Chapter 14: Hallucinogens

Psychoactive plants that alter perceptions have been important for recreation, in medicine and in the development of spiritual and religious traditions.  For thousands of years, humans have taken advantage of these psychoactive plants, and more recently, the active compounds have been isolated and new drugs have been created in the laboratory.  Hallucinogens are drugs that produce profound alterations in perception, including unusual visual sensations and often changes in the perception of one's own body.

Hallucinogens can be classified in a number of ways.  One major group is the phantastica, which alter perception while allowing the user to remain in communication with the present world.  Phantastica include the indole hallucinogens, which share the indole chemical structure found in the neurotransmitter serotonin; and the catechol hallucinogens, which share the catechol structure found in norepinephrine and dopamine.

Chief among the indole hallucinogens is LSD, an odorless, colorless, synthetic drug that is one of the most potent psychochemicals known.  It is usually taken orally and absorbed rapidly through the gastrointestinal tract.  It modifies perceptions so that users see bright and intense colors, have an altered sense of time and body image, and experience synesthesia, in which the senses become mixed so that, for example, sounds may appear as visual images.  LSD also enhances emotionality, so that the real world is seen differently and is responded to with great emotion.  The LSD trip is a unique and variable experience: users may feel they are uncovering great secrets or profundities or they may experience paranoia and feelings of persecution.  Some users may also experience panic reactions or flashbacks.

Other chemicals that contain the indole nucleus have effects similar to LSD.  These include psilocybin, which comes from certain kinds of Mexican mushrooms, the seeds from the morning glory and the Hawaiian baby woodrose. DMT is an indole hallucinogen found in many plants that is sometimes combined with a vine to make a concoction called ayahuasca.

Mescaline, from the peyote cactus, is a key catechol hallucinogen.  Peyote has a long pre-Columbian history of use among Mexican Indians.  When sliced and dried, the so-called buttons remain psychoactive indefinitely.  In high doses, mescaline has psychological effects quite similar to those of indole hallucinogens. Amphetamine derivatives like DOM, MDA, and MDMA have few stimulant effects and act much more like mescaline; they are also classified as catechol hallucinogens.  MDMA, also known as Ecstasy, promotes empathy and closeness with others, but there is some evidence that it is capable of producing permanent brain damage in users.

Deliriants are a second major group of hallucinogens.  Compared to the phantastica, the deliriants have more of a tendency to produce mental confusion and a loss of touch with reality.  PCP, or angel dust, produces more changes in body perception and fewer visual effects than LSD.  It causes a dissociated state that resembles schizophrenia and may include aggression and mania.  Ketamine and other deliriants similar to PCP cause different degrees of depressant and dissociative effects.

Anticholinergic hallucinogens are found in many plants throughout the world and have been used not only recreationally, medically, and spiritually but also as poisons.  Plants containing anticholinergics include belladonna, mandrake, henbane, and Datura.  The Amanita mushroom can cause severe effects of intoxication and is also highly toxic.