After clinical trials showed psilocybin could help treat pain, anxiety, and depression in cancer patients, researchers became interested in whether it might also treat substance use disorders. This review of the literature summarizes available trials on psilocybin for addiction. Only one double-blind, randomized clinical trial has examined psilocybin's effect on heavy drinking in adults with alcohol dependence. Several trials are currently underway, but otherwise the evidence is insufficient to draw any conclusions about psilocybin's efficacy for substance use disorders. More well-powered, blinded, randomized controlled trials are needed.
Cannabis use is associated with an increased risk of psychosis. A retrospective chart review of patients hospitalized for a psychosis episode over five years at the American University of Beirut Medical Center found that cannabis users were more likely to be young single males who also used other substances. Frequent cannabis use was linked to a higher likelihood of paranoia and legal problems, but other psychotic symptoms, length of hospital stay, and duration of the psychotic episode did not significantly differ between frequent cannabis users and non-users. Family stressors and a family history of psychotic disorder were associated with a higher likelihood of personal history of violence.