Hallucinogens and related disorders

Definition

Hallucinogens are a chemically diverse group of drugs that cause changes in a person's thought processes, perceptions of the physical world, and sense of time passing. Hallucinogens can be found naturally in some plants, and can be synthesized in the laboratory. Most hallucinogens are abused as recreational drugs. Hallucinogens are also called psychedelic drugs.

Description

Hallucinogens are as old as civilization. Many cultures recorded eating certain plants specifically to induce visions or alter the perception of reality. Often these hallucinationswere part of a religious or prophetic experience. Shamans in Siberia were known to eat the hallucinogenic mushroom Amanita muscaria. The ancient Greeks and the Vikings also used naturally occurring plant hallucinogens. Peyote, a spineless cactus native to the southwestern United States and Mexico was used by native peoples, including the Aztecs, to produce visions.

Although several hundred plants are known to contain compounds that cause hallucinations, most hallucinogens are synthesized in illegal laboratories for delivery as street drugs. The best known hallucinogens are lysergic acid diethylamide (LSD), mescaline, psilocybin, and MDMA (ecstasy). Phencyclidine (PCP, angel dust) can produce hallucinations, as can amphetaminesand marijuana, but these drugs are not considered classic hallucinogens and are discussed under separate entries. In addition, new designer drugs that are chemical variants of classic hallucinogens are apt to appear on the street at any time.

Although hallucinogens produce similar physical and psychological effects, they are a diverse group of compounds. However, all hallucinogens appear to affect the brainin similar ways. Although the mechanism of action of hallucinogens is not completely understood, researchers have shown that these drugs bind with one type of serotonin receptor (5-HT2) in the brain.

Serotonin is a neurotransmitter that facilitates transmission of nerve impulses in the brain and is associated with feelings of well-being, as well as many physiological responses. When a hallucinogenic compound binds with serotonin receptors, serotonin is blocked from those receptor sites, and nerve transmission is altered. There is an increase in free (unbound) serotonin in the brain. The result is a distortion of the senses of sight, sound, and touch, disorientation in time and space, and alterations of mood. In the case of hallucinogen intoxication, however, a person is not normally delirious, unconscious, or dissociated. He or she is aware that these changes in perception are caused by the hallucinogen.


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