A review of 13 psilocybin-assisted therapy trials involving 606 people found no clear overall antidepressant effect when results were pooled, with the average effect missing statistical significance and study results varying widely. Trial design mattered: control group type explained 98.7% of the differences between studies, and protocols with 2–5 psilocybin sessions showed stronger effects than more intensive approaches. The takeaway is not that psilocybin “doesn’t work,” but that results depend heavily on the therapy structure, comparison group, and study quality.