lysergic acid diethylamide

Lysergic acid diethylamide (LSD) is a synthetic tryptamine whose action at serotonin receptors helped open a path from psychedelic chemistry toward modern neuroscience. The book follows that path from molecular resemblance and neurochemical research to proposals for easing the fear of death and treating alcohol misuse, while emphasizing that identifying a receptor does not explain the full content of a psychedelic experience.

Chemical Identity and Neural Action

LSD belongs to the tryptamine family, along with psilocin and 5-MeO-DMT. Tryptamines are organic compounds distinguished by an indole structure of two linked rings, one containing six atoms and the other five. They occur widely in plants, fungi, and animals, where they commonly act as signaling molecules between cells. Serotonin, whose chemical name is 5-hydroxytryptamine, is the best-known tryptamine in the human body. The resemblance between serotonin and psychedelic molecules is not merely visual: it helps explain how these compounds can interact with the brain’s serotonin system.

Serotonin binds to many receptor types distributed throughout the brain and body, including the digestive tract. What it does depends on the receptor and its location; it can excite a neuron in one context and inhibit it in another. Classical psychedelics have a strong affinity for the 5-HT2A receptor, which is especially numerous in the cortex, the brain’s outermost and evolutionarily most recent layer. LSD resembles serotonin closely enough to bind at this receptor and activate it. Its affinity is stronger still: LSD is described as “stickier” at 5-HT2A than serotonin itself.

That chemical comparison prompted speculation about whether the body might produce a more specialized substance for activating the receptor, perhaps under particular conditions such as dreaming. DMT was suggested as one candidate because trace amounts had been found in the pineal glands of rats. This was a hypothesis, not evidence that LSD itself is naturally produced in the body. The distinction matters: the account links LSD to a larger question about endogenous chemistry without treating the speculation as settled fact.

From Neurochemistry to the Brain

The study of serotonin and LSD became closely intertwined in the 1950s. LSD’s ability to affect consciousness at extraordinarily small doses helped advance the developing field of neurochemistry, work that contributed to the later development of SSRI antidepressants. Yet a molecular account of LSD’s action remained only a beginning: receptor binding could not by itself explain the character of an experience or the persistence of its effects after the drug had left the body.

In 1998, Swiss researcher Franz Vollenweider demonstrated that LSD and psilocybin act on the human brain by binding to 5-HT2A receptors. He first gave participants ketanserin, a drug that blocks the receptor, and then administered psilocybin. With the receptor blocked, nothing happened. The experiment offered a concrete link between a particular receptor and psychedelic action, but it did not resolve how that action might lead to a dissolution of the ego or a collapse of the distinction between subject and object. In the book’s account, LSD’s chemistry illuminates a route into altered consciousness without reducing consciousness to a single receptor event.

LSD and the Fear of Dying

The proposal to give psychedelics to people who were dying originated with Aldous Huxley, who wrote to Humphry Osmond suggesting research into LSD for terminal cancer patients. Huxley hoped it might make dying a more spiritual and less strictly physiological process. He later received an LSD injection from his wife, Laura, on his deathbed on November 22, 1963. His proposal thus joined a research question to a personal, final use of the drug.

By 1965, the idea had been explored with cancer patients in North America. In an essay for Harper’s, psychiatrist Sidney Cohen considered psychedelics’ potential to alter the experience of dying and described the approach as “therapy by self-transcendence.” Its premise was that fear of death could be intensified by the ego’s sense of separateness, particularly when illness made the body’s decline unavoidable. The proposed therapeutic aim was not simply to suppress fear, but to offer a brief experience in which a person could discover that the usual boundaries of the self were not indispensable.

Cohen quoted a woman dying of ovarian cancer who described feeling detached from herself, her pain, and her physical decline after an LSD session. She regarded her extinction as less momentous than it had seemed before, while making clear that she neither welcomed death nor tried to postpone it. Her account gives the therapeutic claim its human scale: LSD was being considered as a means of changing a patient’s relation to dying, not as a cure for the cancer or a guarantee of spiritual certainty.

Alcohol Treatment and the Evidence

The use of psychedelics to treat addiction had a longer history than the mid-century clinical experiments. Native Americans had used peyote as both a sacrament and a treatment for alcoholism, which had afflicted Indigenous communities since the arrival of white settlers. In the 1950s and 1960s, thousands of people with alcoholism were treated with LSD and other psychedelics. For a period, the therapy was accepted as a standard treatment in Saskatchewan.

The clinical record was uneven. Reports could be enthusiastic, but many formal studies were poorly designed or lacked adequate controls. Outcomes also varied with the investigators and the treatment conditions: results tended to look stronger in the hands of sympathetic therapists, especially those who had taken LSD themselves, and weaker when inexperienced researchers administered very large doses without attention to the patient’s set and setting. This variation made it difficult to distinguish the drug’s effects from the expectations, preparation, and circumstances surrounding its use.

A 2012 meta-analysis brought a more systematic assessment to the earlier trials. Combining the six best randomized controlled studies from the 1960s and 1970s, involving more than five hundred patients, it found a statistically robust and clinically significant beneficial effect of a single LSD dose on alcohol misuse. The effect lasted for as long as six months. The authors concluded that the treatment’s subsequent neglect was puzzling in light of the evidence. In the book’s broader account, LSD therefore occupies two related but distinct histories: it helped expose questions about the chemistry of consciousness, and it became the subject of a once-prominent treatment approach whose evidence was later reconsidered.