Psilocybin Treatment of Major Depressive Disorder With Co-occurring Alcohol Use Disorder

The objectives of this double-blind, placebo-controlled study are to test the hypotheses that a single high (25 mg) oral dose of psilocybin will lead to enduring reductions in depressive symptoms (as measured by the clinician-rated grid version of the Hamilton Depression Rating Scale, or GRID-HAMD) and amount of drinking (as measured using the Time Line Follow Back, or TLFB, procedure) compared to placebo in patients with co-occurring MDD and AUD. 90 male and female volunteers who are between the ages of 21 and 65 years old and who meet Diagnostic and Statistical Manual, Fifth Edition (DSM-5) criteria for MDD and AUD will be recruited from the community and complete all study procedures. Volunteers will be randomized to one of two study arms (psilocybin \[N=45\] or placebo \[N=45\]), and will complete a drug administration session paired with a brief Motivational Interviewing intervention for alcohol use. Volunteers will undergo assessments of depression and alcohol use before and after treatment. After primary endpoints are measured, all volunteers will receive a second, unblinded intervention with a single high dose of psilocybin (25 mg) to test a secondary hypothesis that two doses of psilocybin are more effective in treating MDD with co-occurring AUD than a single dose.