Treatment with LSD and psilocybin at the department of psychiatry at Frederiksberg Hospital in Denmark from 1960 to 1973: an analysis of 324 cases

Patients treated with LSD or psilocybin at a Danish hospital between 1960 and 1973 who later applied for reparatory compensation received higher doses and more treatment sessions than those who did not apply. Treatment responses were similar between the two groups, but flashbacks were reported by 18.2% of applicants compared to 5.2% of non-applicants. The authors suggest that the high incidence of flashbacks should be considered in future clinical studies of psychedelic treatment for mental disorders.

Study at a glance

Abstract

Background Recent studies have suggested that psychedelics such as lysergic acid diethylamide (LSD) and psilocybin might benefit patients with mental illness. This revival calls for revisiting the field’s past experiences with these agents. From 1960 to 1973, many patients were treated with LSD and/or psilocybin at the Department of Psychiatry at Frederiksberg Hospital in Denmark. Here, we analyze the case material/medical records of 324 of these patients. Specifically, we aimed to estimate whether patients who applied for reparatory compensation (applicants; n = 93) as per the Danish LSD Damages Law had worse responses and were more affected by adverse events related to psychedelic treatment than those who did not (non-applicants; n = 231).Materials and Methods Data from the LSD archive at Frederiksberg City Archives were reviewed, and data regarding patient characteristics and LSD/psilocybin treatment (dose, effect, and adverse events) were extracted. Data were compared between applicants and non-applicants using independent samples t-tests, Mann–Whitney U tests, chi-square tests, and Fisher’s exact tests, as appropriate.Results Applicants were treated with higher LSD doses (median LSD dose-index: 31 vs. 21, p = 0.040) and received more treatments (median: 14 vs. 10, p = 0.005) than the non-applicants. Treatment responses did not differ significantly between applicants and non-applicants. Flashbacks were registered for a larger fraction of the applicants compared to non-applicants (18.2% vs. 5.2%, p < 0.001).Conclusions The high incidence of flashbacks should be taken into account in future clinical studies examining psychedelic treatment of patients with mental disorders.