John Tierney reports on doctors who are revisiting the therapeutic effects of psilocybin, psychedelic compound. Excerpt:

The subjects’ reports mirrored so closely the accounts of religious mystical experiences, Dr. Griffiths said, that it seems likely the human brain is wired to undergo these “unitive” experiences, perhaps because of some evolutionary advantage.
“This feeling that we’re all in it together may have benefited communities by encouraging reciprocal generosity,” Dr. Griffiths said. “On the other hand, universal love isn’t always adaptive, either.”

More:

“There’s this coming together of science and spirituality,” said Rick Doblin, the executive director of MAPS. “We’re hoping that the mainstream and the psychedelic community can meet in the middle and avoid another culture war. Thanks to changes over the last 40 years in the social acceptance of the hospice movement and yoga and meditation, our culture is much more receptive now, and we’re showing that these drugs can provide benefits that current treatments can’t.”
Researchers are reporting preliminary success in using psilocybin to ease the anxiety of patients with terminal illnesses. Dr. Charles S. Grob, a psychiatrist who is involved in an experiment at U.C.L.A., describes it as “existential medicine” that helps dying people overcome fear, panic and depression.
“Under the influences of hallucinogens,” Dr. Grob writes, “individuals transcend their primary identification with their bodies and experience ego-free states before the time of their actual physical demise, and return with a new perspective and profound acceptance of the life constant: change.”

This brought to mind a guy I knew in college who was depressed and unreachable. He tried LSD one day for kicks, and reported a profound mystical experience, having to do with a new awareness of the unity of all things, and the power of a life force he identified as God filling all matter. His depression lifted after that, and he said he started to believe in God again because of his drug trip. He eventually converted to Catholicism.
Over the years, as I’ve read about varieties of mystical experience, I’ve thought about whether or not the temporary chemical changes psychedelic drugs bring about in our brains cause us to hallucinate things that aren’t there — clearly true in some cases — and whether or not they cause our brains to become more perceptive to realities that actually are there, but which can’t be perceived under normal circumstances. How would you tell the difference?
As I wrote the other day, Dr. Rex Jung has discovered evidence for a neurological link between mental illness and creativity. The connection between creative genius and madness has long been observed by non-scientists, and it is philosophically interesting to consider that our most visionary artists and religious geniuses see more deeply into the nature of life because their brains are abnormal, even dysfunctional in some sense. Similarly, psychedelic drugs are believed to work by affecting the production and uptake of serotonin in the brain — low levels of which are known to be associated with depression.
But antidepressant drugs that work on serotonin don’t cause the mystical experiences LSD users commonly report, nor do they produce the aesthetic experiences typical of hallucinogenic use (e.g., the intensification of sensory experiences, including synesthesia). So there’s something else going on here. Though the use of psychedelic drugs may open one up to more creative, spiritual and philosophical experiences, but it has been my experience being around people using psychedelics — including marijuana, a mild psychedelic — that (to put it charitably) they can’t articulate these experiences very well.
I am still left with big questions about all this. First (and to repeat), do psychedelic drugs actually open up a door of perception into dimensions of reality that are closed to our brains under normal conditions, or do they only cause hallucinations? (And how would you know the difference?). Second, given the commonplace testimony from psychedelic drug users to experiences that closely resemble mystical episodes of insight that saints and spiritual geniuses in various religious traditions have had, is it advisable for people in search of enlightenment to assist their quest with hallucinogenic drugs? Why or why not?
(On that last question, my intuition is that it would be the difference between someone making a million dollars through years of hard, disciplined labor, and someone winning the lottery. The money is the same, but the lottery winner has no context in which to place his bounty, and, as studies have shown, is far more likely to have his life ruined by the gift. That said, if medical research can show that using hallucinogenics can help terminally ill or badly depressed people find a sense of purpose, positive meaning or peace with their condition, why on earth would anyone want to deny them that?)