Hallucinogenic compounds in the form of, or extracted from, plants and
mushrooms have been used for centuries, mostly in religious rituals.
Almost all hallucinogens contain nitrogen and are classified as
alkaloids. Many hallucinogens have chemical structures similar to those
of neurotransmitters (e.g., acetylcholine-, serotonin-, or
catecholamine-like) and temporarily interfere with their action or bind
their receptor sites, but the exact mechanisms by which these
substances exert their hallucinogenic effects remain unclear. This
InfoFacts will discuss four common types of hallucinogens:
- LSD (d-lysergic acid diethylamide) is one of the most
potent mood-changing chemicals. It was discovered in 1938 and is
manufactured from lysergic acid, which is found in ergot, a fungus that
grows on rye and other grains.
- Peyote is a small,
spineless cactus in which the principal active ingredient is mescaline.
This plant has been used by natives in northern Mexico and the
southwestern United States as a part of their religious rites.
Mescaline can also be produced through chemical synthesis.
- Psilocybin
(4-phosphoryloxy-N,N-dimethyltryptamine) is obtained from certain types
of “magic” mushrooms that are indigenous to tropical and subtropical
regions of South America, Mexico, and the United States. These
mushrooms typically contain less than 0.5 percent psilocybin plus trace
amounts of psilocin, another hallucinogenic substance.
- PCP
(phencyclidine) was developed in the 1950s as an intravenous
anesthetic, but this use has been discontinued due to serious adverse
effects.
How are Hallucinogens Abused?
The very same characteristics that led to the incorporation of
hallucinogens into ritualistic or spiritual traditions have also led to
their propagation as drugs of abuse. Importantly, and unlike most other
drugs, the effects of hallucinogens are highly variable and
characteristically unreliable, producing different effects in different
people or at different times. This is mainly due to the significant
variations in amount and composition of active compounds, particularly
in the hallucinogens derived from plants and mushrooms. Because of
their unpredictable nature, the use of hallucinogens can be
particularly dangerous.
- LSD is sold in tablets, capsules, and, occasionally,
liquid form; thus, it is usually taken orally. LSD is often added to
absorbent paper, which is then divided into decorated pieces, each
equivalent to one dose. The experiences, often referred to as “trips,”
are long; typically, they begin to clear after about 12 hours.
- Peyote.
The top of the peyote cactus—also referred to as the crown—consists of
disc-shaped buttons that are cut from the roots and dried. These
buttons are generally chewed or soaked in water to produce an
intoxicating liquid. The hallucinogenic dose of mescaline is about 0.3
to 0.5 grams, and its effects last about 12 hours. Because the extract
is so bitter, some prefer to prepare a tea by boiling the cacti for
several hours.
- Psilocybin. Mushrooms containing
psilocybin are available fresh or dried and are typically taken orally.
The active psilocin (4-hydroxy-N,N-dimethyltryptamine) and psilocybin
(4-phosphoryloxy-N,N-dimethyltryptamine) cannot be inactivated by
cooking or freezing preparations. Thus, they may also be brewed as a
tea or added to other foods to mask their bitter flavor. The effects of
psilocybin, which appear within 20 minutes of ingestion, last
approximately 6 hours.
- PCP is a white crystalline
powder that is readily soluble in water or alcohol. It has a
distinctive bitter chemical taste. PCP can be mixed easily with dyes
and turns up on the illicit drug market in a variety of tablets,
capsules, and colored powders. It is normally snorted, smoked, or
ingested. For smoking, PCP is often applied to a leafy material such as
mint, parsley, oregano, or marijuana. Depending upon how much and by
what route PCP is taken, its effects can last approximately 4–6 hours.
How do Hallucinogens Affect the Brain?
LSD, peyote, psilocybin, and PCP are drugs that cause hallucinations,
which are profound distortions in a person’s perception of reality.
Under the influence of hallucinogens, people see images, hear sounds,
and feel sensations that seem real but do not exist. Some hallucinogens
also produce rapid, intense emotional swings. LSD, peyote, and
psilocybin cause their effects by initially disrupting the interaction
of nerve cells and the neurotransmitter serotonin.1 Distributed
throughout the brain and spinal cord, the serotonin system is involved
in the control of behavioral, perceptual, and regulatory systems,
including mood, hunger, body temperature, sexual behavior, muscle
control, and sensory perception. PCP, on the other hand, acts mainly
through a type of glutamate receptor in the brain, important for the
perception of pain, responses to the environment, and memory.
There have been no properly controlled research studies on the
specific effects of these drugs on the human brain, but smaller studies
and several case reports have been published documenting some of the
effects associated with the use of hallucinogens:
- LSD. Sensations and feelings change much more
dramatically than the physical signs. The user may feel several
different emotions at once or swing rapidly from one emotion to
another. If taken in large enough doses, the drug produces delusions
and visual hallucinations. The user’s sense of time and self is
altered. Experiences may seem to “cross over” different senses, giving
the user the feeling of hearing colors and seeing sounds. These changes
can be frightening and can cause panic. Some LSD users experience
severe, terrifying thoughts and feelings of despair, fear of losing
control, or fear of insanity and death while using LSD.
- LSD
users can also experience flashbacks, or recurrences of certain aspects
of the drug experience. Flashbacks occur suddenly, often without
warning, and may occur within a few days or more than a year after LSD
use. In some individuals, the flashbacks can persist and cause
significant distress or impairment in social or occupational
functioning, a condition known as hallucinogen-induced persisting
perceptual disorder (HPPD).
Most users of LSD voluntarily decrease
or stop its use over time. LSD is not considered an addictive drug
since it does not produce compulsive drug-seeking behavior. However,
LSD does produce tolerance, so some users who take the drug repeatedly
must take progressively higher doses to achieve the state of
intoxication that they had previously achieved. This is an extremely
dangerous practice, given the unpredictability of the drug. In
addition, cross-tolerance between LSD and other hallucinogens has been
reported.
Peyote. The long-term residual psychological and cognitive effects of
mescaline, peyote’s principal active ingredient, remain poorly
understood. A recent study found no evidence of psychological or
cognitive deficits among Native Americans that use peyote regularly in
a religious setting.2 It should be mentioned, however, that these
findings may not generalize to those who repeatedly abuse the drug for
recreational purposes. Peyote abusers may also experience flashbacks.
- Psilocybin.
The active compounds in “magic” mushrooms have LSD-like properties and
produce alterations of autonomic function, motor reflexes, behavior,
and perception.3 The psychological consequences of psilocybin use
include hallucinations, an altered perception of time, and an inability
to discern fantasy from reality. Panic reactions and psychosis also may
occur, particularly if a user ingests a large dose. Long-term effects
such as flashbacks, risk of psychiatric illness, impaired memory, and
tolerance have all been described in case reports.
- PCP.
The use of PCP as an approved anesthetic in humans was discontinued in
1965 because patients often became agitated, delusional, and irrational
while recovering from its anesthetic effects. PCP is a “dissociative
drug,” meaning that it distorts perceptions of sight and sound and
produces feelings of detachment (dissociation) from the environment and
self. First introduced as a street drug in the 1960s, PCP quickly
gained a reputation as a drug that could cause bad reactions and was
not worth the risk. However, some abusers are attracted by feelings of
strength, power, and invulnerability as well as a numbing effect on the
mind that PCP can induce. Among the adverse psychological effects
reported are:
- Symptoms that mimic schizophrenia,
such as delusions, hallucinations, paranoia, disordered thinking, and a
sensation of distance from one’s environment.
- Mood
disturbances: For example, approximately 50 percent of individuals
presenting for drug-induced problems in an emergency room setting and
meeting criteria for PCP use in the past 48 hours reported significant
elevations in anxiety symptoms.
- People who abuse
PCP for long periods of time report memory loss, difficulties with
speech and thinking, depression, and weight loss. These symptoms can
persist up to a year after stopping PCP abuse.
- Addiction:
PCP is addictive—its repeated abuse can lead to craving and compulsive
PCP-seeking behavior, despite severe adverse consequences.