An 8-week Phase 2 Clinical Trial to Evaluate the Safety, Tolerability and Efficacy of Psilocybin-assisted-psychotherapy in Adults With Cannabis Use Disorder: A Proof-of-Concept Study

Cannabis is the most commonly used psychoactive substance in Canada (Lowry \& Corsi, 2020). A sub-group of cannabis users develop a condition known as Cannabis Use Disorder (CUD), which is defined as a regular pattern of cannabis use that causes performance difficulty at work, school and relationships (Hasin et al., 2013). A review of current treatments available for CUD indicate the lack of a pharmacological and psychological treatment with high success rates, which highlights the importance of exploring potential psychosocial interventions for the treatment of CUD. Given the evidence of psilocybin's therapeutic potential in the treatment of substance use disorders (de Veen et al., 2017), we aim to conduct a study using psilocybin-assisted-psychotherapy in the treatment of CUD. The study aims to evaluate the feasibility, safety, tolerability and potential therapeutic effect of 2 doses \[25 mg\] of psilocybin administered as part of an 8-week Motivational Enhancement Therapy (MET) and supportive therapy. This trial will be the first to evaluate the potential treatment effects of psilocybin on symptoms of CUD.