The efficacy and safety of psilocybin-assisted therapy for major depressive disorder: a meta-analytic review of clinical outcomes
Mohsen Khosravi, Domenico de Berardis, Massimo Tusconi
Mental Wellness April 21, 2026 DOI: 10.4081/mw.2026.40 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Systematic review and meta-analysis Peer reviewed |
|---|---|
| Sample size | 606 |
| Population | Adults with major depressive disorder or treatment-resistant depression |
| Intervention | Psilocybin-assisted psychotherapy |
| Topics | Depression Psilocybin |
| Keywords | Meta-analysis Antidepressant Clinical trial Depression economics Confidence interval Randomized controlled trial Clinical psychology Medline Mean difference Depressive symptoms Significant difference |
| Key findings | Psilocybin-assisted psychotherapy showed no statistically significant overall antidepressant effect, with efficacy highly dependent on trial design, comparator type, and session structure. |
Abstract
This systematic review and meta-analysis synthesized data from 13 clinical trials (n=606) evaluating psilocybin-assisted psychotherapy for major depressive disorder and treatment-resistant depression. Despite early enthusiasm, the pooled standardized mean difference (-0.79, 95% confidence interval: -3.98 to 2.40, p=0.63) revealed no statistically significant overall antidepressant effect, with extreme heterogeneity (I2=96.9%) across studies. Notably, the type of control group (active comparator vs. placebo/waitlist) accounted for 98.7% of between-study variance, with waitlist and low-dose comparators producing exaggerated effect sizes. Session frequency was a significant moderator: 2 to 5 psilocybin sessions yielded larger effects, while more intensive protocols attenuated benefit. Neither participant age nor follow-up duration significantly influenced outcomes. Evidence of reporting bias and small-study effects was detected (Egger’s test p=0.012). Sensitivity analyses demonstrated that no single study accounted for the non-significant pooled result. Overall, psilocybin’s antidepressant efficacy appears highly context-dependent—shaped by trial design, comparator, and session structure—rather than universally robust. These findings underscore the need for larger, rigorously controlled trials to clarify psilocybin’s therapeutic role in depression.
Comparable studies
Other systematic reviews and meta-analyses on psilocybin for depression, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Therapeutic effects of classic serotonergic psychedelics: A systematic review of modern‐era clinical studies Patients with cancer- or illness-related anxiety and depression, major depressive... | 2020 | Systematic review | n = 188 |
| The experimental effects of psilocybin on symptoms of anxiety and depression: A meta-analysis People with elevated symptoms of anxiety and depression | 2020 | Meta-analysis | n = 117 |
| Psychedelics in the treatment of unipolar mood disorders: a systematic review Patients with broadly defined unipolar mood disorders | 2016 | Systematic review | n = 423 |
| Psychedelic therapy for depressive symptoms: A systematic review and meta-analysis. Participants in studies of psychedelic therapy for depressive symptoms (Major... | 2023 | Systematic review with meta-analysis | n = 14 |
| Serotonergic hallucinogens in the treatment of anxiety and depression in patients suffering from a life-threatening disease: A systematic review. Patients with life-threatening diseases and symptoms of anxiety or depression | 2018 | Systematic review | n = 445 |