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Does Psilocybin Require Psychedelic Effects to Treat Depression? A 4-Week, Double-Blind, Proof-of-Concept Randomized Controlled Trial (PSI-RIS)
Psilocybin, the chemical component of "magic mushrooms", has been administered with psychotherapy in several randomized clinical trials (RCTs) showing large and sustained antidepressant effects. In healthy volunteers, the psychedelic effects of psilocybin have been shown to be blocked by administration of serotonin (5HT)2A receptor antagonists such as risperidone. The purpose of this "double dummy" proof-of-concept trial is to evaluate whether psilocybin's antidepressant effects are dependent on its psychedelic effects. Sixty participants with treatment-resistant depression will be randomly assigned to one of three groups: 1) Psilocybin 25 mg plus risperidone 1 mg; 2) Psilocybin 25 mg plus placebo; and 3) Placebo plus risperidone 1 mg. The investigator's hypothesize that the combination of psilocybin and risperidone will be well tolerated, safe, and will block the psychedelic effects of psilocybin in patients diagnosed with treatment-resistant depression.
Details
| Lead sponsor | Centre for Addiction and Mental Health |
|---|---|
| Phase | Phase 2 |
| Status | COMPLETED |
| Enrolment | 41 |
| Start date | 2023-07-01 |
| Completion | 2026-04-14 |
Conditions
- Treatment-resistant Depression
Interventions
- Psilocybin 25 mg
- Risperidone 1 MG
- Placebo
Primary outcomes
- Feasibility of administering psilocybin (25mg) with risperidone (1mg) — 4 weeks
Percentage of participants recruited, randomized, and retained. - Tolerability and safety of administering psilocybin (25mg) with risperidone (1mg) — 4 weeks
Frequency of dropouts attributed to adverse effects or serious adverse events
Countries
Canada