5-HT2A Agonist Psilocybin in the Treatment of Tobacco Use Disorder

This is a multi-site, double-blind, randomized clinical trial of the 5-HT2A receptor agonist psilocybin for smoking cessation. The investigators previously conducted an open-label pilot trial (N = 15) of psilocybin paired with cognitive behavior therapy (CBT). Data showed a biologically-verified 7-day point-prevalence abstinence rate of 67% at 12 months and 60% at 2.5 years (continuous abstinence rates: 53% and 47%, respectively). The investigators are now conducting an open-label randomized comparative efficacy trial of psilocybin vs. nicotine patch, both in combination with CBT. Interim results (N = 44; 22 per group) show greater biologically-verified abstinence rates at 12 months for psilocybin: 7-day point-prevalence: 59% vs. 27%; continuous abstinence: 36% vs. 9%. Despite these promising findings, the investigators have yet to conduct a double-blind study of psilocybin for smoking cessation. Furthermore, previous psilocybin study samples have been largely White with higher socioeconomic status (SES). The current trial will address these issues across four sites with experience in conducting psilocybin research: Johns Hopkins, the University of Alabama at Birmingham (UAB), and New York University (NYU). A diverse sample with regard to ethno-racial identity and SES will be recruited at each site. The proposed double-blind study will treat 66 participants (22 at each site), randomized to receive either: 1) psilocybin; 30 mg in session 1 and either 30 or 40 mg in session 2, with sessions 1 week apart; or 2) niacin; 150 mg in session 1 and either 150 mg or 200 mg in session 2, with sessions 1 week apart. Niacin was selected because it has been used as an active placebo in two previous randomized therapeutic trials of psilocybin, and the FDA has informed the investigators that niacin is the FDA's preferred active placebo for psilocybin. CBT will be administered to both groups and will allow the investigators to test psilocybin's efficacy above and beyond an established treatment approach. Biochemically-confirmed 7-day point-prevalence abstinence will be assessed throughout for up to 12 months. The investigators hypothesize that psilocybin (compared to niacin) will cause increased biologically-confirmed 7-day point-prevalence abstinence at 12-month follow-up. Based on pilot data, the investigators will test cognitive/psychological mediators of treatment response. The investigators hypothesize that psilocybin will be associated with improved cognitive control and decreased anticipation of withdrawal relief (from smoking) 1 day after the target quit date, which will be associated with greater 7-day point-prevalence abstinence at 12- month follow-up. This trial will provide a rigorous test of efficacy in a diverse study sample, and test relevant mechanisms, for an innovative smoking cessation treatment showing potential for substantial efficacy.