Effect of psilocybin therapy on suicidal ideation, attempts, and deaths in people with psychiatric diagnoses: a systematic review and meta-analysis.

BackgroundSuicidal ideation, attempts, and deaths present a major and tragic public health concern. Recent trials of psilocybin therapy (PT) have shown promise in treating treatment-resistant depression and have found a reduction in suicidal ideation. Given the growth of PT research, there is a need to further understand its effect on suicidal ideation, attempts, and deaths.ObjectiveTo assess and synthesize evidence on the effects of PT on suicidal ideation, attempts, and deaths in psychiatric patients.DesignPRISMA-compliant systematic review and meta-analysis.Data sourceMEDLINE, EMBASE, Cochrane, and PsychINFO.MethodDatabases were searched for randomized controlled trials of PT in adults with psychiatric diagnoses that reported suicide outcomes (ideation, attempts, and deaths). Abstract and full-text screening were conducted, and suicide outcomes were extracted. Meta-analysis was performed with a random effects model to assess changes in suicide outcomes compared to control through the standardized mean difference (SMD). Assessment of heterogeneity, risk of bias, and subgroup analysis was completed.ResultsNine studies were included (N = 593; 335 psilocybin & 258 control). Two studies were excluded from meta-analysis because suicide-related outcomes data were not available. Participants with PT experienced a small and significant decrease in suicidal ideation compared to control (k = 7, SMD = -0.24, 95% CI -0.42 to -0.06, p = 0.008, I2 = 0%). There was no publication bias found. Subgroup analysis found no significant differences between groups. No study reported suicide attempts or suicide deaths. Two studies had a high risk of bias.ConclusionPsilocybin therapy may reduce suicidal ideation in adults with psychiatric diagnoses. Current studies are limited by small sample size, lack of follow-up data, and assessment of blinding.Trial registrationCRD42023445706.