Types of Hallucinogenic Drugs

Hallucinogenic drugs form a broad category that shares one similarity: they all produce hallucinations to some varying degree.  A quick perusal of the web will show that it is hard to break down the category into specific types because of the different definitions that can be applied.   It is possible to categorize them by molecular type, method of synthesis, and hallucinogenic effects, among many possibilities.

Arguably the best categorization of hallucinogenic drugs is by the effect they have on the human mind.  There are three possible categories:  psychedelics, dissociatives, and deliriants.[1]   Psychedelics are any drugs which alter one's perception.  These drugs are often used to “expand the mind” and explore one's deeper consciousness.  Drugs in this category include LSD (lysergic acid diethylamine), mescaline, and some mushrooms.  It is believed that these drugs work by binding to receptors in the brain called 5-HT2 receptors.  These are the same receptors used by the brain chemical seratonin, which is a neurotransmitter believed to be inportant in the regulation of mood, among other things.  These drugs are also most active in two regions of the brain:  the cerebral cortex, which is responsible for perception and mood, and the locus ceruleus, which has been described as the brain's “novelty detector.”[2]

Another category of hallucinogens is dissociative drugs.  As the name suggests, these drugs cause the user to have feelings of detachment or dissociation from reality.  Examples of drugs in this class include PCP (phencyclidine) and ketamine, and in high enough dosages, dextromethorphan (the ingredient found in some cough syrups).  This class of drugs is known to work by changing the amount of the neurotransmitter glutamate in the brain.  Glutamate is one of the neurotransmitters associated with the perception of pain and environmental awareness.[3]

The third category of hallucinogens is deliriant drugs.  These drugs induce delirium in the user.  Delirium is defined as “a mental disturbance marked by disorientation and confused thinking in which the patient incorrectly comprehends his surroundings. The delirious person is drowsy, restless, and fearful of imaginary disasters. “[4]  Deliriants work by reducing the effects of the neurotransmitter acetylcholine, which is responsible for mood stability.[5]  Some of the more common drugs in this family include several plant-related compounds including deadly nightshade and mandrake, as well as diphenhydramine (Benedryl) in high enough dosages.[6]

All hallucinogens work by interfering with the normal operation of the brain's neurotransmitters.  This interference causes the brain to work abnormally and in this case to produce hallucinations of varying degrees.  Many studies into possible therapeutic uses of hallucinogens have been done, with widely divergent results.  In some cases, legitimate uses for some drugs with hallucinogenic properties (drugs such as dextromethorphan and benedryl) have been found, while in other cases drugs such as LSD and PCP have been removed from the list of therapeutic drugs.

1:    Psychedelics, dissociatives and deliriants.  http://en.wikipedia.org/wiki/Hallucinogen
2:    National Institute on Drug Abuse, “Hallucinogens and Dissociative Drugs,” http://www.drugabuse.gov/PDF/RRHalluc.pdf, pg 3
3:    ibid., pg 2
4:    Encyclopedia Brittanica, “Delirium”, http://www.britannica.com/eb/article-9029832/delirium
5:    “Borderline Personality Disorder”, http://bpd.about.com/od/bpdglossary/g/Acetylcholine.htm
6:    http://en.wikipedia.org/wiki/Hallucinogen