Control Group Outcomes in Trials of Psilocybin, SSRIs, or Esketamine for Depression: A Meta-Analysis

Area of Science:

• Psychiatry
• Neuroscience
• Pharmacology

Background:

• Psilocybin demonstrates rapid and potent antidepressant effects, often exceeding conventional treatments.
• Concerns exist regarding potential bias in psilocybin trials due to functional unblinding and participant expectations.

Purpose of the Study:

• To compare depression treatment outcomes in control groups across randomized clinical trials.
• To evaluate control treatment outcomes from trials involving psilocybin, SSRIs, and esketamine.

Main Methods:

• A meta-analysis of double-blind trials for major depressive disorder (MDD) or treatment-resistant depression (TRD) was conducted.
• Included trials utilized the Montgomery-Åsberg Depression Rating Scale (MADRS) and had relevant control arms.
• Data from 17 trials (4 psilocybin, 2 esketamine, 11 SSRIs) were pooled using random-effects models.

Main Results:

• Participants in psilocybin control groups showed significantly less improvement in MADRS scores compared to control groups in SSRI and esketamine trials.
• MADRS response rates were lower in psilocybin control groups (14-23 percentage points lower than SSRI/esketamine controls).
• Dropout rates were substantially lower for psilocybin and esketamine trials compared to SSRI trials.

Conclusions:

• Control treatment outcomes in psilocybin trials suggest less improvement than in SSRI or esketamine trials.
• The antidepressant efficacy of psilocybin may be overestimated relative to SSRIs and esketamine.
• Further research is needed to address potential biases and confirm psilocybin's true treatment effect.