A close up photo of psilocybin mushrooms. Editor’s note: After this publication, The BMJ placed an expression of concernopens in a new tab or window on the study about a methodological error that likely overestimated the benefits of psilocybin. The researchers are currently reviewing and responding to the concern.
A meta-analysis of psilocybin trials confirmed its possible benefit as a depression treatment, but raised questions about its safety and use in clinical practice.
Seven of nine studies included in the analysis showed a significant benefit with psilocybin for adults with depression, favoring it over a comparator treatment (Hedges’ g 1.64, 95% CI 0.55-2.73, P <0.001), reported Athina-Marina Metaxa, MSc, of the University of Oxford in England, and Mike Clarke, DPhil, of ICS-A Royal Hospitals in Belfast, Ireland.
However, prediction intervals were wide and "crossed the line of no difference (95% CI -1.72 to 5.03), indicating that there could be settings or populations in which psilocybin intervention would be less efficacious," the researchers wrote in The BMJ opens in a new tab or window .
Overall, psilocybin treatment was linked with a higher chance for treatment response compared with placebo (risk ratio [RR] 2.02, 95% CI 1.33-3.07), though there was low heterogeneity between the studies for this outcome, they noted. Psilocybin was also linked with a greater chance of depression remission compared with placebo (RR 2.71, 95% CI 1.75-4.20).
Subgroup analyses showed greater efficacy of psilocybin among people with secondary depression, people with previous use of psychedelics, people who were older, and in studies that used self-reported measures of depression symptoms.
"Efficacy did not appear to be homogeneous across patient types — for example, those with depression and a life-threatening illness appeared to benefit more from treatment," Metaxa and Clarke observed.
"Although this review’s findings are encouraging for psilocybin’s potential as an effective antidepressant, a few areas about its applicability in clinical practice remain unexplored," they wrote. It’s "unclear whether the protocols for psilocybin interventions in clinical trials can be reliably and safely implemented in clinical practice," they noted.
In clinical trials, psilocybin therapy is delivered in a non-traditional medical setting, like the one described in this […]
Psilocybin Appears Effective for Depression, but Concerns Linger