A Double-Blind Trial of Psilocybin-Assisted Treatment of Alcohol Dependence

Several lines of evidence suggest that classic hallucinogens such as psilocybin can facilitate behaviour change in addictions such as alcohol dependence. The investigation is a multi-site, double-blind, active-controlled trial (n=95, 47 per group) contrasting the acute and persisting effects of psilocybin (25-30mg/70kg) to those of diphenhydramine (placebo) in the context of outpatient alcoholism treatment.

The active placebo is diphenhydramine (which has some effects but still, participants almost always knew if they were in the active or placebo arm of the study).

The results were favourable: “Percentage of heavy drinking days during the 32-week double-blind period was 9.7% for the psilocybin group and 23.6% for the diphenhydramine group, a mean difference of 13.9%; (95% CI, 3.0-24.7; F1,86 = 6.43; P = .01). Mean daily alcohol consumption (number of standard drinks per day) was also lower in the psilocybin group. There were no serious adverse events among participants who received psilocybin.“

A rationale for the trial was published in November 2022 (three months after the results were published).

Topic Addiction Alcohol Use Disorder
Compound Psilocybin Placebo
Country United States of America
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Trial Details



Trial Number

Sponsors & Collaborators

NYU Langone Health
This company doesn't have a full profile yet, it is linked to a clinical trial.

Heffter Research Institute
The Heffter Research Institute has been advancing psychedelics (psilocybin) as medicines since 1993.

University of New Mexico
This company doesn't have a full profile yet, it is linked to a clinical trial.

Papers

Psilocybin-induced changes in neural reactivity to alcohol and emotional cues in patients with alcohol use disorder: an fMRI pilot study
This reanalysis of a Phase II study (n=11) investigated psilocybin-induced changes in neural reactivity to alcohol and emotional cues in patients with alcohol use disorder (AUD). Participants received psilocybin (25mg; n=5) or diphenhydramine (antihistamine; 50mg; n=6). Psilocybin increased activity in the medial and lateral prefrontal cortex and left caudate, while decreasing activity in several other brain regions. These findings suggest enhanced goal-directed action, improved emotional regulation, and diminished craving.

Multidimensional Personality Changes Following Psilocybin-Assisted Therapy in Patients With Alcohol Use Disorder: Results From a Double-Blind, Placebo-Controlled Clinical Trial
This reanalysis of a Phase II study (n=84) investigates the effects of psilocybin-assisted therapy (PAT) on personality traits in alcohol use disorder (AUD). Psilocybin (2x, 25-40mg/70kg; n=44) significantly reduced neuroticism and increased extraversion and openness compared to placebo (diphenhydramine, n=40). Decreased impulsiveness correlated with lower alcohol consumption post-treatment, suggesting PAT may normalize abnormal personality traits in AUD.

Percentage of Heavy Drinking Days Following Psilocybin-Assisted Psychotherapy vs Placebo in the Treatment of Adult Patients With Alcohol Use Disorder
This double-blind, active placebo-controlled study (n=95) finds that psilocybin (2x, 25-40mg/70kg) significantly reduced the number of heavy drinking days (10% versus 24% in the placebo group) in the 32-week follow-up period. The trial is the first to test psilocybin for alcoholism (alcohol use disorder, AUD) in a double-blind study.

Data attribution

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