Single-Dose Psilocybin Rapidly Improves MDD Symptoms, RCT Finds
Key Clinical Summary
- A randomized clinical trial found that a single 25-mg dose of psilocybin significantly reduced depressive symptoms in adults with recurrent major depressive disorder (MDD) compared with active placebo.
- Improvements were observed within 8 days and remained significant through 6 weeks on clinician-rated assessments.
- Psilocybin was generally well tolerated, although some participants experienced transient anxiety and other adverse effects during treatment.
A single dose of psilocybin was associated with a significant reduction in depressive symptoms within 2 days of administration in patients with major depressive disorder (MDD), according to randomized control trial results published in JAMA Network Open. The effects of the therapy remained for over 3 months.
Study Findings
The double-blind, placebo-controlled trial conducted in Sweden enrolled 35 adults aged 20 to 64 years with recurrent MDD with moderate to severe depressive symptoms. Participants were randomly assigned to receive either a single 25 mg dose of psilocybin or 100 mg of niacin as an active placebo, along with 5 psychotherapy appointments over 17 days. All participants completed structured psychological support sessions before, during, and after dosing.
The primary outcome was between-group differences in self-rated Montgomery-Åsberg Depression Rating Scale (MADRS) score at day 8. Researchers reported a significantly greater reduction in MADRS scores in the psilocybin group compared with the niacin group (-7.27; 95% CI, -12.89 to -1.65; P = .01). Significant symptom reductions in the psilocybin group were also observed at days 15 (mean difference, −11.03; 95% CI, −16.65 to −5.42; P < .001) and 42 (mean difference, −8.33; −13.94 to −2.71; P = .004).
At the 6-week assessment, remission occurred in 52.9% of participants who received psilocybin compared with 5.6% of participants who received niacin. Self-reports indicated that the effects from psilocybin endured up to day 102. The differences had resolved by day 365 (mean difference, −3.68; −9.30 to 1.94; P = .20).
Investigators reported that adverse events were common but typically mild to moderate and transient. In the psilocybin group, anxiety, headache, nausea, and transient increases in blood pressure were among the reported effect. Two participants experienced prolonged severe anxiety requiring additional support, although no treatment-related serious adverse events were reported.
The authors also noted that most participants correctly identified whether they had received psilocybin or placebo, highlighting ongoing challenges with maintaining blinding in psychedelic research: “We conclude that using niacin as an active placebo did not achieve the blinding integrity generally expected from a double-blind RCT, even in a psychedelic-naive population.”
Clinical Implications
The findings suggest that psilocybin-assisted therapy may provide a rapid-acting treatment approach for adults with recurrent major depressive disorder. Unlike conventional antidepressant therapies that often require several weeks before improvement is observed, participants receiving psilocybin demonstrated measurable symptom reductions within days.
The study adds evidence supporting investigation of psychedelic-assisted therapies in depressive disorders beyond treatment-resistant populations. Researchers emphasized that psilocybin administration occurred within a controlled clinical environment that included structured psychological support, monitoring, and follow-up care.
Clinicians should also consider the safety findings when interpreting the results. Although most adverse events were temporary and manageable, acute anxiety reactions occurred in some participants. The authors noted that larger studies are needed to further evaluate safety, durability of response, and optimal treatment protocols.
The relatively small sample size and difficulties with treatment masking may limit interpretation of efficacy findings. Investigators stated that additional randomized trials with larger populations will be important to confirm clinical benefit and establish broader applicability.
Expert Commentary
“Our findings indicate that psilocybin might be a valuable addition to current treatments because of its rapid onset and relatively long-lasting effects, although the duration may not be as long as suggested by previous uncontrolled studies,” wrote Hampus Yngewe, MD, MSc, Center for Psychiatry Research, Karolinska Institutet, and study co-authors. “Repeated dosing or maintenance therapy might therefore be needed to prevent relapse.”
Reference
