Efficacy and Safety of Psilocybin in Treatment-Resistant Major Depression

The study aims to investigate the safety and efficacy of oral psilocybin administered under supportive conditions in treatment-resistant major depression (TRD). The study is a bi-centric, prospective, randomized, active placebo-controlled study investigating the effects of 25 mg and 5 mg (p.o.) psilocybin versus placebo (100 mg nicotinamide) in a psychotherapeutic context in 144 patients with TRD from moderate to severe degree (ICD-10 F32/F33). After giving written informed consent and down-titration of their monoaminergic medication under supervision of the treating psychiatrist and the study team, patients will be randomly assigned to one of four trial arms using an online randomization tool: 1) receiving placebo (100 mg nicotinamide) at the first session and the full dose (25 mg) at the second; 2) receiving the presumably sub-effective dose (5 mg) at the first session and the full dose (25 mg) at the second; 3a) receiving the full dose (25 mg) at the first session and 5 mg at the second; 3b) receiving the full dose at both sessions. The two dosing sessions are accompanied by three preparatory and four integration sessions. Drug administration must occur under psychotherapeutic conditions. Two trained therapists (one male, one female) will be assigned to each patient and be present during each dosing, preparatory and integration sessions. We will follow the safety guidelines provided by Johnson et al. (2), including a thorough preparation, establishment of trust/rapport, a safe and pleasing physical environment and sufficient interpersonal support. For safety reasons and close monitoring, patients will stay hospitalized for one night after each dosing session (i.e. in-patient setting).