The impact of antidepressant discontinuation prior to treatment with psilocybin for treatment-resistant depression.

In a phase II randomized controlled trial of 233 participants with treatment-resistant depression, those who discontinued antidepressant drugs before receiving psilocybin showed no worsening of depression severity during the discontinuation period, comparable baseline suicidality, and no compromise in psilocybin's treatment efficacy or subjective psychedelic effects relative to those who entered the trial antidepressant-free. The findings suggest that antidepressant discontinuation does not limit the feasibility of psilocybin treatment for treatment-resistant depression and support the homogeneity of psilocybin's effects as a monotherapy.

Study at a glance

Abstract

It has been suggested that the recent use and discontinuation of antidepressant drugs compromises the action of psilocybin. As evidence is only available from small or uncontrolled samples, this post hoc analysis investigated this using data from the largest, phase II, randomized controlled trial of psilocybin treatment to date. Data from 233 participants with treatment-resistant depression (TRD) who received 25 mg, 10 mg, or 1 mg of investigational drug COMP360 psilocybin (a proprietary, pharmaceutical-grade synthetic psilocybin formulation, developed by the sponsor, Compass Pathfinder Ltd.), administered with psychological support, were compared for groups of participants who either discontinued one or more antidepressant drugs during screening or entered the trial antidepressant drug free. Measures of depression symptom severity change during the antidepressant drug discontinuation period, baseline suicidality, acute subjective psychedelic effects, and the study's primary endpoint (change in depression symptom severity between Baseline and Week 3) are described for both groups. Antidepressant drug discontinuation was not related to worsening of depression severity before Baseline. Suicidality was comparable between groups at Baseline. Psilocybin treatment efficacy and the subjective psychedelic experience did not appear to be compromised by antidepressant drug discontinuation. Thus, it does not limit the feasibility of psilocybin treatment for the future. These findings also support the overall homogeneity of our findings with psilocybin treatment as a monotherapy for TRD. The prior contradictory reports may come to appear misleading.