Research library / Clinical trial
Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial
Davis AK, Barrett FS, May DG, et al. JAMA Psychiatry 2021;78(5):481-489
In this Johns Hopkins trial, 27 adults with major depression who were not taking antidepressants were randomly assigned to start psilocybin therapy right away or after an eight-week wait. Treatment was two psilocybin sessions with about 11 hours of supportive therapy. Twenty-four people completed it. Depression scores dropped steeply in the treated group compared with those still waiting, and about seven in ten responded to treatment, with roughly half in remission four weeks later. The effect sizes were very large. The comparison group simply waited rather than receiving a placebo, so the study cannot separate the drug from the expectation of getting a novel treatment, and the sample was small with short follow-up. A later paper reported five-year outcomes from the same group.
What it found
- GRID-HAMD scores at weeks 1 and 4 after treatment were about 8 in the immediate group vs about 23.5 in the waiting group at matching timepoints (Cohen d about 2.5)
- 71% had a clinically significant response at weeks 1 and 4
- 58% at week 1 and 54% at week 4 were in remission