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Emil Kraepelin (February 15 1856–October 7 1926) was a German psychiatrist who attempted to create a synthesis of the hundreds of mental disorders classified by the 19th century, grouping diseases together based on classification of common patterns of symptoms, rather than by simple similarity of major symptoms in the manner of his predecessors. In fact, it was precisely because of the demonstrated inadequacy of such methods that Kraepelin developed his new diagnostic system.

In 1886, after only eight years of training, he was appointed to a professorship at the University of Tartu (then Dorpat) in what is today Estonia and became the director of an eighty-bed University Clinic. There he was able to study and record many clinical histories in detail and "was led to consider the importance of the course of the illness with regard to the classification of mental disorders." Ten years later he announced that he had found a new way of looking at mental illness. He referred to the traditional view as "symptomatic" and to his view as "clinical".

Drawing on his long term research, and using the criteria of course, outcome and prognosis, he developed the concept of dementia praecox, which he defined as the "sub-acute development of a peculiar simple condition of mental weakness occurring at a youthful age." When he first introduced this concept as a diagnostic entity in the fourth German edition of his Lehrbuch der Psychiatrie in 1893, it was placed among the degenerative disorders alongside, but separate from, catatonia and dementia paranoides. At that time the concept corresponded by and large with Ewald Hecker's hebephrenia. In the sixth edition of the Lehrbuch in 1899 all three of these clinical types are treated as different expressions of one disease, dementia praecox.

Kraepelin postulated that there is a specific brain or other biological pathology underlying each of the major psychiatric disorders. Just as his laboratory discovered the pathologic basis of what is now known as Alzheimer's disease, Kraepelin was confident that it would someday be possible to identify the pathologic basis of each of the major psychiatric disorders. This was in keeping with the prevailing scientific materialism of his day, which is now seen as reductionistic.

One of the cardinal principles of his method was the claim that any given symptom may appear in virtually any one of these disorders; i.e. there is virtually no single symptom occurring in dementia praecox (the name was later changed to "schizophrenia" by Eugen Bleuler), which cannot sometimes be found in manic-depression. According to Kraepelin, what distinguishes each disease symptomatically (as opposed to the underlying pathology) is not any particular (pathognomonic) symptom or symptoms, but a specific pattern of symptoms. In the absence of a direct physiological or genetic test or marker for each disease, it is, Kraepelin claimed, only possible to distinguish them by their specific pattern of symptoms. Thus, Kraepelin's system is a method for pattern recognition, not grouping by common symptoms. Notably, however, his immediate successors, notably Swiss reformer Bleuler successfully challenged Kraepelin's alleged 'pattern' underlying 'dementia praecox' at the earliest opportunity.

Kraepelin also claimed to demonstrate specific patterns in the genetics of these disorders and specific and characteristic patterns in their course and outcome. For example, that there tend to be more schizophrenics among the relatives of schizophrenic patients than in the general population, while manic-depression is more frequent in the relatives of manic-depressives . - but clearly there is something circular about this - the 'great diagnostician' had allowed himself free rein to create the very database to confirm his own theories.

He also reported a pattern to the course and outcome of these conditions. Kraepelin believed that dementia praecox had a deteriorating course in which mental function continuously (although perhaps erratically) declines, while manic-depressive patients experienced a course of illness which was intermittent, where patients were relatively symptom-free during the intervals which separate acute episodes. This led Kraepelin to name what we now know as schizophrenia, dementia praecox (the dementia part signifing the irreversible mental decline). It later became clear that dementia praecox did not necessarily lead to mental decline, nor did it occur only in the young, and so was renamed by Eugene Bleuler to correct the misnomer - an effective broadside against the German's whole methodology and regressive influence.

Kraepelin is credited with the classification of what was previously considered to be a unitary concept of psychosis, into two distinct forms:

• Manic Depression (now seen as comprising a range of mood disorders such as Major Depression and Bipolar Disorder), and
• Dementia praecox, which was later renamed schizophrenia by Eugene Bleuler.

Kraepelin was also a colleague of Alois Alzheimer, and co-discoverer with Alzheimer of Alzheimer's disease.

In addition to his distinction between dementia praecox and manic-depression, Kraepelin should be credited with being the founder of modern scientific psychiatry, psychopharmacology and psychiatric genetics, according to the eminent psychologist H. J. Eysenck in his Encyclopedia of Psychology. Kraepelin postulated that psychiatric diseases are principally caused by biological and genetic disorders. His psychiatric theories dominated the field of psychiatry throughout the twentieth century, but are now being questioned. He vigorously opposed the approach of Freud who regarded and treated psychiatric disorders as caused by psychological factors.

Kraepelin's basic concepts however still dominate psychiatric research and academic and applied psychiatry, and today the published literature in the field of psychiatry is disproportionately biological and genetic in its orientation. Kraepelin's 'great contribution' in distinguishing 'dementia praecox' and manic depression remains relatively unknown to the general public and his work is little read. This is despite the recent widespread adoption of his fundamental theories on the etiology and diagnosis of psychiatric disorders, which form the basis of all major diagnostic systems in use today, especially the American Psychiatric Association's DSM-IV and the World Health Organization's ICD system.

Kraepelin, while arguably succeeding in raising the profile and status of psychiatric science, abused his status as a natural scientist to introduce unscientific, circular theories of a kind endemic in his day into a vulnerable young science still suffering, to this day, from his influence at least as much as benefiting by it. He can be said to have prepared the way for Hitler's Final Solution in his clinical stigmatisation of the mentally ill.

External links

• Extensive bibliography of English translations of Kraepelin's works
• Extensive bibliography of works by and about Kraepelin's including those in the original German

See

• and

for biographies of Kraepelin.

• International Kraepelin Society contact

• 1856 births
• 1926 deaths
• German psychiatrists
• German neuroscientists
• Psychosis