Psilocybin-Assisted Therapy for Severe Alcohol Use Disorder: Feasibility, Clinical Efficacy & (Neuro)Cognitive Mechanisms

Psilocybin-Assisted Therapy for Severe Alcohol Use Disorder: Protocol for a Double-Blind, Randomized, Placebo-Controlled, 7-month Parallel-Group Phase II Superiority Trial A substantial proportion of patients with alcohol use disorder does not respond to available treatments, which calls for the development of new alternatives. In parallel, psilocybin-assisted therapy for alcohol use disorder has recently yielded promising preliminary results. Building on extant findings, the proposed study aims to determine the feasibility and preliminary clinical efficacy of psilocybin-assisted therapy as a complementary intervention during inpatient rehabilitation for severe alcohol use disorder, and to characterize associated changes in the two key neurocognitive systems identified by dual-process models of addiction. In this double-blind, randomized, placebo-controlled, 7-month parallel-group phase II superiority trial, 62 participants aged 21-64 years will be enrolled to undergo psilocybin-assisted therapy within the context of a 4-week inpatient rehabilitation for severe alcohol use disorder. The experimental group will receive a high dose of psilocybin (30 mg), whereas the control group will receive an active placebo dose of psilocybin, both within the context of a brief standardized psychotherapeutic intervention. The primary clinical outcome is the between-group difference in terms of the change in percentage of heavy drinking days from baseline to four weeks post-hospital discharge, whilst safety and feasibility metrics will also be reported as primary outcomes. Key secondary assessments include between-group differences in terms of changes in 1) drinking behavior parameters up to six months post-hospital discharge, 2) phosphatidyl-ethanol blood concentration, an objective biomarker of alcohol consumption, 3) symptoms of depression, anxiety, trauma, and global functioning, 4) neuroplasticity and key neurocognitive mechanisms associated with addiction, 5) psychological processes and alcohol-related parameters.