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Psychoactive drug

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A psychoactive drug or psychotropic substance is a chemical that alters brain function, resulting in temporary changes in perception, mood, consciousness, or behaviour. Such drugs are often used for recreational and spiritual purposes, as well as in medicine, especially for treating neurological and psychological illnesses.

Many of these substances (especially the stimulants and depressants) can be habit forming, and lead to abuse. Conversely, others (namely the psychedelics) can help to treat and even cure such addictions.

An assortment of psychoactive drugs

A brief history of drug use

Drug use is not a new phenomenon by any means. There is archaeological evidence of the use of psychoactive substances dating back at least 10,000 years, and historical evidence of cultural use over the past 5,000 years.

While medicinal use plays a very large role, it has been suggested that the urge to alter one's consciousness is as primary as the drive to satiate thirst, hunger or sexual desire.

Some may point a finger to marketing, availability or the pressures of modern life as to why we are such a pill-popping, coffee-swilling, beer-guzzling society, but one only has to look back at history, or even to children with their desire for spinning, swinging, sliding amongst other activities to see that the drive to alter one's state of mind is universal.

This relationship is not limited to humans. A surprising number of animals consume different psychoactive plants and animals, berries and even fermented fruit, clearly becoming intoxicated. Traditional legends of sacred plants often contain references to animals that introduced man to their use.

Biology suggests an evolutionary connection between psychoactive plants and animals, as to why these chemicals and their receptors exist within the nervous system.

Other psychoactive drugs

Ways psychoactive drugs affect the brain

There are many ways in which psychoactive drugs can affect the brain. While some drugs affect neurons presynaptically, others act postsynaptically and some drugs don't even attack the synapse, working on neural axons instead. Here is a general breakdown of the ways psychoactive drugs can work.

  1. Prevent The Action Potential From Starting
    • Lidocaine, TTX (they bind to voltage-gated sodium channels, so no action potential begins even when a generator potential passes threshold)
  2. Neurotransmitter Synthesis
    • Increase - L-Dopa, tryptophan, choline (precursors)
    • Decrease - PCPA (inhibits synthesis of 5HT)
    • Causes increased sensitivity to the five senses, due to an increasing number of signals being sent to the brain.
  3. Neurotransmitter Packaging
    • Increase - MAO Inhibitors
    • Decreasing - Resperine (pokes holes in the synaptic vesicles of catecholamines)
  4. Neurotransmitter Release
    • Increase - Black Widow Spider (Ach)
    • Decrease - Botulinum Toxin (Ach), Tetanus (GABA)
  5. Agonists - Mimic the original NTs and activate the receptors
    • Muscuraine, Nicotine (Ach)
    • AMDA, NMDA (Glu)
    • Alcohol, Benzodiazepines (GABA)
  6. Antagonists - Bind to the receptor sites and block activation
    • Atropine, Curare (Ach)
    • PCP (Glu)
  7. Prevent Ach Breakdown -
    • Insecticides, Nerve Gas
  8. Prevent Reuptake
    • Cocaine (DA), Amphetamines (E)
    • Tricyclics, SSRIs

- based on information taught in NSC 201, Vanderbilt University

See also

Category: