Scientific American is running a broad overview of past and present research with hallucinogens:
Before 1972, close to 700 studies with psychedelic drugs took place. The research suggested that psychedelics offered significant benefits: they helped recovering alcoholics abstain, soothed the anxieties of terminal cancer patients, and eased the symptoms of many difficult-to-treat psychiatric illnesses, such as obsessive-compulsive disorder.
For example, between 1967 and 1972 studies in terminal cancer patients by psychiatrist Stanislav Grof and his colleagues at Spring Grove State Hospital in Baltimore showed that LSD combined with psychotherapy could alleviate symptoms of depression, tension, anxiety, sleep disturbances, psychological withdrawal and even severe physical pain. Other investigators during this era found that LSD may have some interesting potential as a means to facilitate creative problem solving.
Between 1972 and 1990 there were no human studies with psychedelic drugs. Their disappearance was the result of a political backlash that followed the promotion of these drugs by the 1960s counterculture. This reaction not only made these substances illegal for personal use but also made it extremely difficult for researchers to get government approval to study them.
Things began to change in 1990, when ‘open-minded regulators at the FDA decided to put science before politics when it came to psychedelic and medical marijuana research,’ says Rick Doblin, a public policy expert and head of the Multidisciplinary Association for Psychedelic Studies (MAPS). ‘FDA openness to research is really the key factor. Also, senior researchers who were influenced by psychedelics in the sixties now are speaking up before they retire and have earned credibility.’ Chemist and neuropharmacologist David E. Nichols of Purdue University adds, ‘Baby boomers who experienced the psychedelic sixties are now mature scientists and clinicians who have retained their curiosity but only recently had the opportunity to reexplore these substances.’