Real-World Psilocybin Therapy for Treatment-Resistant Depression: A Retrospective Observational Study

Area of Science:

• Psychiatry
• Neuroscience
• Pharmacology

Background:

• Psilocybin shows promise for depression in clinical trials.
• Real-world effectiveness and safety for treatment-resistant depression (TRD) are largely unknown.
• Switzerland permits limited medical use of psilocybin for TRD.

Purpose of the Study:

• To examine real-world antidepressant outcomes, safety, and feasibility of psilocybin therapy for TRD.
• To assess repeated dosing sessions in a therapeutic setting.

Main Methods:

• Retrospective analysis of 19 TRD patients treated with psilocybin (20-35 mg) at Psychiatric University Hospital Zurich.
• Assessment of depression severity using Montgomery-Åsberg Depression Rating Scale (MADRS) and Beck Depression Inventory II (BDI).
• Analysis of changes from baseline to post-treatment, including response and remission rates.

Main Results:

• Significant reduction in MADRS scores (M=30.78 to M=19.89, Hedges' g = 1.37) and BDI scores (M=32.33 to M=23.28, Hedges' g = .77).
• Response rates: 33.3% (MADRS) and 27.8% (BDI). Remission rates: 22.2% (MADRS) and 27.8% (BDI).
• No serious adverse events were documented.

Conclusions:

• Psilocybin therapy is associated with clinically meaningful reductions in depressive symptoms for TRD patients in a real-world setting.
• Response and remission rates were lower than previously reported in controlled trials.
• Findings suggest feasibility of psilocybin for TRD care, acknowledging study limitations (small sample size, retrospective design).