophrenia diagnosis, even after factors such as ], ] and size of ] have been controlled for.<ref name="fn_19"> Does the urban environment cause psychosis? ''British Journal of Psychiatry'', 184 (4), 287&ndash;288.<br></ref> A recent study of 4.4 million men and women in ] found an alleged 68%&ndash;77% increased risk of diagnosed ] for people living in the most urbanized environments, a significant proportion of which is likely to be described as schizophrenia.<ref name="fn_20"> Urbanisation and incidence of psychosis and depression: Follow-up study of 4.4 million women and men in Sweden. ''British Journal of Psychiatry'', 184 (4), 293&ndash;298.<br></ref>


Antipsychotics are prescribed following a first-episode psychosis, and following remission, a preventive maintenance use is continued to avoid relapse. However, it is recognized that some people do recover following a single episode and that long-term use of antipsychotics will not be needed but there is no way of identifying this group.<ref name=Taylor2019>{{cite journal |vauthors=Taylor M, Jauhar S |title=Are we getting any better at staying better? The long view on relapse and recovery in first episode nonaffective psychosis and schizophrenia |journal=Therapeutic Advances in Psychopharmacology |volume=9 |date=September 2019|page=204512531987003 |pmid=31523418|doi=10.1177/2045125319870033 |pmc=6732843 }}</ref>
One curious finding is that people diagnosed with schizophrenia are more likely to have been born in ] or ]<ref name="fn_21"> A ] and meta-analysis of Northern Hemisphere season of birth studies in schizophrenia. ''Schizophrenia Bulletin'', 29 (3), 587&ndash;93.<br></ref> (at least in the ]). However, the effect is not large. Some researchers postulate that the correlation is due to viral infections during the third trimester (4-6 months) of pregnancy.


==Management==
A study by Sweden's Karolinska Institute and Bristol University in the UK, looked at the medical records of over 700,000 people and calculated that 15.5% of cases of schizophrenia seen in the group may have been due to the patient having a father who was aged over 30 years at their birth, the researchers argue this is due to build up of mutations in the sperm of elder fathers.<ref name="fn_79" />
{{Main|Management of schizophrenia}}
The primary treatment of schizophrenia is the use of ], often in combination with ] and ]s.<ref name=Lancet2009/><ref>{{cite journal | vauthors = Weiden PJ |title=Beyond Psychopharmacology: Emerging Psychosocial Interventions for Core Symptoms of Schizophrenia. |journal=Focus (American Psychiatric Publishing) |volume=14 |issue=3 |pages=315–327 |date=July 2016 |pmid=31975812|doi=10.1176/appi.focus.20160014|pmc=6526802 }}</ref> Community support services including drop-in centers, visits by members of a ], ],<ref>{{cite journal | vauthors = McGurk SR, Mueser KT, Feldman K, Wolfe R, Pascaris A | title = Cognitive training for supported employment: 2–3 year outcomes of a randomized controlled trial | journal = The American Journal of Psychiatry | volume = 164 | issue = 3 | pages = 437–441 | date = March 2007 | pmid = 17329468 | doi = 10.1176/appi.ajp.164.3.437 }}</ref> and support groups are common. The time between the onset of psychotic symptoms to being given treatment – the duration of untreated psychosis (DUP) – is associated with a poorer outcome in both the short term and the long term.<ref>{{cite journal | vauthors = Souaiby L, Gaillard R, Krebs MO |title= |journal=Encephale |volume=42 |issue=4 |pages=361–366 |date=August 2016|pmid=27161262 |doi=10.1016/j.encep.2015.09.007 }}</ref>


] or ] admission to hospital may be imposed by doctors and courts who deem a person to be having a severe episode. In the UK, large mental hospitals termed asylums began to be closed down in the 1950s with the advent of antipsychotics, and with an awareness of the negative impact of long-term hospital stays on recovery.<ref name=Killaspy2014>{{cite journal |vauthors=Killaspy H|title= Contemporary mental health rehabilitation|journal=East Asian Archives of Psychiatry|volume=24 | issue=3|pages=89–94|date=September 2014|pmid = 25316799}}</ref> This process was known as ], and community and supportive services were developed to support this change. Many other countries followed suit with the US starting in the 60s.<ref>{{cite journal | vauthors = Fuller Torrey E | title = Deinstitutionalization and the rise of violence. | journal = CNS Spectrums | date = June 2015 | volume = 20 | issue = 3 | pages = 207–214 | doi = 10.1017/S1092852914000753 | pmid = 25683467| s2cid = 22210482 }}</ref> There still remain a smaller group of people who do not improve enough to be discharged.<ref name=Killaspy2014/><ref name=Capdevielle2009/> In some countries that lack the necessary supportive and social services, long-term hospital stays are more usual.<ref name=Narayan2012/>
===Neurobiological influences===
====Early neurodevelopment====
It is also thought that processes in early ] are important, particularly during pregnancy. For example, women who were pregnant during the ], where many people were close to starvation, had a higher chance of having a child who would later develop schizophrenia.<ref name="fn_22"> Schizophrenia after prenatal famine. Further evidence. ''Archives of General Psychiatry'', 53(1), 25&ndash;31.<br></ref> Similarly, studies of ] mothers who were pregnant when they found out that their husbands had been killed during the ] of 1939&ndash;1940 have shown that their children were much more likely to develop schizophrenia when compared with mothers who found out about their husbands' death after pregnancy,<ref name="fn_23"> Prenatal loss of father and psychiatric disorders. ''Archives of General Psychiatry'', 35(4), 429&ndash;31.<br></ref> suggesting that even ] in the mother may have an effect. Furthermore, there is now significant evidence that ] exposure to infections increases the risk for developing schizophrenia later in life, providing additional evidence for a link between developmental pathology and risk of developing the condition.<ref name="fn_73"> Prenatal infection as a risk factor for schizophrenia. ''Schizophrenia Bulletin'', 32 (2), 200-2.<br></ref>


===Medication===
Some researchers have proposed that environmental influences during childhood also interact with neurobiological risk factors to influence the likelihood of developing schizophrenia later in life. The neurological development of children is considered sensitive to features of dysfunctional social settings, such as trauma, violence, lack of warmth in personal relationships and hostility. These have all been found to be risk factors for the later development of schizophrenia. Research has suggested that effects of the childhood environment, favorable or unfavorable, interact with genetics and the processes of neurodevelopment, with long-term consequences for brain function. Consequently, this is thought to influence the underlying vulnerability for psychosis later in life, particularly during the adult years.<ref name="fn_24"> The contribution of early traumatic events to schizophrenia in some patients: a traumagenic neurodevelopmental model. ''Psychiatry'', 64, 319-45. ()<br></ref>
] (trade name Risperdal) is a common ] medication.]]


The first-line treatment for schizophrenia is an antipsychotic. The first-generation antipsychotics, now called ], like ], are ]s that block D<sub>2</sub> receptors, and affect the ] of ]. Those brought out later, the second-generation antipsychotics known as ], including ] and ], can also have an effect on another neurotransmitter, ]. Antipsychotics can reduce the symptoms of anxiety within hours of their use, but, for other symptoms, they may take several days or weeks to reach their full effect.<ref name=RAISE/><ref name=nhsTreatment/> They have little effect on negative and cognitive symptoms, which may be helped by additional psychotherapies and medications.<ref>{{cite journal | vauthors = Ortiz-Orendain J, Covarrubias-Castillo SA, Vazquez-Alvarez AO, Castiello-de Obeso S, Arias Quiñones GE, Seegers M, Colunga-Lozano LE | title = Modafinil for people with schizophrenia or related disorders | journal = The Cochrane Database of Systematic Reviews | volume = 12 | page = CD008661 | date = December 2019 | issue = 12 | pmid = 31828767 | pmc = 6906203 | doi = 10.1002/14651858.CD008661.pub2 }}</ref> There is no single antipsychotic suitable for first-line treatment for everyone, as responses and tolerances vary between people.<ref>{{cite journal | vauthors = Lally J, MacCabe JH | title = Antipsychotic medication in schizophrenia: a review | journal = British Medical Bulletin | volume = 114 | issue = 1 | pages = 169–179 | date = June 2015 | pmid = 25957394 | doi = 10.1093/bmb/ldv017 | doi-access = }}</ref> Stopping medication may be considered after a single psychotic episode where there has been a full recovery with no symptoms for twelve months. Repeated relapses worsen the long-term outlook and the risk of relapse following a second episode is high, and long-term treatment is usually recommended.<ref>{{cite journal | vauthors = Keks N, Schwartz D, Hope J | title = Stopping and switching antipsychotic drugs | journal = Australian Prescriber | volume = 42 | issue = 5 | pages = 152–157 | date = October 2019 | pmid = 31631928 | pmc = 6787301 | doi = 10.18773/austprescr.2019.052 }}</ref><ref name=Harrow2013>{{cite journal | vauthors = Harrow M, Jobe TH | title = Does long-term treatment of schizophrenia with antipsychotic medications facilitate recovery? | journal = Schizophrenia Bulletin | volume = 39 | issue = 5 | pages = 962–5 | date = September 2013 | pmid = 23512950 | pmc = 3756791 | doi = 10.1093/schbul/sbt034 }}</ref>
] study<ref name="fn_25"> Reduced prefrontal activity predicts exaggerated striatal dopaminergic function in schizophrenia. ''Nature Neuroscience'', 5, 267-71.<br></ref> suggests that the less the ]s are activated (<font color="red">red</font>) during a ] task, the greater the increase in abnormal ] activity in the ] (<font color="green">green</font>), thought to be related to the ]s in schizophrenia.]]


About half of those with schizophrenia will respond favourably to antipsychotics, and have a good return of functioning.<ref>{{cite journal |vauthors=Elkis H, Buckley PF |title=Treatment-Resistant Schizophrenia |journal=The Psychiatric Clinics of North America |volume=39 |issue=2 |pages=239–65 |date=June 2016 |pmid=27216902|doi=10.1016/j.psc.2016.01.006}}</ref> However, positive symptoms persist in up to a third of people. Following two trials of different antipsychotics over six weeks, that also prove ineffective, they will be classed as having treatment-resistant schizophrenia (TRS), and ] will be offered.<ref>{{cite journal |vauthors=Gillespie AL, Samanaite R, Mill J, Egerton A, MacCabe JH |title=Is treatment-resistant schizophrenia categorically distinct from treatment-responsive schizophrenia? a systematic review |journal=BMC Psychiatry |volume=17 |issue=1 |page=12 |date=13 January 2017 |pmid=28086761 |doi=10.1186/s12888-016-1177-y|pmc=5237235 |doi-access=free }}</ref><ref name=Siskind2017/> Clozapine is of benefit to around half of this group although it has the potentially serious side effect of ] (lowered ] count) in less than 4% of people.<ref name=Lancet2009/><ref name=BMJ07/><ref>{{cite journal | vauthors = Essali A, Al-Haj Haasan N, Li C, Rathbone J | title = Clozapine versus typical neuroleptic medication for schizophrenia | journal = The Cochrane Database of Systematic Reviews | issue = 1 | page = CD000059 | date = January 2009 | volume = 2009 | pmid = 19160174 | doi = 10.1002/14651858.CD000059.pub2 | pmc = 7065592 }}</ref>
====Role of dopamine====
In adult life, particular importance has been placed upon the function (or malfunction) of dopamine in the ] in the brain. This theory, known as the ], largely resulted from the accidental finding that a drug group which blocks dopamine function, known as the ], reduced psychotic symptoms. These drugs have now been developed further and antipsychotic medication is commonly used as a first line treatment.


About 30 to 50 percent of people with schizophrenia do not accept that they have an illness or comply with their recommended treatment.<ref>{{cite journal | vauthors = Baier M | title = Insight in schizophrenia: a review | journal = Current Psychiatry Reports | volume = 12 | issue = 4 | pages = 356–361 | date = August 2010 | pmid = 20526897 | doi = 10.1007/s11920-010-0125-7 | s2cid = 29323212 }}</ref> For those who are unwilling or unable to take medication regularly, ] of antipsychotics may be used,<ref>{{cite journal | vauthors = Peters L, Krogmann A, von Hardenberg L, Bödeker K, Nöhles VB, Correll CU | title = Long-Acting Injections in Schizophrenia: a 3-Year Update on Randomized Controlled Trials Published January 2016 – March 2019 | journal = Current Psychiatry Reports | volume = 21 | issue = 12 | pages = 124 | date = November 2019 | pmid = 31745659 | doi = 10.1007/s11920-019-1114-0 | s2cid = 208144438 }}</ref> which reduce the risk of relapse to a greater degree than oral medications.<ref>{{cite journal | vauthors = Leucht S, Tardy M, Komossa K, Heres S, Kissling W, Salanti G, Davis JM | title = Antipsychotic drugs versus placebo for relapse prevention in schizophrenia: a systematic review and meta-analysis | journal = Lancet | volume = 379 | issue = 9831 | pages = 2063–2071 | date = June 2012 | pmid = 22560607 | doi = 10.1016/S0140-6736(12)60239-6 | s2cid = 2018124 }}</ref> When used in combination with psychosocial interventions, they may improve long-term ] to treatment.<ref name=Depo06>{{cite journal | vauthors = McEvoy JP | title = Risks versus benefits of different types of long-acting injectable antipsychotics | journal = The Journal of Clinical Psychiatry | volume = 67 | issue = Suppl 5 | pages = 15–18 | year = 2006 | pmid = 16822092 }}</ref>
However, this theory is now thought to be overly simplistic as a complete explanation, partly because newer antipsychotic medication (called ] medication) is equally effective as older medication (called ] medication), but also affects ] function and may have slightly less of a ] blocking effect. Psychiatrist ] has also argued that ] have promoted certain oversimplified biological theories of mental illness to promote their own sales of biological treatments.<ref name="fn_26">Healy, D. (2002) ''The Creation of Psychopharmacology''. Cambridge, MA: Harvard University Press. ISBN 0-674-00619-4<br></ref>


The ] medication ] (Cobenfy) was approved for medical use in the United States in September 2024.<ref name="FDA PR 20240926">{{cite press release | title=FDA Approves Drug with New Mechanism of Action for Treatment of Schizophrenia | website=U.S. ] (FDA) | date=26 September 2024 | url=https://www.fda.gov/news-events/press-announcements/fda-approves-drug-new-mechanism-action-treatment-schizophrenia | access-date=27 September 2024 | archive-date=27 September 2024 | archive-url=https://web.archive.org/web/20240927004824/https://www.fda.gov/news-events/press-announcements/fda-approves-drug-new-mechanism-action-treatment-schizophrenia | url-status=live }} {{PD-notice}}</ref><ref>{{cite press release | title=U.S. Food and Drug Administration Approves Bristol Myers Squibb's Cobenfy (xanomeline and trospium chloride), a First-In-Class Muscarinic Agonist for the Treatment of Schizophrenia in Adults | publisher=Bristol Myers Squibb | via=Business Wire | date=27 September 2024 | url=https://www.businesswire.com/news/home/20240925382351/en/U.S.-Food-and-Drug-Administration-Approves-Bristol-Myers-Squibb%E2%80%99s-COBENFY%E2%84%A2-xanomeline-and-trospium-chloride-a-First-In-Class-Muscarinic-Agonist-for-the-Treatment-of-Schizophrenia-in-Adults | access-date=27 September 2024}}</ref> It is the first ] approved by the US ] (FDA) to treat schizophrenia.<ref name="FDA PR 20240926" />
====Role of glutamate and the NMDA receptor====
Interest has also focused on the neurotransmitter ] and the reduced function of the ] in the development of schizophrenia. This theory has largely been suggested by abnormally low levels of glutamate receptors found in postmortem brains of people previously diagnosed with schizophrenia<ref name="fn_27"> Molecular aspects of glutamate dysregulation: implications for schizophrenia and its treatment. ''Pharmacology and Therapeutics'', 97(2), 153-79.<br></ref> and the discovery that the glutamate blocking drugs such as ] and ] can mimic the symptoms and cognitive problems associated with the condition.<ref name="fn_59"> Effects of ketamine in normal and schizophrenic volunteers. ''Neuropsychopharmacology'', 25(4), 455-67.<br></ref> The fact that reduced glutamate function is linked to poor performance on tests requiring ] and ] function and that glutamate can affect ] function, all of which have been implicated in schizophrenia, have suggested the ] as an increasingly popular explanation.<ref name="fn_28"> Converging evidence of NMDA receptor hypofunction in the pathophysiology of schizophrenia. ''Annals of the New York Academy of Sciences'', 1003, 318-27.<br></ref> Further support of this theory has come from trials showing the efficacy of molecules, which are coagonists at the NMDA receptor complex, in reducing schizophrenic symptoms. The precursors D-serine, glycine, and D-cycloserine all enhance NMDA function through the glycine co-agonist site. Several placebo controlled trials have shown a reduction mainly in negative symptoms with high dose therapy.<ref name="fn_60"> Glutamatergic drugs for schizophrenia: a systematic review and meta-analysis. ''Schizophr Res'', 72:225-34.<br></ref> Currently type 1 glycine transporter inhibitors are in late-state preclinical for the treatment of schizophrenia. They increase glycine concentrations in the brain thus causing increased NMDA receptor activation and a reduction in symptoms.<ref name="fn_61"> The Glycine Transporter Type 1 Inhibitor. ''The Journal of Neuroscience'', 23 (20), 7586-7591.<br></ref>


Negative and cognitive symptoms are an unmet clinical need in antipsychotic-based treatment approaches. Psychostimulant drugs have been found effective in the treatment of negative symptoms, but are rarely prescribed due to concerns about the excacerbation of positive symptoms.<ref>{{Cite journal |last1=Lindenmayer |first1=Jean-Pierre |last2=Nasrallah |first2=Henry |last3=Pucci |first3=Michael |last4=James |first4=Steven |last5=Citrome |first5=Leslie |date=2013-07-01 |title=A systematic review of psychostimulant treatment of negative symptoms of schizophrenia: Challenges and therapeutic opportunities |url=https://www.sciencedirect.com/science/article/abs/pii/S0920996413001655 |journal=Schizophrenia Research |volume=147 |issue=2 |pages=241–252 |doi=10.1016/j.schres.2013.03.019 |issn=0920-9964}}</ref> It is possible that low-dose psychedelic therapies could be of benefit in schizophrenia through their prosocial and procognitive effects, although there is a serious risk that high dose psychedelic therapies could lead to worsening of positive symptoms.<ref>{{Cite journal |last1=Sapienza |first1=Jacopo |last2=Martini |first2=Francesca |last3=Comai |first3=Stefano |last4=Cavallaro |first4=Roberto |last5=Spangaro |first5=Marco |last6=De Gregorio |first6=Danilo |last7=Bosia |first7=Marta |date=2024-09-18 |title=Psychedelics and schizophrenia: a double-edged sword |url=https://www.nature.com/articles/s41380-024-02743-x |journal=Molecular Psychiatry |language=en |pages=1–14 |doi=10.1038/s41380-024-02743-x |pmid=39294303 |issn=1476-5578}}</ref>
====Anatomy and physiology of the brain====
Much recent research has focused on differences in structure or function in certain brain areas in people diagnosed with schizophrenia.


====Adverse effects====
Early evidence for differences in the neural structure came from the discovery of ] enlargement in people diagnosed with schizophrenia, for whom negative symptoms were most prominent.<ref name="fn_29"> Cerebral ventricular size and cognitive impairment in chronic schizophrenia. ''Lancet'', 30;2 (7992), 924-6.<br></ref> However, this finding has not proved particularly reliable on the level of the individual person, with considerable variation between patients. A letter to the editor of the '']'' links ventricular enlargement with exposure to antipsychotic drugs.<ref>http://ajp.psychiatryonline.org/cgi/content/full/156/11/1843-b</ref>
{{Further information|Antipsychotic#Adverse effects}}


], including ], are associated with all commercially available ] to varying degrees.<ref name=Chow2020>{{cite journal |vauthors=Chow CL, Kadouh NK, Bostwick JR, VandenBerg AM |date=June 2020 |title=Akathisia and Newer Second-Generation Antipsychotic Drugs: A Review of Current Evidence |url= |journal=Pharmacotherapy |volume=40 |issue=6 |pages=565–574 |doi=10.1002/phar.2404 |pmid=32342999|hdl=2027.42/155998 |s2cid=216596357 |hdl-access=free }}</ref>{{Rp|page=566|quote=However, EPS, particularly akathisia, occurs, to some degree, with all commercially available SGAs.}} There is little evidence that second generation antipsychotics have reduced levels of extrapyramidical symptoms compared to typical antipsychotics.<ref name=Chow2020/>{{Rp|page=566|quote=Furthermore, previous meta-analyses and systematic reviews comparing the safety and tolerability of FGAs and SGAs have found little evidence to support the notion that as a class, SGAs pose a reduced risk for EPS com- pared with FGAs. However, high-potency FGAs do tend to pose the greatest risk for EPS.}} ] can occur due to long-term use of antipsychotics, developing after months or years of use.<ref>{{cite journal |vauthors=Carbon M, Kane JM, Leucht S, Correll CU |date=October 2018 |title=Tardive dyskinesia risk with first- and second-generation antipsychotics in comparative randomized controlled trials: a meta-analysis |journal=World Psychiatry |volume=17 |issue=3 |pages=330–340 |doi=10.1002/wps.20579 |pmc=6127753 |pmid=30192088}}</ref> The antipsychotic ] is also associated with ] (including ]), ], and ].
More recent studies have shown a large number of differences in brain structure between people with and without diagnoses of schizophrenia.<ref name="fn_30"> Review of cognition and brain structure in schizophrenia: profiles, longitudinal course, and effects of treatment. ''Psychiatric Clinics of North America'', 27 (1), 1-18, vii.<br></ref> However, as with earlier studies, many of these differences are only reliably detected when comparing groups of people, and are unlikely to predict any differences in brain structure of an individual person with schizophrenia.


===Psychosocial interventions===
Studies using ]s and ] technologies such as ] and ] to examine functional differences in brain activity have shown that differences seem to most commonly occur in the ]s, ], and ]s.<ref name="fn_31">Green, M.F. (2001) ''Schizophrenia Revealed: From Neurons to Social Interactions''. New York: W.W. Norton. ISBN 0-393-70334-7<br></ref> These differences are heavily linked to the ]s which often occur with schizophrenia, particularly in areas of ], ], ], ] and ].
{{Further|Management of schizophrenia#Psychosocial}}
A number of psychosocial interventions that include several types of ] may be useful in the treatment of schizophrenia such as: ],<ref name=Pharoah2010>{{cite journal | vauthors = Pharoah F, Mari J, Rathbone J, Wong W | title = Family intervention for schizophrenia | journal = The Cochrane Database of Systematic Reviews | volume = 12 | issue = 12 | pages = CD000088 | date = December 2010 | pmid = 21154340 | pmc = 4204509 | doi = 10.1002/14651858.CD000088.pub2 | veditors = Pharoah F }}</ref> ], cognitive remediation therapy (CRT),<ref>{{cite journal | vauthors = Bellani M, Ricciardi C, Rossetti MG, Zovetti N, Perlini C, Brambilla P | title = Cognitive remediation in schizophrenia: the earlier the better? | journal = Epidemiology and Psychiatric Sciences | volume = 29 | issue = | pages = e57 | date = September 2019 | pmid = 31556864 | pmc = 8061237 | doi = 10.1017/S2045796019000532 }}</ref> cognitive behavioral therapy (CBT), and ].<ref>{{cite journal | vauthors = Philipp R, Kriston L, Lanio J, Kühne F, Härter M, Moritz S, Meister R | title = Effectiveness of metacognitive interventions for mental disorders in adults-A systematic review and meta-analysis (METACOG) | journal = Clinical Psychology & Psychotherapy | volume = 26 | issue = 2 | pages = 227–240 | date = March 2019 | pmid = 30456821 | doi = 10.1002/cpp.2345 | s2cid = 53872643 }}</ref><ref>{{cite journal | vauthors = Rouy M, Saliou P, Nalborczyk L, Pereira M, Roux P, Faivre N | title = Systematic review and meta-analysis of metacognitive abilities in individuals with schizophrenia spectrum disorders | journal = Neuroscience and Biobehavioral Reviews | volume = 126 | issue = | pages = 329–337 | date = July 2021 | pmid = 33757817 | doi = 10.1016/j.neubiorev.2021.03.017 | s2cid = 232288918 | url = https://hal.archives-ouvertes.fr/hal-03178486/file/2020.12.03.20243113v1.full.pdf }}</ref> Skills training, help with substance use, and weight management – often needed as a side effect of an antipsychotic – are also offered.<ref>{{cite journal | vauthors = Dixon LB, Dickerson F, Bellack AS, Bennett M, Dickinson D, Goldberg RW, Lehman A, Tenhula WN, Calmes C, Pasillas RM, Peer J, Kreyenbuhl J | title = The 2009 schizophrenia PORT psychosocial treatment recommendations and summary statements | journal = Schizophrenia Bulletin | volume = 36 | issue = 1 | pages = 48–70 | date = January 2010 | pmid = 19955389 | pmc = 2800143 | doi = 10.1093/schbul/sbp115 }}</ref> In the US, interventions for first episode psychosis have been brought together in an overall approach known as ] (CSC) and also includes support for education.<ref name=RAISE/> In the UK ''care across all phases'' is a similar approach that covers many of the treatment guidelines recommended.<ref name=NICE2014/> The aim is to reduce the number of relapses and stays in the hospital.<ref name=Pharoah2010/>


Other support services for education, employment, and housing are usually offered. For people with severe schizophrenia, who are discharged from a stay in the hospital, these services are often brought together in an integrated approach to offer support in the community away from the hospital setting. In addition to medicine management, housing, and finances, assistance is given for more routine matters such as help with shopping and using public transport. This approach is known as ] (ACT) and has been shown to achieve positive results in symptoms, social functioning and quality of life.<ref>{{cite journal | vauthors = Bond GR, Drake RE | title = The critical ingredients of assertive community treatment. | journal = World Psychiatry | date = June 2015 | volume = 14 | issue = 2 | pages = 240–242 | doi = 10.1002/wps.20234 | pmid = 26043344| pmc = 4471983 }}</ref><ref>{{cite journal | vauthors = Smeerdijk M | title = . | journal = Tijdschrift voor Psychiatrie | date = 2017 | volume = 59 | issue = 8 | pages = 466–473 | pmid = 28880347}}</ref> Another more intense approach is known as ''intensive care management'' (ICM). ICM is a stage further than ACT and emphasises support of high intensity in smaller caseloads, (less than twenty). This approach is to provide long-term care in the community. Studies show that ICM improves many of the relevant outcomes including social functioning.<ref>{{cite journal | vauthors = Dieterich M | title = Intensive case management for severe mental illness | journal=The Cochrane Database of Systematic Reviews | date = 6 January 2017 | volume = 1 | issue = 1 | page = CD007906 | doi = 10.1002/14651858.CD007906.pub3 | pmid = 28067944| pmc = 6472672 }}</ref>
] (EEG) recordings of persons with schizophrenia performing perception oriented tasks showed an absence of ] activity in the brain, indicating weak integration of critical neural networks in the brain.<ref name="fn_32"> Neural synchrony indexes disordered perception and cognition in schizophrenia. ''Proceedings of the National Academy of Sciences'', 101, 17288-93. ()<br></ref> Those who experienced intense hallucinations, delusions and disorganized thinking showed the lowest frequency synchronization. None of the drugs taken by the persons scanned had moved neural synchrony back into the gamma frequency range. Gamma band and working memory alterations may be related to alterations in ]s that produced the neurotransmitter ]. Alterations in a subclass of GABAergic interneurons which produce the calcium-binding protein ] have been shown to exist in the dorsolateral prefrontal cortex in schizophrenia.<ref name="fn_33"> Cortical inhibitory neurons and schizophrenia. ''Nature Reviews Neuroscience'', 6, 312-324.<br></ref>


Some studies have shown little evidence for the effectiveness of CBT in either reducing symptoms or preventing relapse.<ref>{{cite journal | vauthors = Jauhar S, McKenna PJ, Radua J, Fung E, Salvador R, Laws KR | title = Cognitive-behavioural therapy for the symptoms of schizophrenia: systematic review and meta-analysis with examination of potential bias | journal = The British Journal of Psychiatry | volume = 204 | issue = 1 | pages = 20–29 | date = January 2014 | pmid = 24385461 | doi = 10.1192/bjp.bp.112.116285 | type = Review | doi-access = free }}</ref><ref name=Jones2018>{{cite journal | vauthors = Jones C, Hacker D, Meaden A, Cormac I, Irving CB, Xia J, Zhao S, Shi C, Chen J | title = Cognitive behavioural therapy plus standard care versus standard care plus other psychosocial treatments for people with schizophrenia | journal = The Cochrane Database of Systematic Reviews | volume = 11 | issue = 11 | pages = CD008712 | date = November 2018 | pmid = 30480760 | pmc = 6516879 | doi = 10.1002/14651858.CD008712.pub3 }}</ref> However, other studies have found that CBT does improve overall psychotic symptoms (when in use with medication) and it has been recommended in Canada, but has been seen to have no effect on social function, relapse, or quality of life.<ref>{{cite journal | title = Cognitive Behavioural Therapy for Psychosis: A Health Technology Assessment| journal = Ontario Health Technology Assessment Series | date = 2018 |volume = 18 | issue = 5 |pages = 1–141 | pmid = 30443277 | pmc = 6235075 | author = Health Quality Ontario }}</ref> In the UK it is recommended as an add-on therapy in the treatment of schizophrenia.<ref name=nhsTreatment/><ref name=Jones2018/> ] are seen to improve negative symptoms in some people, and are recommended by NICE in the UK.<ref name=nhsTreatment>{{cite web | title = Schizophrenia – Treatment | url = https://www.nhs.uk/conditions/schizophrenia/treatment/ | publisher= UK ] | access-date = 8 January 2020 | date = 23 October 2017}}</ref> This approach is criticised as having not been well-researched,<ref>{{cite journal | vauthors = Ruddy R, Milnes D | title = Art therapy for schizophrenia or schizophrenia-like illnesses | journal = The Cochrane Database of Systematic Reviews | issue = 4 | page = CD003728 | date = October 2005 | pmid = 16235338 | doi = 10.1002/14651858.CD003728.pub2 | url = http://www.cochrane.org/reviews/en/ab003728.html | archive-url = https://web.archive.org/web/20111027132811/http://www2.cochrane.org/reviews/en/ab003728.html | df = dmy-all | url-status=live | archive-date = 27 October 2011 }}</ref><ref>{{cite journal | vauthors = Ruddy RA, Dent-Brown K | title = Drama therapy for schizophrenia or schizophrenia-like illnesses | journal = The Cochrane Database of Systematic Reviews | issue = 1 | page = CD005378 | date = January 2007 | pmid = 17253555 | doi = 10.1002/14651858.CD005378.pub2 | url = http://www.cochrane.org/reviews/en/ab005378.html | archive-url = https://web.archive.org/web/20110825024045/http://www2.cochrane.org/reviews/en/ab005378.html | df = dmy-all | url-status=live | archive-date = 25 August 2011 }}</ref> and arts therapies are not recommended in Australian guidelines for example.<ref>{{cite journal |vauthors=Galletly C, Castle D, Dark F, et al |title=Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for the management of schizophrenia and related disorders |journal=Aust N Z J Psychiatry |volume=50 |issue=5 |pages=410–472 |date=May 2016 |pmid=27106681 |doi=10.1177/0004867416641195 |s2cid=6536743 |url=|doi-access=free }}</ref> ], in which people with ] of schizophrenia, provide help to each other, is of unclear benefit.<ref>{{cite journal |vauthors= Chien WT, Clifton AV, Zhao S, Lui S |title=Peer support for people with schizophrenia or other serious mental illness. |journal=The Cochrane Database of Systematic Reviews |date=4 April 2019 |volume=4 |issue=6 |page=CD010880 |doi=10.1002/14651858.CD010880.pub2 |pmid=30946482|pmc=6448529 }}</ref>
==Incidence and prevalence==
In the western world, schizophrenia is typically diagnosed in late adolescence or early adulthood. In the western world, it is found approximately equally in men and women, though the onset tends to be later in women, who also tend to have a better course and outcome. Although rare, there are also instances of ] and ] that occurs in the elderly.


===Other===
The lifetime ] of schizophrenia is commonly given at 1%; however, a recent review of studies from around the world estimated it to be 0.55%.<ref name="fn_34"> Prevalence and incidence studies of schizophrenic disorders: a ] of the literature. ''Canadian Journal of Psychiatry'', 47(9), 833&ndash;43.<br></ref> The same study also found that prevalence may vary greatly from country to country, despite the received wisdom that schizophrenia occurs at the same rate throughout the world. It is worth noting however, that this may be in part due to differences in the way schizophrenia is diagnosed. The ] of schizophrenia was given as a range of between 7.5 and 16.3 cases per year per 100,000 population.
Exercise including aerobic exercise has been shown to improve positive and negative symptoms, cognition, working memory, and improve quality of life.<ref name=Girdler2019>{{cite journal | vauthors =Girdler SJ, Confino JE, Woesner ME | title = Exercise as a Treatment for Schizophrenia: A Review. |journal= Psychopharmacology Bulletin | date = 15 February 2019 | volume = 49 | issue = 1 | pages=56–69 | pmid=30858639| pmc = 6386427 }}</ref><ref name=Firth2017>{{cite journal | vauthors = Firth J | title = Aerobic Exercise Improves Cognitive Functioning in People With Schizophrenia: A Systematic Review and Meta-Analysis | journal = Schizophrenia Bulletin | date = 1 May 2017 | volume = 43 | issue = 3 | pages = 546–556 | doi = 10.1093/schbul/sbw115 | pmid = 27521348| pmc = 5464163 }}</ref> Exercise has also been shown to increase the volume of the ] in those with schizophrenia. A decrease in hippocampal volume is one of the factors linked to the development of the disease.<ref name=Girdler2019/> However, there still remains the problem of increasing motivation for, and maintaining participation in physical activity.<ref>{{cite journal | vauthors = Tréhout M, Dollfus S |title = . | journal = L'Encéphale | date = December 2018 | volume = 44 | issue = 6 | pages = 538–547 | doi=10.1016/j.encep.2018.05.005 | pmid = 29983176|s2cid = 150334210 }}</ref> Supervised sessions are recommended.<ref name=Firth2017/> In the UK healthy eating advice is offered alongside exercise programs.<ref>{{cite web |title=Quality statement 7: Promoting healthy eating, physical activity and smoking cessation {{!}} Psychosis and schizophrenia in adults |date=12 February 2015 |url=https://www.nice.org.uk/guidance/qs80/chapter/Quality-statement-7-Promoting-healthy-eating-physical-activity-and-smoking-cessation |publisher= UK ]}}</ref>


An inadequate diet is often found in schizophrenia, and associated vitamin deficiencies including those of ], and ] are linked to the risk factors for the development of schizophrenia and for early death including heart disease.<ref name=Firth2018>{{cite journal | vauthors = Firth J, Carney R, Stubbs B, Teasdale SB, Vancampfort D, Ward PB, Berk M, Sarris J | title = Nutritional Deficiencies and Clinical Correlates in First-Episode Psychosis: A Systematic Review and Meta-analysis | journal = Schizophrenia Bulletin | volume = 44 | issue = 6 | pages = 1275–1292 | date = October 2018 | pmid = 29206972 | pmc = 6192507 | doi = 10.1093/schbul/sbx162 }}</ref><ref name=Rastogi2020>{{cite journal | vauthors = Rastogi A, Viani-Walsh D, Akbari S, Gall N, Gaughran F, Lally J | title = Pathogenesis and management of Brugada syndrome in schizophrenia: A scoping review | journal = General Hospital Psychiatry | volume = 67 | pages = 83–91 | date = October 2020 | pmid = 33065406 | pmc = 7537626 | doi = 10.1016/j.genhosppsych.2020.09.003 }}</ref> Those with schizophrenia possibly have the worst diet of all the mental disorders. Lower levels of folate and vitamin D have been noted as significantly lower in first episode psychosis.<ref name=Firth2018/> The use of supplemental folate is recommended.<ref>{{cite journal | vauthors = Martone G | title = Enhancement of recovery from mental illness with l-methylfolate supplementation | journal = Perspectives in Psychiatric Care | volume = 54 | issue = 2 | pages = 331–334 | date = April 2018 | pmid = 28597528 | doi = 10.1111/ppc.12227 | doi-access = free }}</ref> A ] has also been noted.<ref name=Firth2019>{{cite journal | vauthors = Firth J, Teasdale SB, Allott K, Siskind D, Marx W, Cotter J, Veronese N, Schuch F, Smith L, Solmi M, Carvalho AF, Vancampfort D, Berk M, Stubbs B, Sarris J | title = The efficacy and safety of nutrient supplements in the treatment of mental disorders: a meta-review of meta-analyses of randomized controlled trials | journal = World Psychiatry | volume = 18 | issue = 3 | pages = 308–324 | date = October 2019 | pmid = 31496103 | pmc = 6732706 | doi = 10.1002/wps.20672 }}</ref> ] is also often deficient and this is linked to worse symptoms. Supplementation with B vitamins has been shown to significantly improve symptoms, and to put in reverse some of the cognitive deficits.<ref name=Firth2018/> It is also suggested that the noted dysfunction in gut microbiota might benefit from the use of ].<ref name=Firth2019/>
Schizophrenia is also a major cause of ]. In a recent 14-country study,<ref name="fn_35">. Multiple-informant ranking of the disabling effects of different health conditions in 14 countries. '''', 354(9173), 111&ndash;115.<br></ref> active ] was ranked the third most disabling condition after ] and ] and before ] and ].

==Treatment==
===Medication and hospitalization===
Currently schizophrenia has not been cured although many psychiatrists and psychologists believe that it can be managed. The first line pharmacological therapy for schizophrenia is usually the use of ] medication <ref name="fn_72"> ''Schizophrenia. Full national clinical guideline on core interventions in primary and secondary care''. London: Gaskell and the British Psychological Society.<br></ref>. The concept of 'curing' schizophrenia is controversial as there are no clear criteria for what might constitute a ], although some criteria for the remission of symptoms have recently been suggested<ref name="fn_63"> Standardized remission criteria in schizophrenia. ''Acta Psychiatrica Scandinavica'', 113(2), 91-5.<br></ref>. Therefore, antipsychotic drugs are only thought to provide symptomatic relief from the positive symptoms of psychosis. The newer ] medications (such as ], ], ], ], ], ], and ]) are usually preferred over older ] medications (such as ] and ]) due to their favorable side-effect profile. Compared to the typical antipsychotics, the atypicals are associated with a lower incident rate of ] side effects (EPS) and ] (TD) although they are more likely to induce weight gain and so increase risk for ]-related diseases<ref name="fn_62"> Effectiveness of antipsychotic drugs in patients with chronic schizophrenia. ''The New England Journal of Medicine'', 353 (12), 1209-23.<br></ref>. It is still unclear whether newer drugs reduce the chances of developing the rare but potentially life-threatening ] (NMS). While the atypical antipsychotics are associated with less EPS and TD than the conventional antipsychotics, some of the agents in this class (especially olanzapine and clozapine) appear to be associated with metabolic side effects such as ], ] and ] that must be considered when choosing appropriate pharmacotherapy.

Atypical and typical antipsychotics are generally thought to be equivalent for the treatment of the positive symptoms of schizophrenia. It has been suggested by some researchers that the atypicals have some beneficial effects on negative symptoms and cognitive deficits associated with schizophrenia, although the clinical significance of these effects has yet to be established. However, recent reviews have suggested that typical antipsychotics, when dosed conservatively, may have similar effects to atypicals.<ref name="fn_36"> New generation antipsychotics versus low-potency conventional antipsychotics: a ] and meta-analysis. ''Lancet'', 361(9369), 1581-9.<br></ref> The atypical antipsychotics are much more costly as they are still within patent, whereas the older drugs are available in inexpensive generic forms. ] is a drug from a new class of antipsychotic drugs (variously named 'dopamine system stabilizers' or 'partial dopamine agonists'<ref name="fn_37"> Aripiprazole, an Antipsychotic With a Novel Mechanism of Action, and Risperidone vs Placebo in Patients With Schizophrenia and Schizoaffective Disorder. ''Archives of General Psychiatry'', 60(7), 681&ndash;90.<br></ref>) that have recently been developed and is now widely licensed to treat schizophrenia.

The efficacy of schizophrenia treatment is often assessed by using standardized assessment methods, one of the most common being the positive and negative syndrome scale (]).<ref name="fn_68"> The positive and negative syndrome scale (PANSS) for schizophrenia. ''Schizophrenia Bulletin'', 13(2), 261-76.<br></ref>

Hospitalization may occur with severe episodes. This can be voluntary or (if mental health legislation allows it) involuntary (called civil or ]). Mental health legislation may also allow people to be treated against their will. However, in many countries such legislation does not exist, or does not have the power to enforce involuntary hospitalization or treatment.

===Therapy and community support===
] or other forms of talk therapy may be offered, with cognitive behavioral therapy being the most frequently used. This may focus on the direct reduction of the symptoms, or on related aspects, such as issues of ], social functioning, and insight. Although the results of early trials with ] (CBT) were inconclusive<ref name="fn_38"> Cognitive behaviour therapy for schizophrenia. ''Cochrane Database of ]s'', (1), CD000524.<br></ref>, more recent reviews suggest that CBT can be an effective treatment for the psychotic symptoms of schizophrenia<ref name="fn_39"> The effect of cognitive behavioral treatment on the positive symptoms of schizophrenia spectrum disorders: a meta-analysis. ''Schizophrenia Research'', 77, 1-9.<br></ref>.

A relatively new approach has been the use of cognitive remediation therapy, a technique aimed at remediating the ]s sometimes present in schizophrenia. Based on techniques of ], early evidence has shown it to be cognitively effective, with some improvements related to measurable changes in brain activation as measured by ].<ref name="fn_40"> Effects on the brain of a psychological treatment: cognitive remediation therapy: functional magnetic resonance imaging in schizophrenia. ''British Journal of Psychiatry'', 181, 144-52.<br></ref>

] (also known as ECT or 'electroshock therapy') may be used in countries where it is legal. It is not considered a ] but may be prescribed in cases where other treatments have failed. ] has now become a rare procedure and is not a recommended treatment for schizophrenia.

Other support services may also be available, such as drop-in centers, visits from members of a 'community mental health team' or ] team, and patient-led support groups. In recent years the importance of service-user led recovery based movements has grown substantially throughout ] and ]. Groups such as the ] and more recently, the ], have developed a self-help approach that aims to provide support and assistance outside of the traditional medical model adopted by mainstream psychiatry. By avoiding framing personal experience in terms of criteria for ] or ], they aim to destigmatize the experience and encourage individual responsibility and a positive self-image.

In many non-Western societies, schizophrenia may be treated with more informal, community-led methods. A particularly sobering thought for Western psychiatry is that the outcome for people diagnosed with schizophrenia in non-Western countries may actually be much better<ref name="fn_41"> Outcome of schizophrenia: some transcultural observations with particular reference to developing countries. ''European Archives of Psychiatry and Clinical Neuroscience'', 244(5), 227&ndash;35.<br></ref> than for people in the West. The reasons for this recently discovered fact are still far from clear, although cross-cultural studies are being conducted to find out why.

A recent randomised controlled trial found that music therapy significantly improved symptom scores in a group of patients diagnosed with schizophrenia.<ref>
{{cite journal| quotes = Music therapy may provide a means of improving mental health among people with schizophrenia, but its effects in acute psychoses have not been explored | last = Crawford | first = Mike J. | authorlink = | coauthors = Talwar, Nakul, et al. | year = 2006 | month = November | title = Music therapy for in-patients with schizophrenia: Exploratory randomised controlled trial | journal = The British Journal of Psychiatry (2006) | volume = 189 | pages = 405-409 | url = http://bjp.rcpsych.org/cgi/content/abstract/189/5/405}}</ref> A notable early mention of the beneficial effect of music on mental illness was in 1621 by Robert Burton in ].<ref>Burton, R. . Cf. especially subsection 3, on and after line 3480, "Music a Remedy".</ref>

===Dietary supplements===
] (found naturally in foods such as oily fish, flax seeds, hemp seeds, walnuts and canola oil) have recently been studied as a treatment for schizophrenia. Although the number of research trials has been limited, the majority of randomized controlled trials have found omega-3 supplements to be effective when used as a dietary supplement.<ref name="fn_64"> Omega-3 fatty acids in the treatment of psychiatric disorders. ''Drugs'', 65(8), 1051-9.<br></ref>


==Prognosis== ==Prognosis==
{{Main|Prognosis of schizophrenia}}{{See also|Physical health in schizophrenia}}
] for any particular individual affected by schizophrenia is particularly hard to judge as treatment and access to treatment is continually changing, as new methods become available and medical recommendations change.
]s lost due to schizophrenia per 100,000&nbsp;inhabitants in 2004
{{Col-begin}}
{{Col-break}}
{{legend|#b3b3b3|no data}}
{{legend|#ffff65|≤&nbsp;185}}
{{legend|#fff200|185–197}}
{{legend|#ffdc00|197–207}}
{{legend|#ffc600|207–218}}
{{legend|#ffb000|218–229}}
{{legend|#ff9a00|229–240}}
{{Col-break}}
{{legend|#ff8400|240–251}}
{{legend|#ff6e00|251–262}}
{{legend|#ff5800|262–273}}
{{legend|#ff4200|273–284}}
{{legend|#ff2c00|284–295}}
{{legend|#cb0000|≥&nbsp;295}}
{{col-end}}]]
<!-- Life expectancy -->
Schizophrenia has great human and economic costs.<ref name=Lancet2016/> It decreases life expectancy by between 10<ref name=Laursen2014/><!-- Laursen2014 shows a range of 10-25 in the article text--> and 28 years.<ref name=NIHStat/> This is primarily because of its association with heart disease,<ref name=Kritharides2017>{{cite journal |vauthors=Kritharides L, Chow V, Lambert TJ |date=6 February 2017 |title=Cardiovascular disease in patients with schizophrenia |journal=The Medical Journal of Australia |volume=206 |issue=2 |pages=91–95 |doi=10.5694/mja16.00650 |pmid=28152356 |s2cid=5388097}}</ref> diabetes,<ref name=NIHStat/> ], poor diet, a ], and smoking, with an increased rate of suicide playing a lesser role.<ref name=Laursen2014/><ref>{{cite journal | vauthors = Erlangsen A, Eaton WW, Mortensen PB, Conwell Y | title = Schizophrenia—a predictor of suicide during the second half of life? | journal = Schizophrenia Research | volume = 134 | issue = 2–3 | pages = 111–117 | date = February 2012 | pmid = 22018943 | pmc = 3266451 | doi = 10.1016/j.schres.2011.09.032 }}</ref> Side effects of antipsychotics may also increase the risk.<ref name=Laursen2014/>


Almost 40% of those with schizophrenia die from complications of cardiovascular disease which is seen to be increasingly associated.<ref name=Rastogi2020/> An underlying factor of sudden cardiac death may be ] (BrS) – BrS mutations that overlap with those linked with schizophrenia are the ] mutations.<ref name=Rastogi2020/> BrS may also be drug-induced from certain antipsychotics and antidepressants.<ref name=Rastogi2020/> ], or excessive fluid intake, is relatively common in people with chronic schizophrenia.<ref>{{cite book| vauthors = Goroll AH, Mulley AG |title=Primary Care Medicine: Office Evaluation and Management of The Adult Patient |edition=Sixth|date=2011|publisher=Lippincott Williams & Wilkins|isbn=978-1-4511-2159-9|page=Chapter 101|url=https://books.google.com/books?id=fXpKo1afC2YC&pg=PT1766}}</ref><ref name=Rizvi2019>{{cite journal | vauthors = Rizvi S, Gold J, Khan AM | title = Role of Naltrexone in Improving Compulsive Drinking in Psychogenic Polydipsia. | journal = Cureus | date = 5 August 2019 | volume = 11 | issue = 8 | page =e5320 | doi = 10.7759/cureus.5320 | doi-access = free | pmid = 31598428| pmc = 6777931 }}</ref> This may lead to ] which can be life-threatening. Antipsychotics can lead to a ], but there are several other factors that may contribute to the disorder; it may reduce life expectancy by 13 percent.<ref name=Rizvi2019/> Barriers to improving the mortality rate in schizophrenia are poverty, overlooking the symptoms of other illnesses, stress, stigma, and medication side effects.<ref>{{cite journal |vauthors=Seeman MV |s2cid=170078453 |title=Schizophrenia Mortality: Barriers to Progress |journal=The Psychiatric Quarterly |volume=90 |issue=3 |pages=553–563 |date=September 2019 |pmid=31147816 |doi=10.1007/s11126-019-09645-0}}</ref>
One retrospective study has shown that about a third of people make a full recovery, about a third show improvement but not a full recovery, and a third remain ill.<ref name="fn_42"> The Vermont longitudinal study of persons with severe mental illness, II: Long-term outcome of subjects who retrospectively met DSM-III criteria for schizophrenia. ''American Journal of Psychiatry'', 144(6), 727&ndash;35.<br></ref> A more recent study using stricter recovery criteria (i.e. concurrent remission of positive and negative symptoms and specific instances of adequate social / vocational functioning) reported a recovery rate of 13.7%.<ref name="fn_43"> Symptomatic and functional recovery from a first episode of schizophrenia or schizoaffective disorder. ''American Journal of Psychiatry'', 161, 473-479.<br></ref>


<!-- Disability -->
The exact definition of what constitutes a recovery has not been widely defined, however, although criteria have recently been suggested to define a remission in symptoms.<ref name="fn_63" /> Therefore, this makes it difficult to give an exact estimate as recovery and remission rates are not always comparable across studies.
Schizophrenia is a major cause of ]. In 2016, it was classed as the 12th most disabling condition.<ref>{{cite journal | vauthors = Charlson FJ, Ferrari AJ, Santomauro DF, Diminic S, Stockings E, Scott JG, McGrath JJ, Whiteford HA | title = Global Epidemiology and Burden of Schizophrenia: Findings From the Global Burden of Disease Study 2016 | journal = Schizophrenia Bulletin | volume = 44 | issue = 6 | pages = 1195–1203 | date = October 2018 | pmid = 29762765 | pmc = 6192504 | doi = 10.1093/schbul/sby058 }}</ref> Approximately 75% of people with schizophrenia have ongoing disability with relapses.<ref>{{cite journal | vauthors = Smith T, Weston C, Lieberman J | title = Schizophrenia (maintenance treatment) | journal = American Family Physician | volume = 82 | issue = 4 | pages = 338–339 | date = August 2010 | pmid = 20704164}}</ref> Some people do recover completely and others function well in society.<ref>{{cite journal | vauthors = Warner R | s2cid = 26666000 | title = Recovery from schizophrenia and the recovery model | journal = Current Opinion in Psychiatry | volume = 22 | issue = 4 | pages = 374–380 | date = July 2009 | pmid = 19417668 | doi = 10.1097/YCO.0b013e32832c920b }}</ref> Most people with schizophrenia live independently with community support.<ref name=Lancet2009/> About 85% are unemployed.<ref name=Lancet2016/> In people with a first episode of psychosis in schizophrenia a good long-term outcome occurs in 31%, an intermediate outcome in 42% and a poor outcome in 31%.<ref>{{cite journal | vauthors = Menezes NM, Arenovich T, Zipursky RB | s2cid = 23475454 | title = A systematic review of longitudinal outcome studies of first-episode psychosis | journal = Psychological Medicine | volume = 36 | issue = 10 | pages = 1349–62 | date = October 2006 | pmid = 16756689 | doi = 10.1017/S0033291706007951 | url = https://pdfs.semanticscholar.org/8539/923c1b4f6bacb128d478b9ec7f6e95559210.pdf | archive-url = https://web.archive.org/web/20200922015257/https://pdfs.semanticscholar.org/8539/923c1b4f6bacb128d478b9ec7f6e95559210.pdf | archive-date = 22 September 2020}}</ref> Males are affected more often than females, and have a worse outcome.<ref>{{cite book |vauthors=Coyle JT |title=Neurodegenerative Diseases |chapter=Schizophrenia: Basic and Clinical |series=Advances in Neurobiology |volume=15 |pages=255–280 |date=2017 |pmid=28674984 |doi=10.1007/978-3-319-57193-5_9|isbn=978-3-319-57191-1 }}</ref> Studies showing that outcomes for schizophrenia appear better in the ] than the ]<ref name=Isa07>{{cite journal | vauthors = Isaac M, Chand P, Murthy P | title = Schizophrenia outcome measures in the wider international community | journal = The British Journal of Psychiatry. Supplement | volume = 50 | pages = s71–77 | date = August 2007 | pmid = 18019048 | doi = 10.1192/bjp.191.50.s71 | doi-access = free }}</ref> have been questioned.<ref>{{cite journal | vauthors = Cohen A, Patel V, Thara R, Gureje O | title = Questioning an axiom: better prognosis for schizophrenia in the developing world? | journal = Schizophrenia Bulletin | volume = 34 | issue = 2 | pages = 229–244 | date = March 2008 | pmid = 17905787 | pmc = 2632419 | doi = 10.1093/schbul/sbm105 }}</ref> Social problems, such as long-term unemployment, poverty, homelessness, exploitation, ] and victimization are common consequences, and lead to ].<ref name=Killaspy2014/><ref name=Charleson2018/>


<!-- Suicide -->
The ] conducted two long-term follow-up studies involving more than 2,000 people suffering from schizophrenia in different countries. These studies findings were that these patients have much better long-term outcomes in poor countries (], ] and ]) than in rich countries (], ], ], ], ], ], ], and ]),<ref name="fn_44"> Revisiting the developed versus developing country distinction in course and outcome in schizophrenia: results from ISoS, the WHO collaborative followup project. International Study of Schizophrenia. ''Schizophrenia Bulletin'', 26 (4), 835-46.<br></ref> despite the fact antipsychotic drugs are typically not widely available in poorer countries, thus raising questions about the effectiveness such drug-based treatments.
There is a higher than average ] associated with schizophrenia estimated at 5% to 6%, most often occurring in the period following onset or first hospital admission.<ref name=Ferri2019>{{cite book |title=Ferri's clinical advisor 2019: 5 books in 1 |pages=1225–1226|date=2019 |isbn=9780323530422 | vauthors = Ferri FF |publisher=Elsevier }}</ref><ref name=Jop2010/> Several times more (20 to 40%) attempt suicide at least once.<ref name=DSM5/><ref name=Chiang2016/> There are a variety of risk factors, including male sex, depression, a high ],<ref>{{cite journal | vauthors = Carlborg A, Winnerbäck K, Jönsson EG, Jokinen J, Nordström P | s2cid = 204385719 | title = Suicide in schizophrenia | journal = Expert Review of Neurotherapeutics | volume = 10 | issue = 7 | pages = 1153–1164 | date = July 2010 | pmid = 20586695 | doi = 10.1586/ern.10.82 | doi-access = free }}</ref> heavy smoking,<ref>{{cite journal |vauthors=Tsoi DT, Porwal M, Webster AC |title=Interventions for smoking cessation and reduction in individuals with schizophrenia |journal=The Cochrane Database of Systematic Reviews |issue=2 |page=CD007253 |date=28 February 2013 |volume=2013 |pmid=23450574|doi=10.1002/14651858.CD007253.pub3|pmc=6486303 }}</ref> and substance use.<ref name=Khokhar2018/> Repeated relapse is linked to an increased risk of suicidal behavior.<ref name=Taylor2019/> The use of clozapine can reduce the risk of suicide, and of aggression.<ref>{{cite journal |vauthors=Sriretnakumar V, Huang E, Müller DJ |date=2015 |title=Pharmacogenetics of clozapine treatment response and side-effects in schizophrenia: an update |journal=Expert Opinion on Drug Metabolism & Toxicology |volume=11 |issue=11 |pages=1709–1731 |doi=10.1517/17425255.2015.1075003 |pmid=26364648 |s2cid=207492339}}</ref>


<!-- Drug use -->
Prognosis also depends on some other factors. Females tend to show recovery rates higher than males, and acute and sudden onset of schizophrenia is associated with higher rates of recovery, while gradual onset is associated with lower rates. Most studies done on this subject, however, are correlational in nature, and a clear cause-and-effect relationship is difficult to establish. Pre-morbid functioning and positive prognosis also seem to be correlated.
A strong association between ] has been shown in worldwide studies.<ref>{{cite journal | vauthors = de Leon J, Diaz FJ | s2cid = 32975940 | title = A meta-analysis of worldwide studies demonstrates an association between schizophrenia and tobacco smoking behaviors | journal = Schizophrenia Research | volume = 76 | issue = 2–3 | pages = 135–157 | date = July 2005 | pmid = 15949648 | doi = 10.1016/j.schres.2005.02.010 }}</ref><ref name=Keltner2006>{{cite journal | vauthors = Keltner NL, Grant JS | title = Smoke, smoke, smoke that cigarette | journal = Perspectives in Psychiatric Care | volume = 42 | issue = 4 | pages = 256–261 | date = November 2006 | pmid = 17107571 | doi = 10.1111/j.1744-6163.2006.00085.x }}</ref> ] is especially high in those diagnosed with schizophrenia, with estimates ranging from 80 to 90% being regular smokers, as compared to 20% of the general population.<ref name=Keltner2006/> Those who smoke tend to smoke heavily, and additionally smoke cigarettes with high nicotine content.<ref name=DSMIV/> Some propose that this is in an effort to improve symptoms.<ref>{{cite journal | vauthors = Kumari V, Postma P | s2cid = 15581894 | title = Nicotine use in schizophrenia: the self medication hypotheses | journal = Neuroscience and Biobehavioral Reviews | volume = 29 | issue = 6 | pages = 1021–1034 | date = January 2005 | pmid = 15964073 | doi = 10.1016/j.neubiorev.2005.02.006 }}</ref> Among people with schizophrenia use of cannabis is also common.<ref name=Khokhar2018/>


Schizophrenia leads to an increased risk of dementia.<ref>{{cite journal |vauthors=Cai L, Huang J |title=Schizophrenia and risk of dementia: a meta-analysis study |journal=Neuropsychiatr Dis Treat |volume=14 |issue= |pages=2047–2055 |date=2018 |pmid=30147318 |pmc=6095111 |doi=10.2147/NDT.S172933 |doi-access=free }}</ref>
In a study of over 168,000 Swedish citizens undergoing psychiatric treatment, schizophrenia was associated with an average life expectancy of approximately 80-85% of that of the general population. Women with a diagnosis of schizophrenia were found to have a slightly better life expectancy than that of men, and as a whole, a diagnosis of schizophrenia was associated with a better life expectancy than ], ], ] and ].<ref name="fn_45"> Life expectancies for individuals with psychiatric diagnoses. ''Public Health'', 115 (5), 328-37.<br></ref>


===Violence===
There is an extremely high ] rate associated with schizophrenia. A recent study showed that 30% of patients diagnosed with this condition had attempted suicide at least once during their lifetime.<ref name="fn_46"> Suicidal behavior in patients with schizophrenia and other psychotic disorders. ''American Journal of Psychiatry'', 156(10), 1590&ndash;5.<br></ref> Another study suggested that 10% of persons with schizophrenia die by suicide.<ref name="fn_47"> Schizophrenics kill themselves too: a review of risk factors for suicide. ''Schizophrenia Bulletin'', 16(4), 571&ndash;89.<br></ref>
Most people with schizophrenia are not aggressive, and are more likely to be victims of violence rather than perpetrators.<ref name=DSM5/> People with schizophrenia are commonly exploited and victimized by violent crime as part of a broader dynamic of social exclusion.<ref name=Killaspy2014/><ref name=Charleson2018/> People diagnosed with schizophrenia are also subject to forced drug injections, seclusion, and restraint at high rates.<ref name=BeckerKilian2006/><ref name=Capdevielle2009/>


The risk of violence by people with schizophrenia is small. There are minor subgroups where the risk is high.<ref name=Richard-Devantoy2009>{{cite journal |vauthors=Richard-Devantoy S, Olie JP, Gourevitch R |title= |journal=L'Encephale |volume=35 |issue=6 |pages=521–530 |date=December 2009 |pmid=20004282 |doi=10.1016/j.encep.2008.10.009}}</ref> This risk is usually associated with a comorbid disorder such as a substance use disorder – in particular alcohol, or with antisocial personality disorder.<ref name=Richard-Devantoy2009/> Substance use disorder is strongly linked, and other risk factors are linked to deficits in cognition and social cognition including facial perception and insight that are in part included in ] impairments.<ref>{{cite journal |vauthors=Ng R, Fish S, Granholm E |title=Insight and theory of mind in schizophrenia. |journal=Psychiatry Research |volume=225 |issue=1–2 |pages=169–174 |date=30 January 2015 |pmid=25467703 |doi=10.1016/j.psychres.2014.11.010|pmc=4269286 }}</ref><ref>{{cite journal |vauthors=Bora E |title=Relationship between insight and theory of mind in schizophrenia: A meta-analysis |journal=Schizophrenia Research |volume=190 |pages=11–17 |date=December 2017 |pmid=28302393 |doi=10.1016/j.schres.2017.03.029|s2cid=36263370 }}</ref> Poor cognitive functioning, decision-making, and facial perception may contribute to making a wrong judgement of a situation that could result in an inappropriate response such as violence.<ref>{{cite journal |vauthors=Darmedru C, Demily C, Franck N |title= |journal=L'Encephale |volume=44 |issue=2 |pages=158–167 |date=April 2018 |pmid=28641817 |doi=10.1016/j.encep.2017.05.001}}</ref> These associated risk factors are also present in antisocial personality disorder which when present as a comorbid disorder greatly increases the risk of violence.<ref>{{cite journal | vauthors = Richard-Devantoy S, Bouyer-Richard AI, Jollant F, Mondoloni A, Voyer M, Senon JL | title = | journal = Revue d'Épidemiologie et de Santé Publique | volume = 61 | issue = 4 | pages = 339–350 | date = August 2013 | pmid = 23816066 | doi = 10.1016/j.respe.2013.01.096 }}</ref><ref>{{cite journal | vauthors = Sedgwick O, Young S, Baumeister D, Greer B, Das M, Kumari V | title = Neuropsychology and emotion processing in violent individuals with antisocial personality disorder or schizophrenia: The same or different? A systematic review and meta-analysis | journal = The Australian and New Zealand Journal of Psychiatry | volume = 51 | issue = 12 | pages = 1178–1197 | date = December 2017 | pmid = 28992741 | doi = 10.1177/0004867417731525 | s2cid = 206401875 | doi-access = free }}</ref>
== Recovery and Rehabilitation ==


==Epidemiology==
Just as the diagnosis itself is mired in controversy and counter-accusation, it is difficult to establish a clear picture of recovery and rehabilitation. Both long ago and in the recent past, patients in developed countries were told that chances of recovery were limited, with statistics being quoted to support this negative prognosis. Today, with the advent of a vocal ] in mental health, statistics are quoted in a conflicting fashion, and attention is drawn to cultural and local factors in impeding or accelerating recovery. Rehabilitation provision is uneven and strongly dependent on local political culture and/or resources.
{{Main|Epidemiology of schizophrenia}}
[[File:Schizophrenia world map-Deaths per million persons-WHO2012.svg|thumb|upright=1.3|Deaths per million persons due to schizophrenia in 2012
{{Div col|small=yes|colwidth=10em}}
{{legend|#ffff20|0–0}}{{legend|#ffc020|1–1}}{{legend|#ff9a20|2–2}}{{legend|#f08015|3–3}}{{legend|#d85010|4–6}}{{legend|#d02010|7–20}}{{div col end}}]]
In 2017,{{update after|2022|8|22}} the ] estimated there were 1.1&nbsp;million new cases;<ref name=GBD2018/> in 2022 the World Health Organization (WHO) reported a total of 24 million cases globally.<ref name=WHO2022/> Schizophrenia affects around 0.3–0.7% of people at some point in their life.<ref name=Javitt2014/><ref name=NIHStat>{{cite web|title=Schizophrenia |url= http://www.nimh.nih.gov/health/statistics/prevalence/schizophrenia.shtml |date= 22 April 2022 |access-date= 23 August 2022 |publisher= US ] (NIMH)|work= Statistics}}</ref> In areas of conflict this figure can rise to between 4.0 and 6.5%.<ref>{{cite journal | vauthors = Charlson F, van Ommeren M, Flaxman A, Cornett J, Whiteford H, Saxena S | title = New WHO prevalence estimates of mental disorders in conflict settings: a systematic review and meta-analysis | journal = Lancet | volume = 394 | issue = 10194 | pages = 240–248 | date = July 2019 | pmid = 31200992 | pmc = 6657025 | doi = 10.1016/S0140-6736(19)30934-1 }}</ref> It occurs 1.4&nbsp;times more frequently in males than females and typically appears earlier in men.<ref name=BMJ07/>


Worldwide, schizophrenia is the most common ].<ref name=Kar2016/> The frequency of schizophrenia varies across the world,<ref name=DSM5/> within countries,<ref>{{cite journal | vauthors = Kirkbride JB, Fearon P, Morgan C, Dazzan P, Morgan K, Tarrant J, Lloyd T, Holloway J, Hutchinson G, Leff JP, Mallett RM, Harrison GL, Murray RM, Jones PB | title = Heterogeneity in incidence rates of schizophrenia and other psychotic syndromes: findings from the 3-center AeSOP study | journal = Archives of General Psychiatry | volume = 63 | issue = 3 | pages = 250–258 | date = March 2006 | pmid = 16520429 | doi = 10.1001/archpsyc.63.3.250 | doi-access = free }}</ref> and at the local and neighborhood level;<ref>{{cite journal | vauthors = Kirkbride JB, Fearon P, Morgan C, Dazzan P, Morgan K, Murray RM, Jones PB | title = Neighbourhood variation in the incidence of psychotic disorders in Southeast London | journal = Social Psychiatry and Psychiatric Epidemiology | volume = 42 | issue = 6 | pages = 438–445 | date = June 2007 | pmid = 17473901 | doi = 10.1007/s00127-007-0193-0 | s2cid = 19655724 }}</ref> this variation in ] between studies over time, across geographical locations, and by gender is as high as fivefold.<ref name=Lancet2016/>
==Schizophrenia and drug use==
The relationship between schizophrenia and drug use is complex, meaning that a clear causal connection between drug use and schizophrenia has been difficult to tease apart. There is strong evidence that using certain drugs can trigger either the onset or relapse of schizophrenia in some people. It may also be the case, however, that people with schizophrenia use drugs to overcome negative feelings associated with both the commonly prescribed antipsychotic medication and the condition itself, where negative emotion, ] and ] are all considered to be core features.


Schizophrenia causes approximately one percent of worldwide ]{{update after|2022|8|24}}<ref name=BMJ07/> and resulted in 17,000 deaths in 2015.<ref name=GBD2015/>
The rate of substance use is known to be particularly high in this group. In a recent study, 60% of people with schizophrenia were found to use substances and 37% would be diagnosable with a substance use disorder.<ref name="fn_74"> Substance use in persons with schizophrenia: baseline prevalence and correlates from the NIMH CATIE study. ''Journal of Nervous and Mental Disease'', 194(3), 164-72.<br></ref>


In 2000,{{update after|2022|8|22}} WHO found the percentage of people affected and the number of new cases that develop each year is roughly similar around the world, with age-standardized prevalence per 100,000 ranging from 343 in Africa to 544 in Japan and Oceania for men, and from 378 in Africa to 527 in Southeastern Europe for women.<ref>{{update after|2022|8|22}} {{cite web|title=Global burden of schizophrenia in the year 2000|date= 15 August 2006| url=https://www.who.int/healthinfo/statistics/bod_schizophrenia.pdf|publisher=] | vauthors = Ayuso-Mateos JL |access-date=27 February 2013|url-status=live|archive-url=https://web.archive.org/web/20160304075113/http://www.who.int/healthinfo/statistics/bod_schizophrenia.pdf|archive-date=4 March 2016}}</ref>
===Amphetamines===


==History==
As amphetamines are believed to elevate dopamine production, and that an excess of dopamine is responsible for schizophrenia (known as the ]) the amphetamines may worsen schizophrenia symptoms.
{{Main|History of schizophrenia}}

===Hallucinogens===
Schizophrenia can sometimes be triggered by heavy use of ] drugs, although some claim that a predisposition towards developing schizophrenia is needed for this to occur. There is also some evidence suggesting that people suffering schizophrenia but responding to treatment can have relapse because of subsequent drug use. Some widely known cases where hallucinogens have been suspected of precipitating schizophrenia are ] founder-member ] and ] songwriter ].

Drugs such as ], ], and ] have been used to mimic schizophrenia for research purposes, although this has now fallen out of favor with the ], as the differences between the drug induced states and the typical presentation of schizophrenia have become clear.

Hallucinogenic drugs were also briefly tested as possible treatments for schizophrenia by psychiatrists such as ] and ] in the 1950s. It was mainly for this experimental treatment of schizophrenia that LSD administration was legal, briefly before its use as a ] led to its criminalization.

===Cannabis===
There is evidence that ] use can contribute to schizophrenia. Some studies suggest that cannabis is neither a ] factor in developing schizophrenia, but that cannabis may significantly increase the risk of developing schizophrenia and may be, among other things, a significant causal factor. Nevertheless, some previous research in this area has been criticised as it has often not been clear whether cannabis use is a cause or effect of schizophrenia. To address this issue, a recent review of studies from which a causal contribution to schizophrenia can be assessed has suggested that cannabis statistically doubles the risk of developing schizophrenia on the individual level, and may, assuming a causal relationship, be responsible for up to 8% of cases in the population.<ref name="fn_48"> Causal association between cannabis and psychosis: examination of the evidence. ''British Journal of Psychiatry'', 184, 110-7. ()<br></ref>

===Tobacco===
It has been noted that the majority of people with schizophrenia (estimated between 75% and 90%) smoke ]. However, people diagnosed with schizophrenia have a much lower than average chance of developing and dying from ]. While the reason for this is unknown, it may be because of a genetic resistance to the cancer, a side-effect of drugs being taken, or a statistical effect of increased likelihood of dying from causes other than lung cancer.<ref name="fn_49" />

It is argued that the increased level of smoking in schizophrenia may be due to a desire to self-medicate with ]. A recent study of over 50,000 ] conscripts found that there was a small but ] protective effect of smoking cigarettes on the risk of developing schizophrenia later in life.<ref name="fn_50"> Investigating the association between cigarette smoking and schizophrenia in a cohort study. ''American Journal of Psychiatry'', 160 (12), 2216&ndash;21.<br></ref> While the authors of the study stressed that the risks of smoking far outweigh these minor benefits, this study provides further evidence for the 'self-medication' theory of smoking in schizophrenia and may give clues as to how schizophrenia might develop at the molecular level. Furthermore, many people with schizophrenia have smoked tobacco products long before they are diagnosed with the illness, and some groups advocate that the chemicals in tobacco have actually contributed to the onset of the illness and have no benefit of any kind.

It is of interest that cigarette smoking affects liver function such that the ] used to treat schizophrenia are broken down in the blood stream more quickly. This means that smokers with schizophrenia need slightly higher doses of antipsychotic drugs in order for them to be effective than do their non-smoking counterparts.

==Schizophrenia and violence==
===Violence perpetrated by people with schizophrenia===
Although schizophrenia is sometimes associated with violence in the media only a small minority of people with schizophrenia become violent, and only a minority of people who commit criminal violence have been diagnosed with schizophrenia.

Research has suggested that schizophrenia is associated with a slight increase in risk of violence, although this risk is largely due to a small sub-group of individuals for whom violence is associated with concurrent substance abuse and ceasing psychiatric drugs.<ref name="fn_51"> Predicting violence in schizophrenia: a prospective study. ''Schizophrenia Research'', 67(2-3), 247-52. <br></ref> For the most serious acts of violence, long-term independent studies of convicted murderers in both ]<ref name="fn_52"> Homicide and mental illness in New Zealand, 1970-2000. ''British Journal of Psychiatry'', 185, 394-8.<br></ref> and ]<ref name="fn_53"> Psychiatric morbidity among homicide offenders: a Swedish population study. ''American Journal of Psychiatry'', 161(11), 2129-31.<br></ref> found that 3.7%&ndash;8.9% had been given a previous diagnosis of schizophrenia.

There is some evidence to suggest that in some people, the drugs used to treat schizophrenia may produce an increased risk for violence, largely due to agitation induced by ], a ] sometimes associated with ] medication.<ref name="fn_54"> Neuroleptic-induced akathisia and violence: a review. ''Journal of Forensic Science'', 48<br></ref> Similarly, abuse experienced in childhood may contribute both to a slight increase in risk for violence in adulthood, as well as the development of schizophrenia.<ref name="fn_16" />

===Violence against people with schizophrenia===
Research has shown that a person diagnosed with schizophrenia is more likely to be a victim of violence (4.3% in a one month period) than the perpetrator.<ref name="fn_55"> Victimization of patients with schizophrenia and related disorders. ''Australia and New Zealand Journal of Psychiatry'', 39(3), 169-74. (1), 187-9.<br></ref>


===Conceptual development===
==Alternative approaches to schizophrenia==
{{Main|History of schizophrenia#Conceptual development}}
An approach broadly known as the ] movement, notably most active in the 1960s, has opposed the orthodox medical view of schizophrenia as an illness.
{{Further|Dementia praecox}}
].]]
Accounts of a schizophrenia-like ] are rare in records before the 19th century; the earliest case reports were in 1797 and 1809.<ref>{{cite journal | vauthors = Heinrichs RW | title = Historical origins of schizophrenia: two early madmen and their illness | journal = Journal of the History of the Behavioral Sciences | volume = 39 | issue = 4 | pages = 349–363 | year = 2003 | pmid = 14601041 | doi = 10.1002/jhbs.10152 | doi-access = free }}</ref> The term '']'' ("premature dementia") was used by German psychiatrist Heinrich Schüle in 1886 and then in 1891 by ] in a case report of ]. In 1893 ] used the term in making a distinction, known as the ], between the two psychoses: dementia praecox and ] (now called ]).<ref name=Laursen2014/> When it became evident that the disorder was not a degenerative dementia, it was renamed ''schizophrenia'' by ] in 1908.<ref name=Kuhn2004>{{cite journal | vauthors = Kuhn R, Cahn CH | title = Eugen Bleuler's concepts of psychopathology | journal = History of Psychiatry | volume = 15 | issue = 59 Pt 3 | pages = 361–366 | date = September 2004 | pmid = 15386868 | doi = 10.1177/0957154X04044603 | s2cid = 5317716 }}</ref>


The word ''schizophrenia'' ("splitting of the mind") is ], derived from the ] ''schizein'' ({{Langx|grc|σχίζειν|lit=to split}}) and ''phrēn'' ({{langx|grc|φρήν|lit=mind}}).<ref>{{cite web |title=Schizophrenia {{!}} Definition of Schizophrenia by Lexico |url=https://www.lexico.com/en/definition/schizophrenia |archive-url=https://web.archive.org/web/20200310144713/https://www.lexico.com/en/definition/schizophrenia |archive-date=10 March 2020 |publisher=Lexico Dictionaries {{!}} English }}</ref> Its use was intended to describe the separation of function between ], ], memory, and perception.<ref name=Kuhn2004/>
Psychiatrist ] argues that psychiatric patients are not ill but are just individuals with unconventional thoughts and behavior that make society uncomfortable. He argues that society unjustly seeks to control such individuals by classifying their behavior as an illness and forcibly treating them as a method of ]. It is worth noting that Szasz has never considered himself to be "anti-psychiatry" in the sense of being against psychiatric treatment, but simply believes that it should be conducted between consenting adults, rather than imposed upon anyone against his or her will. Szasz co-founded the anti-psychiatry group ] with the ], who are well-noted for their anti-psychiatric stance.


In the early 20th century, the psychiatrist ] categorized the psychotic symptoms of schizophrenia into two groups: hallucinations and delusions. The hallucinations were listed as specific to auditory and the delusions included thought disorders. These were seen as important symptoms, termed ]. The most common first-rank symptom was found to belong to thought disorders.{{page needed|date=August 2022}}<ref>{{page needed|date=August 2022}} {{cite book| vauthors = Schneider K |author-link1=Kurt Schneider |title=Clinical Psychopathology |edition=5th |year=1959 |publisher=Grune & Stratton |location=New York }}</ref>{{page needed|date=August 2022}}<ref>{{page needed|date=August 2022}} {{cite book | vauthors = Moore D |title=Textbook of Clinical Neuropsychiatry |edition=Second |publisher=CRC Press |date=25 April 2008|isbn=9781444109740 }}</ref> In 2013 the first-rank symptoms were excluded from the DSM-5 criteria;<ref>{{cite journal | vauthors = Tandon R, Gaebel W, Barch DM, Bustillo J, Gur RE, Heckers S, Malaspina D, Owen MJ, Schultz S, Tsuang M, Van Os J, Carpenter W | title = Definition and description of schizophrenia in the DSM-5 | journal = Schizophrenia Research | volume = 150 | issue = 1 | pages = 3–10 | date = October 2013 | pmid = 23800613 | doi = 10.1016/j.schres.2013.05.028 | s2cid = 17314600 }}</ref> while they may not be useful in diagnosing schizophrenia, they can assist in ].<ref>{{cite journal | vauthors = Picardi A | title = The Two Faces of First-Rank Symptoms | journal = Psychopathology | volume = 52 | issue = 4 | pages = 221–231 | date = 2019 | pmid = 31610542 | doi = 10.1159/000503152 | s2cid = 204702486 | doi-access = free }}</ref>
Similarly, psychiatrists ], ], ] and other mental health professionals have argued that the symptoms of what is normally called mental illness are comprehensible reactions to impossible demands that society and particularly family life places on some sensitive individuals. Laing, Arieti and Lidz were revolutionary in valuing the ''content'' of ] experience as worthy of interpretation, rather than considering it simply as a secondary but essentially meaningless marker of underlying psychological or neurological distress. Laing's work, co-authored with Aaron Esterson, ''Sanity, Madness and the Family'' (1964) described eleven case studies of people diagnosed with schizophrenia and argued that the content of their actions and statements was meaningful and logical in the context of their family and life situations. Arieti's '']'' won the 1975 scientific ] in the United States. In the books ''Schizophrenia and the Family'' and ''The Origin and Treatment of Schizophrenic Disorders'' Lidz and his colleagues explain their belief that parental behaviour can result in mental illness in children.


Subtypes of schizophrenia—classified as paranoid, disorganized, ], undifferentiated, and residual—were difficult to distinguish and are no longer recognized as separate conditions by DSM-5 (2013) or ICD-11.<ref name=Reed2019>{{cite journal | vauthors = Reed GM, First MB, Kogan CS, Hyman SE, Gureje O, Gaebel W, Maj M, Stein DJ, Maercker A, Tyrer P, Claudino A, Garralda E, Salvador-Carulla L, Ray R, Saunders JB, Dua T, Poznyak V, Medina-Mora ME, Pike KM, Ayuso-Mateos JL, Kanba S, Keeley JW, Khoury B, Krasnov VN, Kulygina M, Lovell AM, de Jesus Mari J, Maruta T, Matsumoto C, Rebello TJ, Roberts MC, Robles R, Sharan P, Zhao M, Jablensky A, Udomratn P, Rahimi-Movaghar A, Rydelius PA, Bährer-Kohler S, Watts AD, Saxena S | title = Innovations and changes in the ICD-11 classification of mental, behavioural and neurodevelopmental disorders | journal = World Psychiatry | volume = 18 | issue = 1 | pages = 3–19 | date = February 2019 | pmid = 30600616 | pmc = 6313247 | doi = 10.1002/wps.20611 }}</ref><ref>{{Cite web |title=Updates to DSM-5 Criteria & Text |url=https://www.psychiatry.org/psychiatrists/practice/dsm/updates-to-dsm-5/updates-to-dsm-5-criteria-text |access-date=21 February 2019 |publisher=www.psychiatry.org}}</ref><ref>{{cite journal | vauthors = Tandon R | title = Schizophrenia and Other Psychotic Disorders in Diagnostic and Statistical Manual of Mental Disorders (DSM)-5: Clinical Implications of Revisions from DSM-IV | journal = Indian Journal of Psychological Medicine | volume = 36 | issue = 3 | pages = 223–225 | date = July 2014 | pmid = 25035542 | pmc = 4100404 | doi = 10.4103/0253-7176.135365 | doi-access = free }}</ref>
In the 1976 book '']'', psychologist ] proposed that until the beginning of historic times, schizophrenia or a similar condition was the normal state of human consciousness. This would take the form of a "]" where a normal state of low affect, suitable for routine activities, would be interrupted in moments of crisis by "mysterious voices" giving instructions, which early people characterized as interventions from the gods. This theory was briefly controversial. Continuing research has failed to either further confirm or refute the thesis.


=== Breadth of diagnosis ===
Psychiatrist ] has argued that schizophrenia may be the evolutionary price we pay for a left brain hemisphere specialization for ].<ref name="fn_56"> Schizophrenia as failure of hemispheric dominance for language. ''Trends in Neurosciences'', 20(8), 339&ndash;343.<br></ref> Since psychosis is associated with greater levels of right brain hemisphere activation and a reduction in the usual left brain hemisphere dominance, our language abilities may have evolved at the cost of causing schizophrenia when this system breaks down.
Before the 1960s, nonviolent ]s and women were sometimes diagnosed with schizophrenia, categorizing the latter as ill for not performing their duties as wives and mothers.<ref name= Lane2010/> In the mid- to late 1960s, black men were categorized as "hostile and aggressive" and diagnosed as schizophrenic at much higher rates, their ] and ] activism labeled as delusions.<ref name=Lane2010>{{Cite web |vauthors= Lane C |date= 5 May 2010|title=How Schizophrenia Became a Black Disease: An Interview With Jonathan Metzl|url=http://www.psychologytoday.com/blog/side-effects/201005/how-schizophrenia-became-black-disease-interview-jonathan-metzl|access-date=5 April 2021|work=]}}</ref><ref>{{page needed|date=August 2022}} {{Cite book|vauthors=Metz J|title=]|year=2010|isbn=978-0-8070-8592-9| publisher = Beacon Press}}</ref>


In the early 1970s in the United States, the diagnostic model for schizophrenia was broad and clinically based using ]. Schizophrenia was diagnosed far more in the United States than in Europe, where the ] criteria were followed. The US model was criticised for failing to demarcate clearly those people with a mental illness. In 1980 DSM III was published and showed a shift in focus from the clinically based ] to a reason-based medical model.{{what|date=December 2024}}<ref>{{cite journal |vauthors=Wilson M |date=March 1993 |title=DSM-III and the transformation of American psychiatry: a history |journal=The American Journal of Psychiatry |volume=150 |issue=3 |pages=399–410 |doi=10.1176/ajp.150.3.399 |pmid=8434655}}</ref> DSM IV brought an increased focus on an evidence-based medical model.<ref>{{cite journal |vauthors=Fischer BA |date=December 2012 |title=A review of American psychiatry through its diagnoses: the history and development of the Diagnostic and Statistical Manual of Mental Disorders. |journal=The Journal of Nervous and Mental Disease |volume=200 |issue=12 |pages=1022–1030 |doi=10.1097/NMD.0b013e318275cf19 |pmid=23197117 |s2cid=41939669}}</ref>
Researchers into ] have speculated that in some cultures schizophrenia or related conditions may predispose an individual to becoming a shaman<ref name="fn_57"> How shamanism and group selection may reveal the origins of schizophrenia. ''Medical Hypothesis'', 58(3), 244&ndash;8.<br></ref>. Certainly, the experience of having access to multiple realities is not uncommon in schizophrenia, and is a core experience in many shamanic traditions. Equally, the shaman may have the skill to bring on and direct some of the ] psychiatrists label as illness. Speculations regarding primary and important religious figures as having schizophrenia abound. Some commentators have endorsed the idea that major religious figures experienced psychosis, heard voices and displayed delusions of grandeur.


=== Historical treatment ===
] tends to hold the view that schizophrenia is primarily caused by imbalances in the body's reserves and absorption of ]s, ]s, fats, and/or the presence of excessive levels of toxic ]. The body's adverse reactions to ] are also strongly implicated in some alternative theories (see ]).
{{Main|History of schizophrenia#Development of treatments in the 20th century}}
], the first antipsychotic developed in the 1950s]]
In the 1930s a number of shock procedures which induced seizures (convulsions) or comas were used to treat schizophrenia.<ref name=Jones2000>{{cite journal |vauthors=Jones K |date=March 2000 |title=Insulin coma therapy in schizophrenia |journal=Journal of the Royal Society of Medicine |volume=93 |issue=3 |pages=147–149 |doi=10.1177/014107680009300313 |pmc=1297956 |pmid=10741319}}</ref> ] involved injecting large doses of ] to induce comas, which in turn produced ] and convulsions.<ref name=Jones2000/><ref>{{cite journal |vauthors=Jobes DA, Chalker SA |date=26 September 2019 |title=One Size Does Not Fit All: A Comprehensive Clinical Approach to Reducing Suicidal Ideation, Attempts, and Deaths. |journal=International Journal of Environmental Research and Public Health |volume=16 |issue=19 |page=3606 |doi=10.3390/ijerph16193606 |pmc=6801408 |pmid=31561488 |doi-access=free}}</ref> The use of electricity to induce seizures was in use as ] (ECT) by 1938.<ref>{{cite journal |vauthors=Ali SA, Mathur N, Malhotra AK, Braga RJ |date=April 2019 |title=Electroconvulsive Therapy and Schizophrenia: A Systematic Review |journal=Molecular Neuropsychiatry |volume=5 |issue=2 |pages=75–83 |doi=10.1159/000497376 |pmc=6528094 |pmid=31192220}}</ref>


Carried out from the 1930s until the 1970s in the United States and until the 1980s in France, ], including such modalities as the ], is recognized as a ].<ref>{{cite journal |vauthors=Mashour GA, Walker EE, Martuza RL |date=June 2005 |title=Psychosurgery: past, present, and future |journal=Brain Research. Brain Research Reviews |volume=48 |issue=3 |pages=409–419 |doi=10.1016/j.brainresrev.2004.09.002 |pmid=15914249 |s2cid=10303872}}</ref><ref>{{Cite web |vauthors=Mendez J |date=1 February 2013|title=Report of the Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment |url= https://www.ohchr.org/sites/default/files/Documents/HRBodies/HRCouncil/RegularSession/Session22/A.HRC.22.53_English.pdf |access-date= 22 August 2022 |publisher=Office of the High Commissioner for Human Rights}}</ref> In the mid-1950s, ], the first ], was introduced,<ref>{{cite journal |vauthors=Turner T |date=January 2007 |title=Chlorpromazine: unlocking psychosis |journal=BMJ |volume=334 Suppl 1 |issue=suppl |page=s7 |doi=10.1136/bmj.39034.609074.94 |pmid=17204765 |s2cid=33739419}}</ref> followed in the 1970s by clozapine, the first ].<ref>{{cite journal |vauthors=Aringhieri S |date=December 2018 |title=Molecular targets of atypical antipsychotics: From mechanism of action to clinical differences. |journal=Pharmacology & Therapeutics |volume=192 |pages=20–41 |doi=10.1016/j.pharmthera.2018.06.012 |pmid=29953902 |s2cid=49602956}}</ref>
One theory put forward by psychiatrists ] and R.H. Yolken is that the parasite ] leads to some, if not many, cases of schizophrenia.<ref name="fn_58"> Toxoplasma gondii and schizophrenia. ''Emerging Infectious Diseases'', 9 (11), 1375-80.</ref> This is supported by evidence that significantly higher levels of Toxoplasma antibodies in schizophrenia patients compared to the general population.<ref>Wang HL, ''et al.'' (2006) , ''Acta Psychiatrica Scandinavica'', 114 (1), 40-48.</ref>


=== Political abuse ===
An additional approach is suggested by the work of ] who argues that "The usual difference between someone who hallucinates and someone who visualizes normally, is that the person who hallucinates doesn't know he's doing it or doesn't have any choice about it." ('']'', p107). He suggests that because visualization is a sophisticated mental capability, schizophrenia is a skill, albeit an involuntary and dysfunctional one that is being used but not controlled. He therefore suggests that a significant route to treating schizophrenia might be to teach the missing skill - how to distinguish created reality from consensus external reality, to reduce its maladaptive impact, and ultimately how to exercise appropriate control over the vizualization or auditory process. Hypnotic approaches have been explored by the physician ] as a means of facilitating this.
{{Further information|Political abuse of psychiatry}}
From the 1960s until 1989, psychiatrists in the ] and ] diagnosed thousands of people with ],<ref>{{Cite journal|vauthors=Park YS, Sang M, Jun JY, Kim SJ|date=2014|title=Psychiatry in former socialist countries: implications for north korean psychiatry|journal=Psychiatry Investigation|volume=11|issue=4|pages=363–370|doi=10.4306/pi.2014.11.4.363|issn=1738-3684|pmc=4225199|pmid=25395966}}</ref><ref>{{page needed|date=August 2022}} {{Cite book|vauthors=Gosden R|title=Punishing the patient: how psychiatrists misunderstand and mistreat schizophrenia|date=2001|publisher=Scribe Publications|isbn=0-908011-52-0|location=Melbourne|oclc=47177633}}</ref> without signs of psychosis, based on "the assumption that symptoms would later appear".<ref>{{cite journal | vauthors = Sfera A | title = Can Psychiatry be Misused Again? | journal = Frontiers in Psychiatry | volume = 4 | pages = 101 | date = September 2013 | pmid = 24058348 | pmc = 3766833 | doi = 10.3389/fpsyt.2013.00101 | doi-access = free }}</ref> Now discredited, the diagnosis provided a convenient way to confine political dissidents.<ref name=Merskey1988>{{Cite journal| vauthors = Merskey H |date=15 October 1988|title=IPPNW: Forum for Soviet anti-American propaganda?|journal=CMAJ: Canadian Medical Association Journal|volume=139|issue=8|pages=699–700|issn=0820-3946|pmc=1268271}}</ref>


==Society and culture==
Regarding schizophrenia as a waking dreamer syndrome, Jie Zhang hypothesizes that the hallucinations of schizophrenia are caused by the activation of the continual-activation mechanism during waking, a mechanism that induces dreaming while asleep, due to the malfunction of the continual-activation thresholds in the conscious part of brain.<ref name="fn_69">Zhang, Jie (2005) , Dynamical Psychology.<br></ref>
{{See also|List of people with schizophrenia|Religion and schizophrenia|}}In the United States, the annual cost of schizophrenia – including direct costs (outpatient, inpatient, drugs, and long-term care) and non-healthcare costs (law enforcement, reduced workplace productivity, and unemployment) – was estimated at $62.7&nbsp;billion for the year 2002.<ref>{{cite journal | vauthors = Wu EQ, Birnbaum HG, Shi L, Ball DE, Kessler RC, Moulis M, Aggarwal J | title = The economic burden of schizophrenia in the United States in 2002 | journal = The Journal of Clinical Psychiatry | volume = 66 | issue = 9 | pages = 1122–1129 | date = September 2005 | pmid = 16187769 | doi = 10.4088/jcp.v66n0906 }}</ref>{{efn|A 2007 review stated that the 2002 estimate was still the best available,<ref>{{cite journal | vauthors = McEvoy JP | title = The costs of schizophrenia | journal = The Journal of Clinical Psychiatry | volume = 68 | issue = Suppl 14 | pages = 4–7 | date = 2007 | pmid = 18284271 | doi = }}</ref> and a 2018 review cited the same $62.7&nbsp;billion.<ref>
{{cite journal |vauthors=Zhang W, Amos TB, Gutkin SW, et al |title=A systematic literature review of the clinical and health economic burden of schizophrenia in privately insured patients in the United States |journal=Clinicoecon Outcomes Res |volume=10 |issue= |pages=309–320 |date=2018 |pmid=29922078 |pmc=5997131 |doi=10.2147/CEOR.S156308 |doi-access=free }}</ref>}} In the UK the cost in 2016 was put at £11.8&nbsp;billion per year with a third of that figure directly attributable to the cost of hospital, social care and treatment.<ref name="Lancet2016" />


=== Stigma ===
==Portrayals of schizophrenia in the arts==
], an American mathematician and joint recipient of the 1994 ], had schizophrenia. His life was the subject of the 1998 book, '']'', by ].]]
The book and film '']'' chronicled the life of ], a ]-winning mathematician who was diagnosed with schizophrenia.


In 2002, the term for schizophrenia in Japan was changed from {{nihongo||精神分裂病|seishin-bunretsu-byō|lit. 'mind-split disease'}} to {{nihongo||統合失調症|tōgō-shitchō-shō|lit. 'integration–dysregulation syndrome'}} to reduce ].<ref>{{cite journal | vauthors = Yamaguchi S, Mizuno M, Ojio Y, Sawada U, Matsunaga A, Ando S, Koike S | title = Associations between renaming schizophrenia and stigma-related outcomes: A systematic review | journal = Psychiatry and Clinical Neurosciences | volume = 71 | issue = 6 | pages = 347–362 | date = June 2017 | pmid = 28177184 | doi = 10.1111/pcn.12510 | doi-access = free }}</ref> The new name, also interpreted as "integration disorder", was inspired by the biopsychosocial model.<ref>{{cite journal | vauthors = Sato M | title = Renaming schizophrenia: a Japanese perspective | journal = World Psychiatry | volume = 5 | issue = 1 | pages = 53–55 | date = February 2006 | pmid = 16757998 | pmc = 1472254 }}</ref> A similar change was made in South Korea in 2012 to attunement disorder.<ref>{{cite journal | vauthors = Park SC, Park YC | title = Korea in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition | journal = Journal of Korean Medical Science | volume = 35 | issue = 2 | pages = e6 | date = January 2020 | pmid = 31920014 | pmc = 6955430 | doi = 10.3346/jkms.2020.35.e6 | edition = Fifth }}</ref>
The effects of untreated schizophrenia on the family are documented in Virginia Holman's autobiography, Rescuing Patty Hearst, (Simon & Schuster 2003) The book also discusses the legal impediments to treatment that faces many schizophrenics and their families.


=== Cultural depictions ===
In Bulgakov's ''Master and Margarita'' the poet Ivan Bezdomnyj is institutionalized and diagnosed with schizophrenia after witnessing the devil (Woland) predict Berlioz's death.
Media coverage, especially movies, reinforce the public perception of an association between schizophrenia and violence.<ref>{{cite journal | vauthors = Fazel S, Gulati G, Linsell L, Geddes JR, Grann M | title = Schizophrenia and violence: systematic review and meta-analysis | journal = PLOS Medicine | volume = 6 | issue = 8 | pages = e1000120 | date = August 2009 | pmid = 19668362 | pmc = 2718581 | doi = 10.1371/journal.pmed.1000120 | doi-access = free }}</ref> A majority of movies have historically depicted characters with schizophrenia as criminal, dangerous, violent, unpredictable and homicidal, and depicted delusions and hallucinations as the main symptoms of schizophrenic characters, ignoring other common symptoms,<ref name= Owen2012>{{cite journal |vauthors=Owen PR |title=Portrayals of schizophrenia by entertainment media: a content analysis of contemporary movies |journal=Psychiatr Serv |volume=63 |issue=7 |pages=655–9 |date=July 2012 |pmid=22555313 |doi=10.1176/appi.ps.201100371}}</ref> furthering stereotypes of schizophrenia including the idea of a split personality.<ref>{{cite journal |vauthors=Katschnig H |title=Psychiatry's contribution to the public stereotype of schizophrenia: Historical considerations |journal=J Eval Clin Pract |volume=24 |issue=5 |pages=1093–1100 |date=October 2018 |pmid=30112785 |pmc=6174929 |doi=10.1111/jep.13011 }}</ref>


The book '']'' chronicled the life of ] who had been diagnosed with schizophrenia and won the ]. The book was made into a ]; an earlier documentary film was '']''.
==See also==
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* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* '']''
* ]
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* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
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In the UK, guidelines for reporting conditions and award campaigns have shown a reduction in negative reporting since 2013.<ref>{{cite journal |vauthors=Chen M, Lawrie S |title=Newspaper depictions of mental and physical health. |journal=BJPsych Bulletin |volume=41 |issue=6 |pages=308–313 |date=December 2017 |pmid=29234506 |doi=10.1192/pb.bp.116.054775|pmc=5709678 }}</ref>
Further information about schizophrenia and approaches to it, suggested by authors such as ], ], ], ], ], ], ] and ], as well as books, can be found within the articles for those authors.


In 1964 a ] of three males diagnosed with schizophrenia who each had the delusional belief that they were ] was published as '']''; a film with the title '']'' was released in 2020.<ref>{{cite journal | vauthors = Dyga K, Stupak R | title = Ways of understanding of religious delusions associated with a change of identity on the example of identification with Jesus Christ. | journal=Psychiatria Polska | date = 28 February 2018 | volume = 52 | issue = 1 | pages = 69–80 | doi=10.12740/PP/64378 | pmid=29704415| doi-access = free }}</ref><ref>{{cite journal | vauthors = Dein S, Littlewood R | title = Religion and psychosis: a common evolutionary trajectory? | journal = Transcultural Psychiatry | date = July 2011 | volume = 48 | issue = 3 | pages =318–335 | doi = 10.1177/1363461511402723 | pmid = 21742955| s2cid = 12991391 }}</ref>
==References==
<div class="references-small" style="-moz-column-count:2; column-count:2;">
<references />
</div>


==Further reading== ==Research directions==
{{See also|Animal models of schizophrenia}}
<!-- Please only include material which addresses schizophrenia in general, rather than specific aspects, or related topics -->
A 2015 Cochrane review found unclear evidence of benefit from brain stimulation techniques to treat the positive symptoms of schizophrenia, in particular auditory verbal hallucinations (AVHs).<ref>{{cite journal |vauthors =Dougall N, Maayan N, Soares-Weiser K, McDermott LM, McIntosh A |title=Transcranial magnetic stimulation (TMS) for schizophrenia. |journal=The Cochrane Database of Systematic Reviews |volume=2015 |date=20 August 2015 |issue=8 |pages=CD006081 |doi=10.1002/14651858.CD006081.pub2 |pmid=26289586|pmc=9395125 |hdl=1893/22520 |hdl-access=free }}</ref> Most studies focus on ] (tDCM), and ] (rTMS).<ref name=Nathou2019>{{cite journal |vauthors=Nathou C, Etard O, Dollfus S |date=2019 |title=Auditory verbal hallucinations in schizophrenia: current perspectives in brain stimulation treatments. |journal=Neuropsychiatric Disease and Treatment|volume=15 |pages=2105–2117 |pmid=31413576 |pmc=6662171 |doi=10.2147/NDT.S168801 |doi-access=free }}</ref> Techniques based on focused ultrasound for ] could provide insight for the treatment of AVHs.<ref name=Nathou2019/>
<div class="references-small">
* ] (2003) ''Madness explained: Psychosis and Human Nature''. London: Penguin Books Ltd. ISBN 0-7139-9249-2
* Boyle, Mary, (1993), ''Schizophrenia: A Scientific Delusion'', Routledge, ISBN 0-415-09700-2 ().
* Deveson, Anne (1991), "Tell Me I'm Here" NON-FICTION: Schizophrenics - biography - family relationships. ISBN 0-14-027257-7 PENGUIN GROUP Australia. Printed 1991 & 1998.
* ] et. al. (2003) ''The Neuroanatomy of Schizophrenia: Circuitry and Neurotransmitter Systems.'' Clinical Neuroscience Research 3:77-107.
* Green, M.F. (2001) ''Schizophrenia Revealed: From Neurons to Social Interactions''. New York: W.W. Norton. ISBN 0-393-70334-7
* Jones, S. and Hayward, P. (2004) ''Coping with Schizophrenia: A Guide for Patients, Families and Caregivers''. ISBN 1-85168-344-5
* ''Schizophrenia: orthodoxy and heresies. A review of alternative possibilities.'' Journal of Psychiatric and Mental Health Nursing, 1999, 6, 415-424. . An article reviewing the dominant (orthodox) and alternative (heretical) theories, hypotheses and beliefs about schizophrenia.
* Read, J., Mosher, L.R., Bentall, R. (2004) ''Models of Madness: Psychological, Social and Biological Approaches to Schizophrenia''. ISBN 1-58391-906-6. A critical approach to biological and genetic theories, and a review of social influences on schizophrenia.
* ] (1976) ''Schizophrenia: The Sacred Symbol of Psychiatry''. New York: Basic Books. ISBN 0-465-07222-4
* ] : "Sexuality, War, and Schizophrenia: Collected ] Papers", Publisher: Transaction Publishers 1991, ISBN 0-88738-365-3 (])
* ] (2006) ''Surviving Schizophrenia: A Manual for Families, Consumers, and Providers (5th Edition)''. Quill (HarperCollins Publishers) ISBN 0-06-084259-8
* ] ''The Eden Express''. ISBN 0-553-02755-7. A personal account of schizophrenia.
</div>


The study of potential ] that would help in diagnosis and treatment of schizophrenia is an active area of research as of 2020. Possible biomarkers include markers of inflammation,<ref name=Upthegrove2020/> ],<ref>{{cite journal |vauthors=Kraguljac NV, McDonald WM, Widge AS, Rodriguez CI, Tohen M, Nemeroff CB |title=Neuroimaging Biomarkers in Schizophrenia |journal=Am J Psychiatry |pages=509–521 |date=January 2021 |volume=178 |issue=6 |pmid=33397140 |doi=10.1176/appi.ajp.2020.20030340|pmc=8222104 }}</ref> ] (BDNF),<ref>{{cite journal |vauthors=Khavari B, Cairns MJ |title=Epigenomic Dysregulation in Schizophrenia: In Search of Disease Etiology and Biomarkers |journal=Cells |volume=9 |issue=8 |date=August 2020 |page=1837 |pmid=32764320 |doi=10.3390/cells9081837|pmc=7463953 |doi-access=free }}</ref> and speech analysis. Some markers such as ] are useful in detecting levels of inflammation implicated in some psychiatric disorders but they are not disorder-specific. Other inflammatory cytokines are found to be elevated in first episode psychosis and acute relapse that are normalized after treatment with antipsychotics, and these may be considered as state markers.<ref>{{cite journal |vauthors=Goldsmith DR, Crooks CL, Walker EF, Cotes RO |title=An Update on Promising Biomarkers in Schizophrenia |journal=Focus (American Psychiatric Publishing)|volume=16 |issue=2 |pages=153–163 |date=April 2018 |doi=10.1176/appi.focus.20170046 |pmid=31975910|pmc=6526854 }}</ref> Deficits in ]s in schizophrenia may serve as a marker of an impaired thalamocortical circuit, and a mechanism for memory impairment.<ref name=Pocivavsek2018>{{cite journal |vauthors=Pocivavsek A, Rowland LM |title=Basic Neuroscience Illuminates Causal Relationship Between Sleep and Memory: Translating to Schizophrenia |journal=Schizophrenia Bulletin |volume=44 |issue=1 |pages=7–14 |date=13 January 2018 |pmid=29136236|doi=10.1093/schbul/sbx151|pmc=5768044 |doi-access=free }}</ref> ]s are highly influential in early neuronal development, and their disruption is implicated in several ] disorders; ]s (cimiRNAs) are found in ]s such as blood and cerebrospinal fluid, and changes in their levels are seen to relate to changes in microRNA levels in specific regions of brain tissue. These studies suggest that cimiRNAs have the potential to be early and accurate biomarkers in a number of disorders including schizophrenia.<ref>{{cite journal |vauthors=Kumar S, Reddy PH |title=Are circulating microRNAs peripheral biomarkers for Alzheimer's disease? |journal=Biochim Biophys Acta |volume=1862 |issue=9 |pages=1617–1627 |date=September 2016 |pmid=27264337 |pmc=5343750 |doi=10.1016/j.bbadis.2016.06.001 |url=}}</ref><ref>{{cite journal |vauthors=van den Berg MM, Krauskopf J, Ramaekers JG, et al. |title=Circulating microRNAs as potential biomarkers for psychiatric and neurodegenerative disorders |journal=Prog Neurobiol |volume=185 |pages=101732 |date=February 2020 |pmid=31816349 |doi=10.1016/j.pneurobio.2019.101732 |s2cid=208790466|doi-access=free }}</ref>
==External links==
===News, information and further description===
* - DSM V scholarly debates on schizophrenia
* - NPR: the sight and sounds of schizophrenia
*
* - A factsheet from the mental health charity ''Mind''
*
* from 'The World Health Report 2001. Mental Health: New Understanding, New Hope'
*
*
*
*
*
* by ] (pharmaceutical company sponsored).
* - information and support site
*
* Film made in 1940 showing some of the symptoms of Schizophrenia.
*
*
*
*


] aims to identify biomarkers within these brain networks,<ref>{{Cite journal |last1=Palaniyappan |first1=Lena |last2=Liddle |first2=Peter F. |date=2013-04-24 |title=Diagnostic Discontinuity in Psychosis: A Combined Study of Cortical Gyrification and Functional Connectivity |url=https://academic.oup.com/schizophreniabulletin/article-abstract/40/3/675/1903745?redirectedFrom=fulltext |journal=Schizophrenia Bulletin |volume=40 |issue=3 |pages=675–684 |doi=10.1093/schbul/sbt050 |issn=1745-1701 |pmc=3984507 |pmid=23615812}}</ref> potentially aiding in earlier diagnosis and better tracking of treatment responses in schizophrenia.
===Charities and support groups===
*
* UK mental health charity focused on schizophrenia that supports sufferers, runs a helpline and carries out research into mental illness
*
* The Campaign for Abolition of the Schizophrenia Label.


== Explanatory notes ==
===Critical approaches to schizophrenia===
{{Notelist}}
* A website critical of Schizophrenia as a disorder, with many links and resources, by ], psychologist Ph.D.
* by Lawrence Stevens, J.D
* Loren Mosher, M.D. (Chief of the Center for Studies of Schizophrenia at the U.S. National Institute of Mental Health 1969-1980)
* Bola, John R., Ph.D.; & Mosher, Loren R., M.D. (2003). Treatment of Acute Psychosis Without Neuroleptics: Two-Year Outcomes From the Soteria Project. ''The Journal of Nervous and Mental Disease'', (191: 219-229). .
* Jonathan Leo, Ph.D., & Jay Joseph, Psy.D.


== References ==
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== External links ==
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{{Medical condition classification and resources
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| ICD10 = {{ICD10|F|20||f|20}}
| ICD9 = {{ICD9|295}}
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| OMIM = 181500
| MedlinePlus = 000928
| eMedicineSubj = med
| eMedicineTopic = 2072
| eMedicine_mult = {{eMedicine2|emerg|520}}
| MeshName = Schizophrenia
| MeshNumber = F03.700.750
| Scholia = Q41112
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{{Schizophrenia}}
{{Mental and behavioural disorders|selected = schizophrenia}}
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Latest revision as of 21:08, 22 December 2024

Mental disorder with psychotic symptoms For other uses, see Schizophrenia (disambiguation).

Medical condition
Schizophrenia
Embroidery art with nonlinear text sewn into it with multiple colors of thread
Cloth embroidered by a person diagnosed with schizophrenia
SpecialtyPsychiatry
SymptomsHallucinations, delusions, disorganized thinking and behavior, flat or inappropriate affect
ComplicationsHarm to self or others, social isolation, cognitive issues, heart disease, lifestyle diseases, obesity and type 2 diabetes arising from antipsychotic medication
Usual onsetAges 16 to 30
DurationChronic
CausesEnvironmental and genetic factors
Risk factorsFamily history, cannabis use in adolescence, hallucinogen- or amphetamine-associated psychosis, problems during pregnancy, childhood adversity, being born or raised in a city
Diagnostic methodBased on observed behavior, reported experiences, and reports of others familiar with the person
Differential diagnosisSubstance use disorder, Huntington's disease, mood disorders (bipolar disorder, major depressive disorder), autism, borderline personality disorder, schizophreniform disorder, schizotypal personality disorder, schizoid personality disorder, antisocial personality disorder, psychotic depression, anxiety, disruptive mood dysregulation disorder, sleep paralysis
ManagementCounseling, life skills training
MedicationAntipsychotics
Prognosis20–28 years shorter life expectancy
Frequency~0.32% (1 in 300) of the global population is affected.
Deaths~17,000 (2015)

Schizophrenia is a mental disorder characterized variously by hallucinations (typically, hearing voices), delusions, disorganized thinking and behavior, and flat or inappropriate affect. Symptoms develop gradually and typically begin during young adulthood and are never resolved. There is no objective diagnostic test; diagnosis is based on observed behavior, a psychiatric history that includes the person's reported experiences, and reports of others familiar with the person. For a diagnosis of schizophrenia, the described symptoms need to have been present for at least six months (according to the DSM-5) or one month (according to the ICD-11). Many people with schizophrenia have other mental disorders, especially mood disorders, anxiety disorders, and obsessive–compulsive disorder.

About 0.3% to 0.7% of people are diagnosed with schizophrenia during their lifetime. In 2017, there were an estimated 1.1 million new cases and in 2022 a total of 24 million cases globally. Males are more often affected and on average have an earlier onset than females. The causes of schizophrenia may include genetic and environmental factors. Genetic factors include a variety of common and rare genetic variants. Possible environmental factors include being raised in a city, childhood adversity, cannabis use during adolescence, infections, the age of a person's mother or father, and poor nutrition during pregnancy.

About half of those diagnosed with schizophrenia will have a significant improvement over the long term with no further relapses, and a small proportion of these will recover completely. The other half will have a lifelong impairment. In severe cases, people may be admitted to hospitals. Social problems such as long-term unemployment, poverty, homelessness, exploitation, and victimization are commonly correlated with schizophrenia. Compared to the general population, people with schizophrenia have a higher suicide rate (about 5% overall) and more physical health problems, leading to an average decrease in life expectancy by 20 to 28 years. In 2015, an estimated 17,000 deaths were linked to schizophrenia.

The mainstay of treatment is antipsychotic medication, including olanzapine and risperidone, along with counseling, job training, and social rehabilitation. Up to a third of people do not respond to initial antipsychotics, in which case clozapine is offered. In a network comparative meta-analysis of 15 antipsychotic drugs, clozapine was significantly more effective than all other drugs, although clozapine's heavily multimodal action may cause more significant side effects. In situations where doctors judge that there is a risk of harm to self or others, they may impose short involuntary hospitalization. Long-term hospitalization is used on a small number of people with severe schizophrenia. In some countries where supportive services are limited or unavailable, long-term hospital stays are more common.

Signs and symptoms

My Eyes at the Moment of the Apparitions by German artist August Natterer, who had schizophrenia

Schizophrenia is a mental disorder characterized by significant alterations in perception, thoughts, mood, and behavior. Symptoms are described in terms of positive, negative, and cognitive symptoms. The positive symptoms of schizophrenia are the same for any psychosis and are sometimes referred to as psychotic symptoms. These may be present in any of the different psychoses and are often transient, making early diagnosis of schizophrenia problematic. Psychosis noted for the first time in a person who is later diagnosed with schizophrenia is referred to as a first-episode psychosis (FEP).

Positive symptoms

Positive symptoms are those symptoms that are not normally experienced, but are present in people during a psychotic episode in schizophrenia, including delusions, hallucinations, and disorganized thoughts, speech and behavior or inappropriate affect, typically regarded as manifestations of psychosis. Hallucinations occur at some point in the lifetimes of 80% of those with schizophrenia and most commonly involve the sense of hearing (most often hearing voices), but can sometimes involve any of the other senses such as taste, sight, smell, and touch. The frequency of hallucinations involving multiple senses is double the rate of those involving only one sense. They are also typically related to the content of the delusional theme. Delusions are bizarre or persecutory in nature. Distortions of self-experience such as feeling that others can hear one's thoughts or that thoughts are being inserted into one's mind, sometimes termed passivity phenomena, are also common. Positive symptoms generally respond well to medication and become reduced over the course of the illness, perhaps linked to the age-related decline in dopamine activity.

Negative symptoms

Negative symptoms are deficits of normal emotional responses, or of other thought processes. The five recognized domains of negative symptoms are: blunted affect – showing flat expressions (monotone) or little emotion; alogia – a poverty of speech; anhedonia – an inability to feel pleasure; asociality – the lack of desire to form relationships, and avolition – a lack of motivation and apathy. Avolition and anhedonia are seen as motivational deficits resulting from impaired reward processing. Reward is the main driver of motivation and this is mostly mediated by dopamine. It has been suggested that negative symptoms are multidimensional and they have been categorised into two subdomains of apathy or lack of motivation, and diminished expression. Apathy includes avolition, anhedonia, and social withdrawal; diminished expression includes blunt affect and alogia. Sometimes diminished expression is treated as both verbal and non-verbal.

Apathy accounts for around 50% of the most often found negative symptoms and affects functional outcome and subsequent quality of life. Apathy is related to disrupted cognitive processing affecting memory and planning including goal-directed behaviour. The two subdomains have suggested a need for separate treatment approaches. A lack of distress is another noted negative symptom. A distinction is often made between those negative symptoms that are inherent to schizophrenia, termed primary; and those that result from positive symptoms, from the side effects of antipsychotics, substance use disorder, and social deprivation – termed secondary negative symptoms. Negative symptoms are less responsive to medication and the most difficult to treat. However, if properly assessed, secondary negative symptoms are amenable to treatment. There is some evidence that the negative symptoms of schizophrenia are amenable to psychostimulant medication, although such drugs have varying degrees of risk for causing positive psychotic symptoms.

Scales for specifically assessing the presence of negative symptoms, and for measuring their severity, and their changes have been introduced since the earlier scales such as the PANNS that deals with all types of symptoms. These scales are the Clinical Assessment Interview for Negative Symptoms (CAINS), and the Brief Negative Symptom Scale (BNSS) also known as second-generation scales. In 2020, ten years after its introduction, a cross-cultural study of the use of BNSS found valid and reliable psychometric evidence for its five-domain structure cross-culturally. The BNSS can assess both the presence and severity of negative symptoms of the five recognized domains and an additional item of reduced normal distress. It has been used to measure changes in negative symptoms in trials of psychosocial and pharmacological interventions.

Cognitive symptoms

See also: Visual processing abnormalities in schizophrenia
Map of deficits in neural tissue throughout the human brain in a patient with schizophrenia. The most deficient areas are magenta, while the least deficient areas are blue.

An estimated 70% of those with schizophrenia have cognitive deficits, and these are most pronounced in early-onset and late-onset illness. These are often evident long before the onset of illness in the prodromal stage, and may be present in childhood or early adolescence. They are a core feature but not considered to be core symptoms, as are positive and negative symptoms. However, their presence and degree of dysfunction is taken as a better indicator of functionality than the presentation of core symptoms. Cognitive deficits become worse at first episode psychosis but then return to baseline, and remain fairly stable over the course of the illness.

The deficits in cognition are seen to drive the negative psychosocial outcome in schizophrenia, and are claimed to equate to a possible reduction in IQ from the norm of 100 to 70–85. Cognitive deficits may be of neurocognition (nonsocial) or of social cognition. Neurocognition is the ability to receive and remember information, and includes verbal fluency, memory, reasoning, problem solving, speed of processing, and auditory and visual perception. Verbal memory and attention are seen to be the most affected. Verbal memory impairment is associated with a decreased level of semantic processing (relating meaning to words). Another memory impairment is that of episodic memory. An impairment in visual perception that is consistently found in schizophrenia is that of visual backward masking. Visual processing impairments include an inability to perceive complex visual illusions. Social cognition is concerned with the mental operations needed to interpret, and understand the self and others in the social world. This is also an associated impairment, and facial emotion perception is often found to be difficult. Facial perception is critical for ordinary social interaction. Cognitive impairments do not usually respond to antipsychotics, and there are a number of interventions that are used to try to improve them; cognitive remediation therapy is of particular help.

Neurological soft signs of clumsiness and loss of fine motor movement are often found in schizophrenia, which may resolve with effective treatment of FEP.

Onset

Further information: Basic symptoms of schizophrenia See also: Childhood schizophrenia and Adolescence § Changes in the brain

Onset typically occurs between the late teens and early 30s, with the peak incidence occurring in males in the early to mid-twenties, and in females in the late twenties. Onset before the age of 17 is known as early-onset, and before the age of 13, as can sometimes occur, is known as childhood schizophrenia or very early-onset. Onset can occur between the ages of 40 and 60, known as late-onset schizophrenia. Onset over the age of 60, which may be difficult to differentiate as schizophrenia, is known as very-late-onset schizophrenia-like psychosis. Late onset has shown that a higher rate of females are affected; they have less severe symptoms and need lower doses of antipsychotics. The tendency for earlier onset in males is later seen to be balanced by a post-menopausal increase in the development in females. Estrogen produced pre-menopause has a dampening effect on dopamine receptors but its protection can be overridden by a genetic overload. There has been a dramatic increase in the numbers of older adults with schizophrenia.

Onset may happen suddenly or may occur after the slow and gradual development of a number of signs and symptoms, a period known as the prodromal stage. Up to 75% of those with schizophrenia go through a prodromal stage. The negative and cognitive symptoms in the prodrome stage can precede FEP (first episode psychosis) by many months and up to five years. The period from FEP and treatment is known as the duration of untreated psychosis (DUP) which is seen to be a factor in functional outcome. The prodromal stage is the high-risk stage for the development of psychosis. Since the progression to first episode psychosis is not inevitable, an alternative term is often preferred of at risk mental state. Cognitive dysfunction at an early age impacts a young person's usual cognitive development. Recognition and early intervention at the prodromal stage would minimize the associated disruption to educational and social development and has been the focus of many studies.

Risk factors

Main article: Risk factors of schizophrenia

Schizophrenia is described as a neurodevelopmental disorder with no precise boundary, or single cause, and is thought to develop from gene–environment interactions with involved vulnerability factors. The interactions of these risk factors are complex, as numerous and diverse insults from conception to adulthood can be involved. A genetic predisposition on its own, without interacting environmental factors, will not give rise to the development of schizophrenia. The genetic component means that prenatal brain development is disturbed, and environmental influence affects the postnatal development of the brain. Evidence suggests that genetically susceptible children are more likely to be vulnerable to the effects of environmental risk factors.

Genetic

Estimates of the heritability of schizophrenia are between 70% and 80%, which implies that 70% to 80% of the individual differences in risk of schizophrenia are associated with genetics. These estimates vary because of the difficulty in separating genetic and environmental influences, and their accuracy has been queried. The greatest risk factor for developing schizophrenia is having a first-degree relative with the disease (risk is 6.5%); more than 40% of identical twins of those with schizophrenia are also affected. If one parent is affected the risk is about 13% and if both are affected the risk is nearly 50%. However, the DSM-5 indicates that most people with schizophrenia have no family history of psychosis. Results of candidate gene studies of schizophrenia have generally failed to find consistent associations, and the genetic loci identified by genome-wide association studies explain only a small fraction of the variation in the disease.

Many genes are known to be involved in schizophrenia, each with small effects and unknown transmission and expression. The summation of these effect sizes into a polygenic risk score can explain at least 7% of the variability in liability for schizophrenia. Around 5% of cases of schizophrenia are understood to be at least partially attributable to rare copy number variations (CNVs); these structural variations are associated with known genomic disorders involving deletions at 22q11.2 (DiGeorge syndrome) and 17q12 (17q12 microdeletion syndrome), duplications at 16p11.2 (most frequently found) and deletions at 15q11.2 (Burnside–Butler syndrome). Some of these CNVs increase the risk of developing schizophrenia by as much as 20-fold, and are frequently comorbid with autism and intellectual disabilities.

The genes CRHR1 and CRHBP are associated with the severity of suicidal behavior. These genes code for stress response proteins needed in the control of the HPA axis, and their interaction can affect this axis. Response to stress can cause lasting changes in the function of the HPA axis possibly disrupting the negative feedback mechanism, homeostasis, and the regulation of emotion leading to altered behaviors.

The question of how schizophrenia could be primarily genetically influenced, given that people with schizophrenia have lower fertility rates, is a paradox. It is expected that genetic variants that increase the risk of schizophrenia would be selected against, due to their negative effects on reproductive fitness. A number of potential explanations have been proposed, including that alleles associated with schizophrenia risk confers a fitness advantage in unaffected individuals. While some evidence has not supported this idea, others propose that a large number of alleles each contributing a small amount can persist.

A meta-analysis found that oxidative DNA damage was significantly increased in schizophrenia.

Environmental

Further information: Prenatal nutrition, Prenatal stress, and Neuroplastic effects of pollution

Environmental factors, each associated with a slight risk of developing schizophrenia in later life include oxygen deprivation, infection, prenatal maternal stress, and malnutrition in the mother during prenatal development. A risk is associated with maternal obesity, in increasing oxidative stress, and dysregulating the dopamine and serotonin pathways. Both maternal stress and infection have been demonstrated to alter fetal neurodevelopment through an increase of pro-inflammatory cytokines. There is a slighter risk associated with being born in the winter or spring possibly due to vitamin D deficiency or a prenatal viral infection. Other infections during pregnancy or around the time of birth that have been linked to an increased risk include infections by Toxoplasma gondii and Chlamydia. The increased risk is about five to eight percent. Viral infections of the brain during childhood are also linked to a risk of schizophrenia during adulthood. Cat exposure is also associated with an increased risk of broadly defined schizophrenia-related disorders, with an odds ratio of 2.4.

Adverse childhood experiences (ACEs), severe forms of which are classed as childhood trauma, range from being bullied or abused, to the death of a parent. Many adverse childhood experiences can cause toxic stress and increase the risk of psychosis. Chronic trauma, including ACEs, can promote lasting inflammatory dysregulation throughout the nervous system. It is suggested that early stress may contribute to the development of schizophrenia through these alterations in the immune system. Schizophrenia was the last diagnosis to benefit from the link made between ACEs and adult mental health outcomes.

Living in an urban environment during childhood or as an adult has consistently been found to increase the risk of schizophrenia by a factor of two, even after taking into account drug use, ethnic group, and size of social group. A possible link between the urban environment and pollution has been suggested to be the cause of the elevated risk of schizophrenia. Other risk factors include social isolation, immigration related to social adversity and racial discrimination, family dysfunction, unemployment, and poor housing conditions. Having a father older than 40 years, or parents younger than 20 years are also associated with schizophrenia.

Substance use

Further information: Risk factors of schizophrenia § Substance use, and Substance-induced psychosis

About half of those with schizophrenia use recreational drugs including alcohol, tobacco, and cannabis excessively. Use of stimulants such as amphetamine and cocaine can lead to a temporary stimulant psychosis, which presents very similarly to schizophrenia. Rarely, alcohol use can also result in a similar alcohol-related psychosis. Drugs may also be used as coping mechanisms by people who have schizophrenia, to deal with depression, anxiety, boredom, and loneliness. The use of cannabis and tobacco are not associated with the development of cognitive deficits, and sometimes a reverse relationship is found where their use improves these symptoms. However, substance use disorders are associated with an increased risk of suicide, and a poor response to treatment.

Cannabis use may be a contributory factor in the development of schizophrenia, potentially increasing the risk of the disease in those who are already at risk. The increased risk may require the presence of certain genes within an individual. Its use is associated with doubling the rate.

Causes

Main article: Causes of schizophreniaSee also: Aberrant salience

The causes of schizophrenia are still unknown. Several models have been put forward to explain the link between altered brain function and schizophrenia. The prevailing model of schizophrenia is that of a neurodevelopmental disorder, and the underlying changes that occur before symptoms become evident are seen as arising from the interaction between genes and the environment. Extensive studies support this model. Maternal infections, malnutrition and complications during pregnancy and childbirth are known risk factors for the development of schizophrenia, which usually emerges between the ages of 18 and 25, a period that overlaps with certain stages of neurodevelopment. Gene-environment interactions lead to deficits in the neural circuitry that affect sensory and cognitive functions.

The common dopamine and glutamate models proposed are not mutually exclusive; each is seen to have a role in the neurobiology of schizophrenia. The most common model put forward was the dopamine hypothesis of schizophrenia, which attributes psychosis to the mind's faulty interpretation of the misfiring of dopaminergic neurons. This has been directly related to the symptoms of delusions and hallucinations. Abnormal dopamine signaling has been implicated in schizophrenia based on the usefulness of medications that affect the dopamine receptor and the observation that dopamine levels are increased during acute psychosis. A decrease in D1 receptors in the dorsolateral prefrontal cortex may also be responsible for deficits in working memory.

The glutamate hypothesis of schizophrenia links alterations between glutamatergic neurotransmission and the neural oscillations that affect connections between the thalamus and the cortex. Studies have shown that a reduced expression of a glutamate receptorNMDA receptor, and glutamate blocking drugs such as phencyclidine and ketamine can mimic the symptoms and cognitive problems associated with schizophrenia. Post-mortem studies consistently find that a subset of these neurons fail to express GAD67 (GAD1), in addition to abnormalities in brain morphometry. The subsets of interneurons that are abnormal in schizophrenia are responsible for the synchronizing of neural ensembles needed during working memory tasks. These give the neural oscillations produced as gamma waves that have a frequency of between 30 and 80 hertz. Both working memory tasks and gamma waves are impaired in schizophrenia, which may reflect abnormal interneuron functionality. An important process that may be disrupted in neurodevelopment is astrogenesis – the formation of astrocytes. Astrocytes are crucial in contributing to the formation and maintenance of neural circuits and it is believed that disruption in this role can result in a number of neurodevelopmental disorders including schizophrenia. Evidence suggests that reduced numbers of astrocytes in deeper cortical layers are assocociated with a diminished expression of EAAT2, a glutamate transporter in astrocytes; supporting the glutamate hypothesis.

Deficits in executive functions, such as planning, inhibition, and working memory, are pervasive in schizophrenia. Although these functions are separable, their dysfunction in schizophrenia may reflect an underlying deficit in the ability to represent goal related information in working memory, and to use this to direct cognition and behavior. These impairments have been linked to a number of neuroimaging and neuropathological abnormalities. For example, functional neuroimaging studies report evidence of reduced neural processing efficiency, whereby the dorsolateral prefrontal cortex is activated to a greater degree to achieve a certain level of performance relative to controls on working memory tasks. These abnormalities may be linked to the consistent post-mortem finding of reduced neuropil, evidenced by increased pyramidal cell density and reduced dendritic spine density. These cellular and functional abnormalities may also be reflected in structural neuroimaging studies that find reduced grey matter volume in association with deficits in working memory tasks.

Positive symptoms have been linked to cortical thinning in the superior temporal gyrus. The severity of negative symptoms has been linked to reduced thickness in the left medial orbitofrontal cortex. Anhedonia, traditionally defined as a reduced capacity to experience pleasure, is frequently reported in schizophrenia. However, a large body of evidence suggests that hedonic responses are intact in schizophrenia, and that what is reported to be anhedonia is a reflection of dysfunction in other processes related to reward. Overall, a failure of reward prediction is thought to lead to impairment in the generation of cognition and behavior required to obtain rewards, despite normal hedonic responses.

Another theory links abnormal brain lateralization to the development of being left-handed which is significantly more common in those with schizophrenia. This abnormal development of hemispheric asymmetry is noted in schizophrenia. Studies have concluded that the link is a true and verifiable effect that may reflect a genetic link between lateralization and schizophrenia.

Bayesian models of brain functioning have been used to link abnormalities in cellular functioning to symptoms. Both hallucinations and delusions have been suggested to reflect improper encoding of prior expectations, thereby causing expectation to excessively influence sensory perception and the formation of beliefs. In approved models of circuits that mediate predictive coding, reduced NMDA receptor activation, could in theory result in the positive symptoms of delusions and hallucinations.

Diagnosis

Main article: Diagnosis of schizophrenia

Criteria

Schizophrenia is diagnosed based on criteria in either the Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association or the International Statistical Classification of Diseases and Related Health Problems (ICD) published by the World Health Organization (WHO). These criteria use the self-reported experiences of the person and reported abnormalities in behavior, followed by a psychiatric assessment. The mental status examination is an important part of the assessment. An established tool for assessing the severity of positive and negative symptoms is the Positive and Negative Syndrome Scale (PANSS). This has been seen to have shortcomings relating to negative symptoms, and other scales – the Clinical Assessment Interview for Negative Symptoms (CAINS), and the Brief Negative Symptoms Scale (BNSS) have been introduced. The DSM-5, published in 2013, gives a Scale to Assess the Severity of Symptom Dimensions outlining eight dimensions of symptoms.

DSM-5 states that to be diagnosed with schizophrenia, two diagnostic criteria have to be met over the period of one month, with a significant impact on social or occupational functioning for at least six months. One of the symptoms needs to be either delusions, hallucinations, or disorganized speech. A second symptom could be one of the negative symptoms, or severely disorganized or catatonic behaviour. A different diagnosis of schizophreniform disorder can be made before the six months needed for the diagnosis of schizophrenia.

In Australia, the guideline for diagnosis is for six months or more with symptoms severe enough to affect ordinary functioning. In the UK diagnosis is based on having the symptoms for most of the time for one month, with symptoms that significantly affect the ability to work, study, or carry on ordinary daily living, and with other similar conditions ruled out.

The ICD criteria are typically used in European countries; the DSM criteria are used predominantly in the United States and Canada, and are prevailing in research studies. In practice, agreement between the two systems is high. The current proposal for the ICD-11 criteria for schizophrenia recommends adding self-disorder as a symptom.

A major unresolved difference between the two diagnostic systems is that of the requirement in DSM of an impaired functional outcome. WHO for ICD argues that not all people with schizophrenia have functional deficits and so these are not specific for the diagnosis.

Neuroimaging techniques

Functional magnetic resonance imaging (fMRI) has become a tool in understanding brain activity and connectivity differences in individuals with schizophrenia. Through resting-state fMRI, researchers have observed altered connectivity patterns within several key brain networks, such as the default mode network (DMN), salience network (SN), and central executive network (CEN). Alterations may underlie cognitive and emotional symptoms in schizophrenia, such as disorganized thinking, impaired attention, and emotional dysregulation.

Comorbidities

Euler diagram showing overlapping clinical phenotypes in genes associated with monogenic forms of autism spectrum disorder (ASD), dystonia, epilepsy and schizophrenia:   Genes associated with epilepsy   Genes associated with schizophrenia   Genes associated with autism spectrum disorder   Genes associated with dystonia

Many people with schizophrenia may have one or more other mental disorders, such as anxiety disorders, obsessive–compulsive disorder, or substance use disorder. These are separate disorders that require treatment. When comorbid with schizophrenia, substance use disorder and antisocial personality disorder both increase the risk for violence. Comorbid substance use disorder also increases the risk of suicide.

Sleep disorders often co-occur with schizophrenia, and may be an early sign of relapse. Sleep disorders are linked with positive symptoms such as disorganized thinking and can adversely affect cortical plasticity and cognition. The consolidation of memories is disrupted in sleep disorders. They are associated with severity of illness, a poor prognosis, and poor quality of life. Sleep onset and maintenance insomnia is a common symptom, regardless of whether treatment has been received or not. Genetic variations have been found associated with these conditions involving the circadian rhythm, dopamine and histamine metabolism, and signal transduction.

Schizophrenia is also associated with a number of somatic comorbidities including diabetes mellitus type 2, autoimmune diseases, and cardiovascular diseases. The association of these with schizophrenia may be partially due to medications (e.g. dyslipidemia from antipsychotics), environmental factors (e.g. complications from an increased rate of cigarette smoking), or associated with the disorder itself (e.g. diabetes mellitus type 2 and some cardiovascular diseases are thought to be genetically linked). These somatic comorbidities contribute to reduced life expectancy among persons with the disorder.

Differential diagnosis

See also: Dual diagnosis and Comparison of bipolar disorder and schizophrenia

To make a diagnosis of schizophrenia other possible causes of psychosis need to be excluded. Psychotic symptoms lasting less than a month may be diagnosed as brief psychotic disorder, or as schizophreniform disorder. Psychosis is noted in Other specified schizophrenia spectrum and other psychotic disorders as a DSM-5 category. Schizoaffective disorder is diagnosed if symptoms of mood disorder are substantially present alongside psychotic symptoms. Psychosis that results from a general medical condition or substance is termed secondary psychosis.

Psychotic symptoms may be present in several other conditions, including bipolar disorder, borderline personality disorder, substance intoxication, substance-induced psychosis, and a number of drug withdrawal syndromes. Non-bizarre delusions are also present in delusional disorder, and social withdrawal in social anxiety disorder, avoidant personality disorder and schizotypal personality disorder. Schizotypal personality disorder has symptoms that are similar but less severe than those of schizophrenia. Schizophrenia occurs along with obsessive–compulsive disorder (OCD) considerably more often than could be explained by chance, although it can be difficult to distinguish obsessions that occur in OCD from the delusions of schizophrenia. There can be considerable overlap with the symptoms of post-traumatic stress disorder.

A more general medical and neurological examination may be needed to rule out medical illnesses which may rarely produce psychotic schizophrenia-like symptoms, such as metabolic disturbance, systemic infection, syphilis, HIV-associated neurocognitive disorder, epilepsy, limbic encephalitis, and brain lesions. Stroke, multiple sclerosis, hyperthyroidism, hypothyroidism, and dementias such as Alzheimer's disease, Huntington's disease, frontotemporal dementia, and the Lewy body dementias may also be associated with schizophrenia-like psychotic symptoms. It may be necessary to rule out a delirium, which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness, and indicates an underlying medical illness. Investigations are not generally repeated for relapse unless there is a specific medical indication or possible adverse effects from antipsychotic medication. In children hallucinations must be separated from typical childhood fantasies. It is difficult to distinguish childhood schizophrenia from autism.

Prevention

Prevention of schizophrenia is difficult as there are no reliable markers for the later development of the disorder.

Early intervention programs diagnose and treat patients in the prodromal phase of the illness. There is some evidence that these programs reduce symptoms. Patients tend to prefer early treatment programs to ordinary treatment and are less likely to disengage from them. As of 2020, it is unclear whether the benefits of early treatment persist once the treatment is terminated.

Cognitive behavioral therapy may reduce the risk of psychosis in those at high risk after a year and is recommended in this group, by the National Institute for Health and Care Excellence (NICE). Another preventive measure is to avoid drugs that have been associated with development of the disorder, including cannabis, cocaine, and amphetamines.

Antipsychotics are prescribed following a first-episode psychosis, and following remission, a preventive maintenance use is continued to avoid relapse. However, it is recognized that some people do recover following a single episode and that long-term use of antipsychotics will not be needed but there is no way of identifying this group.

Management

Main article: Management of schizophrenia

The primary treatment of schizophrenia is the use of antipsychotic medications, often in combination with psychosocial interventions and social supports. Community support services including drop-in centers, visits by members of a community mental health team, supported employment, and support groups are common. The time between the onset of psychotic symptoms to being given treatment – the duration of untreated psychosis (DUP) – is associated with a poorer outcome in both the short term and the long term.

Voluntary or involuntary admission to hospital may be imposed by doctors and courts who deem a person to be having a severe episode. In the UK, large mental hospitals termed asylums began to be closed down in the 1950s with the advent of antipsychotics, and with an awareness of the negative impact of long-term hospital stays on recovery. This process was known as deinstitutionalization, and community and supportive services were developed to support this change. Many other countries followed suit with the US starting in the 60s. There still remain a smaller group of people who do not improve enough to be discharged. In some countries that lack the necessary supportive and social services, long-term hospital stays are more usual.

Medication

Risperidone (trade name Risperdal) is a common atypical antipsychotic medication.

The first-line treatment for schizophrenia is an antipsychotic. The first-generation antipsychotics, now called typical antipsychotics, like haloperidol, are dopamine antagonists that block D2 receptors, and affect the neurotransmission of dopamine. Those brought out later, the second-generation antipsychotics known as atypical antipsychotics, including olanzapine and risperidone, can also have an effect on another neurotransmitter, serotonin. Antipsychotics can reduce the symptoms of anxiety within hours of their use, but, for other symptoms, they may take several days or weeks to reach their full effect. They have little effect on negative and cognitive symptoms, which may be helped by additional psychotherapies and medications. There is no single antipsychotic suitable for first-line treatment for everyone, as responses and tolerances vary between people. Stopping medication may be considered after a single psychotic episode where there has been a full recovery with no symptoms for twelve months. Repeated relapses worsen the long-term outlook and the risk of relapse following a second episode is high, and long-term treatment is usually recommended.

About half of those with schizophrenia will respond favourably to antipsychotics, and have a good return of functioning. However, positive symptoms persist in up to a third of people. Following two trials of different antipsychotics over six weeks, that also prove ineffective, they will be classed as having treatment-resistant schizophrenia (TRS), and clozapine will be offered. Clozapine is of benefit to around half of this group although it has the potentially serious side effect of agranulocytosis (lowered white blood cell count) in less than 4% of people.

About 30 to 50 percent of people with schizophrenia do not accept that they have an illness or comply with their recommended treatment. For those who are unwilling or unable to take medication regularly, long-acting injections of antipsychotics may be used, which reduce the risk of relapse to a greater degree than oral medications. When used in combination with psychosocial interventions, they may improve long-term adherence to treatment.

The fixed-dose combination medication xanomeline/trospium chloride (Cobenfy) was approved for medical use in the United States in September 2024. It is the first cholinergic agonist approved by the US Food and Drug Administration (FDA) to treat schizophrenia.

Negative and cognitive symptoms are an unmet clinical need in antipsychotic-based treatment approaches. Psychostimulant drugs have been found effective in the treatment of negative symptoms, but are rarely prescribed due to concerns about the excacerbation of positive symptoms. It is possible that low-dose psychedelic therapies could be of benefit in schizophrenia through their prosocial and procognitive effects, although there is a serious risk that high dose psychedelic therapies could lead to worsening of positive symptoms.

Adverse effects

Further information: Antipsychotic § Adverse effects

Extrapyramidal symptoms, including akathisia, are associated with all commercially available antipsychotic to varying degrees. There is little evidence that second generation antipsychotics have reduced levels of extrapyramidical symptoms compared to typical antipsychotics. Tardive dyskinesia can occur due to long-term use of antipsychotics, developing after months or years of use. The antipsychotic clozapine is also associated with thromboembolism (including pulmonary embolism), myocarditis, and cardiomyopathy.

Psychosocial interventions

Further information: Management of schizophrenia § Psychosocial

A number of psychosocial interventions that include several types of psychotherapy may be useful in the treatment of schizophrenia such as: family therapy, group therapy, cognitive remediation therapy (CRT), cognitive behavioral therapy (CBT), and metacognitive training. Skills training, help with substance use, and weight management – often needed as a side effect of an antipsychotic – are also offered. In the US, interventions for first episode psychosis have been brought together in an overall approach known as coordinated speciality care (CSC) and also includes support for education. In the UK care across all phases is a similar approach that covers many of the treatment guidelines recommended. The aim is to reduce the number of relapses and stays in the hospital.

Other support services for education, employment, and housing are usually offered. For people with severe schizophrenia, who are discharged from a stay in the hospital, these services are often brought together in an integrated approach to offer support in the community away from the hospital setting. In addition to medicine management, housing, and finances, assistance is given for more routine matters such as help with shopping and using public transport. This approach is known as assertive community treatment (ACT) and has been shown to achieve positive results in symptoms, social functioning and quality of life. Another more intense approach is known as intensive care management (ICM). ICM is a stage further than ACT and emphasises support of high intensity in smaller caseloads, (less than twenty). This approach is to provide long-term care in the community. Studies show that ICM improves many of the relevant outcomes including social functioning.

Some studies have shown little evidence for the effectiveness of CBT in either reducing symptoms or preventing relapse. However, other studies have found that CBT does improve overall psychotic symptoms (when in use with medication) and it has been recommended in Canada, but has been seen to have no effect on social function, relapse, or quality of life. In the UK it is recommended as an add-on therapy in the treatment of schizophrenia. Arts therapies are seen to improve negative symptoms in some people, and are recommended by NICE in the UK. This approach is criticised as having not been well-researched, and arts therapies are not recommended in Australian guidelines for example. Peer support, in which people with personal experience of schizophrenia, provide help to each other, is of unclear benefit.

Other

Exercise including aerobic exercise has been shown to improve positive and negative symptoms, cognition, working memory, and improve quality of life. Exercise has also been shown to increase the volume of the hippocampus in those with schizophrenia. A decrease in hippocampal volume is one of the factors linked to the development of the disease. However, there still remains the problem of increasing motivation for, and maintaining participation in physical activity. Supervised sessions are recommended. In the UK healthy eating advice is offered alongside exercise programs.

An inadequate diet is often found in schizophrenia, and associated vitamin deficiencies including those of folate, and vitamin D are linked to the risk factors for the development of schizophrenia and for early death including heart disease. Those with schizophrenia possibly have the worst diet of all the mental disorders. Lower levels of folate and vitamin D have been noted as significantly lower in first episode psychosis. The use of supplemental folate is recommended. A zinc deficiency has also been noted. Vitamin B12 is also often deficient and this is linked to worse symptoms. Supplementation with B vitamins has been shown to significantly improve symptoms, and to put in reverse some of the cognitive deficits. It is also suggested that the noted dysfunction in gut microbiota might benefit from the use of probiotics.

Prognosis

Main article: Prognosis of schizophreniaSee also: Physical health in schizophrenia
Disability-adjusted life years lost due to schizophrenia per 100,000 inhabitants in 2004
  no data   ≤ 185   185–197   197–207   207–218   218–229   229–240   240–251   251–262   262–273   273–284   284–295   ≥ 295

Schizophrenia has great human and economic costs. It decreases life expectancy by between 10 and 28 years. This is primarily because of its association with heart disease, diabetes, obesity, poor diet, a sedentary lifestyle, and smoking, with an increased rate of suicide playing a lesser role. Side effects of antipsychotics may also increase the risk.

Almost 40% of those with schizophrenia die from complications of cardiovascular disease which is seen to be increasingly associated. An underlying factor of sudden cardiac death may be Brugada syndrome (BrS) – BrS mutations that overlap with those linked with schizophrenia are the calcium channel mutations. BrS may also be drug-induced from certain antipsychotics and antidepressants. Primary polydipsia, or excessive fluid intake, is relatively common in people with chronic schizophrenia. This may lead to hyponatremia which can be life-threatening. Antipsychotics can lead to a dry mouth, but there are several other factors that may contribute to the disorder; it may reduce life expectancy by 13 percent. Barriers to improving the mortality rate in schizophrenia are poverty, overlooking the symptoms of other illnesses, stress, stigma, and medication side effects.

Schizophrenia is a major cause of disability. In 2016, it was classed as the 12th most disabling condition. Approximately 75% of people with schizophrenia have ongoing disability with relapses. Some people do recover completely and others function well in society. Most people with schizophrenia live independently with community support. About 85% are unemployed. In people with a first episode of psychosis in schizophrenia a good long-term outcome occurs in 31%, an intermediate outcome in 42% and a poor outcome in 31%. Males are affected more often than females, and have a worse outcome. Studies showing that outcomes for schizophrenia appear better in the developing than the developed world have been questioned. Social problems, such as long-term unemployment, poverty, homelessness, exploitation, stigmatization and victimization are common consequences, and lead to social exclusion.

There is a higher than average suicide rate associated with schizophrenia estimated at 5% to 6%, most often occurring in the period following onset or first hospital admission. Several times more (20 to 40%) attempt suicide at least once. There are a variety of risk factors, including male sex, depression, a high IQ, heavy smoking, and substance use. Repeated relapse is linked to an increased risk of suicidal behavior. The use of clozapine can reduce the risk of suicide, and of aggression.

A strong association between schizophrenia and tobacco smoking has been shown in worldwide studies. Smoking is especially high in those diagnosed with schizophrenia, with estimates ranging from 80 to 90% being regular smokers, as compared to 20% of the general population. Those who smoke tend to smoke heavily, and additionally smoke cigarettes with high nicotine content. Some propose that this is in an effort to improve symptoms. Among people with schizophrenia use of cannabis is also common.

Schizophrenia leads to an increased risk of dementia.

Violence

Most people with schizophrenia are not aggressive, and are more likely to be victims of violence rather than perpetrators. People with schizophrenia are commonly exploited and victimized by violent crime as part of a broader dynamic of social exclusion. People diagnosed with schizophrenia are also subject to forced drug injections, seclusion, and restraint at high rates.

The risk of violence by people with schizophrenia is small. There are minor subgroups where the risk is high. This risk is usually associated with a comorbid disorder such as a substance use disorder – in particular alcohol, or with antisocial personality disorder. Substance use disorder is strongly linked, and other risk factors are linked to deficits in cognition and social cognition including facial perception and insight that are in part included in theory of mind impairments. Poor cognitive functioning, decision-making, and facial perception may contribute to making a wrong judgement of a situation that could result in an inappropriate response such as violence. These associated risk factors are also present in antisocial personality disorder which when present as a comorbid disorder greatly increases the risk of violence.

Epidemiology

Main article: Epidemiology of schizophrenia
Deaths per million persons due to schizophrenia in 2012   0–0  1–1  2–2  3–3  4–6  7–20

In 2017, the Global Burden of Disease Study estimated there were 1.1 million new cases; in 2022 the World Health Organization (WHO) reported a total of 24 million cases globally. Schizophrenia affects around 0.3–0.7% of people at some point in their life. In areas of conflict this figure can rise to between 4.0 and 6.5%. It occurs 1.4 times more frequently in males than females and typically appears earlier in men.

Worldwide, schizophrenia is the most common psychotic disorder. The frequency of schizophrenia varies across the world, within countries, and at the local and neighborhood level; this variation in prevalence between studies over time, across geographical locations, and by gender is as high as fivefold.

Schizophrenia causes approximately one percent of worldwide disability adjusted life years and resulted in 17,000 deaths in 2015.

In 2000, WHO found the percentage of people affected and the number of new cases that develop each year is roughly similar around the world, with age-standardized prevalence per 100,000 ranging from 343 in Africa to 544 in Japan and Oceania for men, and from 378 in Africa to 527 in Southeastern Europe for women.

History

Main article: History of schizophrenia

Conceptual development

Main article: History of schizophrenia § Conceptual development Further information: Dementia praecox
The term "schizophrenia" was coined by Eugen Bleuler.

Accounts of a schizophrenia-like syndrome are rare in records before the 19th century; the earliest case reports were in 1797 and 1809. The term dementia praecox ("premature dementia") was used by German psychiatrist Heinrich Schüle in 1886 and then in 1891 by Arnold Pick in a case report of hebephrenia. In 1893 Emil Kraepelin used the term in making a distinction, known as the Kraepelinian dichotomy, between the two psychoses: dementia praecox and manic depression (now called bipolar disorder). When it became evident that the disorder was not a degenerative dementia, it was renamed schizophrenia by Eugen Bleuler in 1908.

The word schizophrenia ("splitting of the mind") is Modern Latin, derived from the Greek schizein (Ancient Greek: σχίζειν, lit.'to split') and phrēn (Ancient Greek: φρήν, lit.'mind'). Its use was intended to describe the separation of function between personality, thinking, memory, and perception.

In the early 20th century, the psychiatrist Kurt Schneider categorized the psychotic symptoms of schizophrenia into two groups: hallucinations and delusions. The hallucinations were listed as specific to auditory and the delusions included thought disorders. These were seen as important symptoms, termed first-rank. The most common first-rank symptom was found to belong to thought disorders. In 2013 the first-rank symptoms were excluded from the DSM-5 criteria; while they may not be useful in diagnosing schizophrenia, they can assist in differential diagnosis.

Subtypes of schizophrenia—classified as paranoid, disorganized, catatonic, undifferentiated, and residual—were difficult to distinguish and are no longer recognized as separate conditions by DSM-5 (2013) or ICD-11.

Breadth of diagnosis

Before the 1960s, nonviolent petty criminals and women were sometimes diagnosed with schizophrenia, categorizing the latter as ill for not performing their duties as wives and mothers. In the mid- to late 1960s, black men were categorized as "hostile and aggressive" and diagnosed as schizophrenic at much higher rates, their civil rights and Black Power activism labeled as delusions.

In the early 1970s in the United States, the diagnostic model for schizophrenia was broad and clinically based using DSM II. Schizophrenia was diagnosed far more in the United States than in Europe, where the ICD-9 criteria were followed. The US model was criticised for failing to demarcate clearly those people with a mental illness. In 1980 DSM III was published and showed a shift in focus from the clinically based biopsychosocial model to a reason-based medical model. DSM IV brought an increased focus on an evidence-based medical model.

Historical treatment

Main article: History of schizophrenia § Development of treatments in the 20th century
A molecule of chlorpromazine, the first antipsychotic developed in the 1950s

In the 1930s a number of shock procedures which induced seizures (convulsions) or comas were used to treat schizophrenia. Insulin shock involved injecting large doses of insulin to induce comas, which in turn produced hypoglycemia and convulsions. The use of electricity to induce seizures was in use as electroconvulsive therapy (ECT) by 1938.

Carried out from the 1930s until the 1970s in the United States and until the 1980s in France, psychosurgery, including such modalities as the lobotomy, is recognized as a human rights abuse. In the mid-1950s, chlorpromazine, the first typical antipsychotic, was introduced, followed in the 1970s by clozapine, the first atypical antipsychotic.

Political abuse

Further information: Political abuse of psychiatry

From the 1960s until 1989, psychiatrists in the USSR and Eastern Bloc diagnosed thousands of people with sluggish schizophrenia, without signs of psychosis, based on "the assumption that symptoms would later appear". Now discredited, the diagnosis provided a convenient way to confine political dissidents.

Society and culture

See also: List of people with schizophrenia and Religion and schizophrenia

In the United States, the annual cost of schizophrenia – including direct costs (outpatient, inpatient, drugs, and long-term care) and non-healthcare costs (law enforcement, reduced workplace productivity, and unemployment) – was estimated at $62.7 billion for the year 2002. In the UK the cost in 2016 was put at £11.8 billion per year with a third of that figure directly attributable to the cost of hospital, social care and treatment.

Stigma

John Nash, an American mathematician and joint recipient of the 1994 Nobel Memorial Prize in Economic Sciences, had schizophrenia. His life was the subject of the 1998 book, A Beautiful Mind, by Sylvia Nasar.

In 2002, the term for schizophrenia in Japan was changed from seishin-bunretsu-byō (精神分裂病, lit. 'mind-split disease') to tōgō-shitchō-shō (統合失調症, lit. 'integration–dysregulation syndrome') to reduce stigma. The new name, also interpreted as "integration disorder", was inspired by the biopsychosocial model. A similar change was made in South Korea in 2012 to attunement disorder.

Cultural depictions

Media coverage, especially movies, reinforce the public perception of an association between schizophrenia and violence. A majority of movies have historically depicted characters with schizophrenia as criminal, dangerous, violent, unpredictable and homicidal, and depicted delusions and hallucinations as the main symptoms of schizophrenic characters, ignoring other common symptoms, furthering stereotypes of schizophrenia including the idea of a split personality.

The book A Beautiful Mind chronicled the life of John Forbes Nash who had been diagnosed with schizophrenia and won the Nobel Memorial Prize in Economic Sciences. The book was made into a film with the same name; an earlier documentary film was A Brilliant Madness.

In the UK, guidelines for reporting conditions and award campaigns have shown a reduction in negative reporting since 2013.

In 1964 a case study of three males diagnosed with schizophrenia who each had the delusional belief that they were Jesus Christ was published as The Three Christs of Ypsilanti; a film with the title Three Christs was released in 2020.

Research directions

See also: Animal models of schizophrenia

A 2015 Cochrane review found unclear evidence of benefit from brain stimulation techniques to treat the positive symptoms of schizophrenia, in particular auditory verbal hallucinations (AVHs). Most studies focus on transcranial direct-current stimulation (tDCM), and repetitive transcranial magnetic stimulation (rTMS). Techniques based on focused ultrasound for deep brain stimulation could provide insight for the treatment of AVHs.

The study of potential biomarkers that would help in diagnosis and treatment of schizophrenia is an active area of research as of 2020. Possible biomarkers include markers of inflammation, neuroimaging, brain-derived neurotrophic factor (BDNF), and speech analysis. Some markers such as C-reactive protein are useful in detecting levels of inflammation implicated in some psychiatric disorders but they are not disorder-specific. Other inflammatory cytokines are found to be elevated in first episode psychosis and acute relapse that are normalized after treatment with antipsychotics, and these may be considered as state markers. Deficits in sleep spindles in schizophrenia may serve as a marker of an impaired thalamocortical circuit, and a mechanism for memory impairment. MicroRNAs are highly influential in early neuronal development, and their disruption is implicated in several CNS disorders; circulating microRNAs (cimiRNAs) are found in body fluids such as blood and cerebrospinal fluid, and changes in their levels are seen to relate to changes in microRNA levels in specific regions of brain tissue. These studies suggest that cimiRNAs have the potential to be early and accurate biomarkers in a number of disorders including schizophrenia.

Ongoing fMRI research aims to identify biomarkers within these brain networks, potentially aiding in earlier diagnosis and better tracking of treatment responses in schizophrenia.

Explanatory notes

  1. A 2007 review stated that the 2002 estimate was still the best available, and a 2018 review cited the same $62.7 billion.

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