Early LSD treatment in Denmark from 1960 to 1974: An analysis of possible and long-lasting changes in the adult personality following psychedelic treatment. A historical retrospective cohort study

In view of the renewed interest in psychedelics in psychiatry it is timely to analyze psychedelic treatment in historical cohorts. Recently the therapeutic efficacy of psychedelics has been linked to the so-called phenomenon of “connectedness.” The aim of the present study was to explore whether long-lasting personality changes were observed in any of the 151 Danish psychiatric patients who were treated with Lysergic acid diethylamide (LSD) from 1960 to 1974. The exploration included a reanalysis of a subgroup as well from a 1964 Danish historical cohort. Medical records and other case materials of the above mentioned 151 patients are kept in the Danish State Archives. The present author was granted access to the LSD case materials in the Danish State Archives, and respected confidentiality per the Archives Law. According to the LSD Damages Law from 1986, they all received financial compensation for LSD-inflicted harm. Analysis did not reveal any personality changes such as “connectedness;” however, other lasting personality changes were observed in 2 to 4 patients and in quite a few patients unwanted effects persisted for weeks or months following acute treatment. In the present analysis of the 1964 cohort, the same percentage of patients improved with LSD treatment as in the historical analysis. In the latter, however, little attention was given to side effects, such as suicide attempts, suicides, and one homicide. Future psychedelic research with psychiatric patients should respect the potential toxicity of LSD and other psychedelics and meticulously monitor possible side effects.