LSD, PCP, and Other Hallucinogens

In the early 1940s, a researcher working for the Sandoz pharmaceutical company stumbled upon the mind-altering qualities of LSD following an accidental ingestion. Sandoz has marketed a number of ergot derivatives, which have long had a place in medical use because they are effective in aborting migraine headaches. But this new compound had surprisingly profound effects unlike those seen with the migraine drugs.

Scientists began to study the effects of the drug, looking for a potential application in medicine.

Psychiatrists studied the drug’s potential use as a chemical that could enhance exploratory types of psychotherapy. At that time, treatment in psychiatry was based on the theory that psychoanalytic exploration of the unconscious would lead to the resolution of buried conflicts, which would result in the relief of symptoms. If a compound such as LSD could facilitate this process by loosening repression and bringing unconscious material to the fore, then it might be very useful.

LSD was used experimentally over the next two decades in a number of medical and military settings with some encouraging positive results, but there were also reports of serious adverse reactions such as suicides and psychosis. The eventual conclusion about LSD as a psychiatric drug was that, while interesting in its effects, it was not terribly useful and was potentially dangerous.

The rise in the popularity and street use of LSD was a phenomenon that reflected the cultural changes of the 1960s.

Dr. Timothy Leary, once an instructor at Harvard, was instrumental in popularizing the drug, and coined the term “psychedelic.” Marijuana and LSD became popular symbols of the antiestablishment movement. The more the government objected to and preached against these drugs, the more popular they became. LSD lost much of its attractiveness after publicity about “bad trips” and about people doing dangerous things while under its influence, such as leaping from rooftops to their death because they thought they could fly. The use of LSD waned through the seventies and eighties, as the use of the combined hallucinogen/stimulant known as Ecstasy increased, but in the late nineties LSD made a comeback among teenagers and young adults.

Originally developed in the 1950s, PCP, or phencyclidine, is a dissociative anesthetic, which means that it causes a patient undergoing surgery to be oblivious of physical pain. Because of problems with severe behavioral reactions to PCP, it was restricted to veterinary use. But it is easily manufactured in illegal laboratories, which is the main source of street supplies.

PCP is included in the section on hallucinogens because its effects include distortions in perception and judgment, but it differs from the other hallucinogens in some respects. Laboratory animals demonstrate that PCP is highly reinforcing and therefore highly addictive. PCP causes a psychotic state that can persist for prolonged periods of time and is indistinguishable clinically from schizophrenia. It also causes agitation and aggressive behavior, sometimes to an extreme degree.

PCP is known on the street as “angel dust” and is sometimes sold to unsuspecting users as THC (the active ingredient in marijuana) or is laced into poor-quality marijuana to increase its street value.

Addiction to PCP resembles crack addiction. Addicts use it in runs that may last for days, and then they crash. The drug causes profound stimulation of the brain and can cause nystagmus (rhythmic jerking movements of the eye), muscular rigidity, and seizures, as well as high fevers, sharp increases in blood pressure, and destruction of muscle tissue.

There are a number of other hallucinogens with differing properties and durations of action. The indole-type hallucinogens have chemical structures resembling the neurotransmitter serotonin, and are so named because they contain a chemical component known as an indole ring. They include the ergot alkaloids. LSD, DMT, and psilocybin (found in some mushrooms) are indole-type hallucinogens. The phenylethyamines resemble the neurotransmitter norepinephrine and have stimulant qualities. Mescaline, DOM, MDA, and MDMA are phenylethylamine-type hallucinogens. MDA and MDMA belong to the class called “designer drugs,” since they were specifically designed by chemists to have hallucinogenic properties. Illicit labs have produced many chemical variations of MDA and MDMA, which are untested and unsafe but often sold on the street with the Ecstasy label.

Like LSD, MDMA was studied extensively for possible uses in the field of psychiatry. The discovery that both MDA and MDMA have toxic actions on brain cells has limited their potential for legitimate use. These drugs have been shown to kill brain cells that produce serotonin. The long-term effect on users is not yet known, but it’s feared that abnormalities in the serotoninergic systems of the brain will emerge over time in former users of these drugs. Since serotonin is important in the processing and control of emotions, these effects could be profound.

Hallucinogens cause changes in perception and cognition, with effects differing slightly among the different ones. The stimulant hallucinogens have additional effects similar to those of amphetamines. The addictiveness of the hallucinogens also varies. MDA and MDMA have been shown to cause laboratory animals to self-administer the drug, but pure LSD does not possess this quality. This indicates that MDA and MDMA interact in a reinforcing fashion in the pleasure center of the brain, as do drugs like amphetamines, cocaine, alcohol, and opiates.

The addictive use of hallucinogens alone is occasionally seen, but it occurs most commonly in people with multiple drug dependencies, who will use anything available to alter mood. People recovering from the abuse of hallucinogens sometimes experience flashbacks, or sudden hallucinatory experiences that mimic the effect of the drug. The cause of flashbacks is unclear. They can occur months to years after the drug is out of the system but usually fade with time.

Elizabeth Connell Henderson, M.D.


Appendix A: Regulation of Addictive Substances

Appendix B: Sources of Additional Information

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