The association between diverse psychological protocols and the efficacy of psilocybin-assisted therapy for clinical depressive symptoms: a Bayesian meta-analysis

A Bayesian meta-analysis of 10 clinical trials involving 515 adults with diagnosed depression found that psilocybin-assisted therapy produced a pooled mean reduction of 10.08 points on the 17-Item Hamilton Depression Rating Scale. The psychological protocols used alongside psilocybin varied: manualized directive psychotherapy, manualized nondirective psychological support, non-manualized nondirective psychological support, and non-manualized supportive psychotherapy. Compared with manualized nondirective psychological support, the other three approaches did not differ significantly in their effect on depressive symptoms. The improvement in depressive symptoms was not associated with the type of psychological protocol employed.

Study at a glance

Abstract

Objective Psilocybin-assisted therapy has shown promising efficacy on clinical depressive symptoms. However, diverse psychological support or psychotherapy was performed with psilocybin treatment. This study aimed to explore the association of psychological protocols with the efficacy of psilocybin-assisted therapy for depressive symptoms. Method Five major databases were systemic searched for clinical trials addressing psilocybin-assisted therapy for patients with clinical depressive symptoms. A Bayesian random-effects meta-analysis and meta-regression were performed. The effect size was mean difference (with 95% credible interval) measured by 17-Item Hamilton Depression Rating Scale. Results There were 10 eligible studies including 515 adult patients with clinically diagnosed depression. The psychological protocols could be categorized into four types: (i) manualized directive psychotherapy(k=1); (ii) manualized nondirective psychological support(k=3), (iii) non-manualized nondirective psychological support(k=5); and (iv) non-manualized supportive psychotherapy(k=1). The pooled standard mean difference of psilocybin-assisted therapy was 10.08 (5.03-14.70). Conclusion Compared with manualized nondirective psychological support, the other three psychological approaches did not differ significantly. The improvement of depressive symptoms was not associated with the psychological protocols in adult patients receiving psilocybin-assisted therapy. Systemic review registration Open Science Framework: identifier (osf.io/3YUDV).