Small phase 2 trial finds psilocybin improves depression symptoms

A Swedish phase 2 trial found that a single psilocybin dose improved depression symptoms, with 53% of recipients in remission after six weeks versus 6% receiving placebo. Karolinska Institutet researchers enrolled 35 adults with moderate to severe recurrent depression in the randomized trial, published in JAMA Network Open. Participants received either 25 milligrams of psilocybin or niacin as an active placebo, alongside five sessions of psychotherapeutic support. Clinician-rated depression scores improved more with psilocybin eight days after treatment, and the advantage persisted at 15 and 42 days. The difference was no longer statistically confirmed after one year. Two psilocybin recipients developed severe, persistent anxiety requiring medical attention. Almost everyone correctly guessed their treatment, complicating separation of drug effects from expectations.