Why was early therapeutic research on psychedelic drugs abandoned?

Background Advocates of the therapeutic use of psychedelic drugs have argued that a promising approach to treatment was prematurely abandoned in the 1960s primarily because of Richard Nixon's ‘War on Drugs’. This paper (1) briefly describes research in the 1950s and 1960s in North America on the use of LSD to treat alcohol dependence, anxiety in terminal illness, and anxiety and depression; and (2) discusses the factors that led to its abandonment. Method An analysis of historical scholarship on psychedelic research in the 1950s, 1960s and 1970s in North America. Results Research on psychedelic drugs in psychiatry was abandoned for a number of reasons that acted in concert. A major factor was that clinical research on psychedelic drugs was caught up in the tighter regulation of pharmaceutical research after the Thalidomide disaster in 1963. Psychedelic drugs also presented special challenges for randomised, placebo-controlled clinical trials in the 1970s that were not as positive as the claims made by their advocates in the 1950s and 1960s. Clinical research became more difficult after 1965 when Sandoz ceased providing psychedelic drugs for research and their nonmedical use was prohibited in 1970. Conclusions The demise of psychedelic drug research was not solely due to the ‘War on Drugs’. It was hastened by tighter regulation of pharmaceutical research, the failure of controlled clinical trials to live up to the claims of psychedelic advocates, and the pharmaceutical industry's lack of interest in funding clinical trials.