Re: How does LSD affect the brain?

Dear Andrew,

The mechanism or mechanisms of action of LSD have been under study for over three decades. While some progress has been made, it is not known how LSD or other similar drugs produce their so-called "psychedelic" effects. The chemical structure of LSD somewhat resembles the structure of the naturally occurring neurotransmitter serotonin. Thus, it appears that the effects of LSD are probably mediated by its effects on receptors for serotonin in the central nervous system. It may also affect other neurotransmitter systems, such as the dopamine, norepinephrine, and acetylcholine systems.

LSD is not stored in the spinal cord or anywhere else in the body. After a day or two, it has all been broken down and excreted. Thus "flashbacks," the re-experiencing of LSD-like effects weeks, months or years after exposure to the drug, is not due to residual LSD in the body. The mechanism of flashbacks is not known but is probably similar to the flashbacks experienced by people who have been through traumatic events, such as war veterans, rape victims, etc. These people can have very vivid memories of their past traumas, either with or without full-blown post-traumatic stress disorder. As for the damaging effects of LSD, there is no good evidence for things like chromosome damage or actual organic brain damage. However, there is no doubt that it is potentially a very dangerous drug. It has clearly precipitated both temporary and permanent psychosis. It is impossible to determine if the people who were affected in this way had some "predisposition" or if they would never have experienced any psychiatric symptoms of any kind if they had not been exposed to LSD. But it is certainly possible that in some individuals, a period of heavy LSD use is the sole reason why they suffer severe mental illness.

Other adverse events, such as suicide and suicide attempts and accidents, occur with LSD as well. And although the drug is still relatively popular among young people, it is without a doubt far more dangerous than, for example, marijuana.

The books and scientific articles that have been written about LSD are almost too numerous to count. If you are interested in finding out more about this drug, I strongly recommend that you use a scientific source such as MEDLINE or the books in a university library rather than what you find on the World Wide Web. The information on the Web is likely to be filled with inaccuracies and biases, both pro and con.

Finally, it is my strong advice to you that you not take chances by "trying" LSD. For one thing, buying or possessing LSD is illegal and you could end up spending years in prison. For another thing, what someone tells you is LSD might in fact be something totally different. And of course, even if you don't get caught and you obtain the real thing, you may find that it causes depression, severe anxiety, or even a schizophrenic-like break from reality. While this would almost certainly not be permanent following one exposure to the drug, it is definitely not something one wants to experience, even briefly. So even though it sounds trite, my advice to you on the subject of LSD is "just say no."

Sincerely,
Joe Simpson
Neuroscience Moderator
MD/PhD Student, Neurosciences
School of Medicine