A single 25 mg dose of psilocybin, but not 10 mg, reduced depression scores more than a 1 mg control dose over three weeks in adults with treatment-resistant depression. In this phase 2 trial, 233 participants were randomly assigned to 25 mg, 10 mg, or 1 mg of synthetic psilocybin with psychological support. The 25 mg group showed an average 12-point drop on the MADRS depression scale versus a 5.4-point drop in the 1 mg group, a significant difference. The 10 mg group did not differ significantly from control. Response and remission rates at three weeks supported the primary result, but sustained response at 12 weeks was not significantly different.
Three weeks after a single dose, 25 mg of psilocybin, and to a lesser extent 10 mg, improved patient-reported measures of depression severity, anxiety, affect, and functioning in people with treatment-resistant depression. These findings extend the primary results from the largest randomized clinical trial of psilocybin for TRD, highlighting outcomes that matter to patients.