Review pools psilocybin trials and reports large drops in depression and anxiety scores

The question

Does psilocybin therapy reduce symptoms in people with depression, anxiety and other mood problems, based on the published research to date?

What they did

The authors carried out a systematic review and meta-analysis, meaning they searched the published literature and statistically combined the results of separate studies. They said they followed PRISMA 2020, a standard checklist for reporting reviews. They grouped outcomes into anxiety/major depressive disorder and into mood disorders more broadly. The abstract does not report how many studies or participants were included.

What they found

For anxiety and major depressive disorder, the pooled effect was a standardized mean difference of -1.438 (95% confidence interval -1.729 to -1.146, p < 0.001). For mood disorders, it was -1.476 (95% confidence interval -1.773 to -1.178, p < 0.001). A standardized mean difference of this size means symptom scores fell substantially compared with the comparison condition. The authors report that improvements often lasted after a single session, and that a publication-bias check (fail-safe N greater than 5500) suggested the findings were not explained by unpublished negative studies alone.

The fine print

The abstract does not say how many trials or participants were pooled, which studies were included, what the comparison groups were, or how long people were followed. It also does not report how much the results varied between studies, which matters when pooled effects are this large. Psilocybin trials are hard to blind, because participants usually know whether they received an active dose, and that can inflate results. This summary is based on the abstract alone, and the abstract’s language is notably promotional.

What it means

Pooled results from psilocybin studies point to sizeable short-term reductions in depression and anxiety symptoms, but the abstract withholds the basic details needed to judge how solid that estimate is.

Evidence grade: Low. The abstract does not state how many studies or people were pooled, or whether the included studies were randomized and placebo-controlled, so the strength of the underlying evidence cannot be judged.

This summary is based on the study’s published abstract.