Originally appearing at http://www.economist.com/node/18864332?story_id=18864332. THE psychedelic era of the 1960s is remembered for its music, its art and, of course, its drugs. Its science is somewhat further down the list. But before the rise of the counterculture, researchers had been studying LSD as a treatment for everything from alcoholism to obsessive-compulsive disorder (OCD), with promising results. Timothy Leary, a psychologist at Harvard University, was one of the best-known workers in the field, but it was also he who was widely blamed for discrediting it, by his unconventional research methods and his lax handling of drugs. Now, the details of Leary’s research will be made public, with the recent purchase of his papers by the New York Public Library. These papers will be interesting not only culturally, but also scientifically, as they reflect what happened between the early medical promise of hallucinogens and their subsequent blacklisting by authorities around the world. American researchers began experimenting with LSD in 1949, at first using it to simulate mental illness. Once its psychedelic effects were realised, they then tried it in psychotherapy and as a treatment for alcoholism, for which it became known at the time as a miracle cure. By 1965 over 1,000 papers had been published describing positive results for LSD therapy. It, and its close chemical relative psilocybin, isolated from hallucinogenic mushrooms, were reported as having potential for treating anxiety disorders, OCD, depression, bereavement and even sexual dysfunction. Unfortunately, most of the studies that came to these conclusions were flawed: many results were anecdotal, and control groups were not established to take account of the placebo effect. Still, the field was ripe for further study. But alongside growing public fear of LSD, Leary’s leadership had become a liability. He was seen less and less as a disinterested researcher, and more and more as a propagandist. In 1962, amid wide publicity, the Harvard Psilocybin Project was shut down. Leary took his research to an estate in upstate New York, where he also hosted a stream of drug parties. Eventually both LSD and psilocybin were proscribed. Which was a pity because, like many other drugs the authorities have taken against as a result of their recreational uses, hallucinogens have medical applications as well. But time heals all wounds and now, cautiously, study of the medical use of hallucinogens is returning. Psilocybin has shown promise in treating forms of OCD that are resistant to other therapies, in relieving cluster headaches (a common form of chronic headache) and in alleviating the anxiety experienced by terminally ill cancer patients. The first clinical study of LSD in over 35 years, also on terminally ill patients, is expected to finish this summer. Peter Gasser, the Swiss doctor leading the experiment, says that a combination of LSD and psychotherapy reduced anxiety levels of all 12 participants in the study, though the statistical significance of the data has yet to be analysed. Research into LSD is not confined to medicine. Franz Vollenweider, of the Heffter Research Institute in Zurich, for example, is scanning people’s brains to try to understand how hallucinogenic drugs cause changes in consciousness. And biotechnology may lead to a new generation of hallucinogenic drugs. Edwin Wintermute and his colleagues at Harvard have engineered yeast cells to carry out two of six steps in the pathway needed to make lysergic acid, the precursor of LSD. They hope to add the other four shortly. Once the pathway has been created, it can be tweaked. That might result in LSD-like drugs that are better than the original. Even if that does not happen, making lysergic acid in yeast is still a good idea. The chemical is used as the starting point for other drugs, including nicergoline, a treatment for senile dementia. The current process for manufacturing it is a rather messy one involving ergot, a parasite of rye. It may, of course, be that LSD has no clinical uses. Even when no stigma attaches to the drugs involved, most clinical trials end in failure. But it is worth seeing whether LSD might fulfill its early promise. And if the publication of Leary’s archive speeds that process up by exorcising a ghost that still haunts LSD research, then the New York Public Library will have done the world a service. The near-completion of MAPS’ Swiss study of LSD-assisted psychotherapy for end-of-life anxiety is a chance to take note of the resurgence of psychedelic research after decades of taboo. This article describes the long history of psychedelic psychotherapy, the explosion of recreational use leading to the shutting down of psychedelic research, and the recent return of these substances to mainstream science and medicine. The recent publication of Timothy Leary’s archives indicates the world is ready to move beyond its old fear of psychedelics and to once again take an honest, rational look at their risks and benefits for psychological, emotional, and spiritual health.