This first systematic review of psychedelic-assisted treatments for alcohol, tobacco, and other substance use disorders examined 37 studies involving 2,035 participants. The best evidence of efficacy came from a phase 2 randomized controlled trial of psilocybin for alcohol use disorder and a phase 2 trial of ketamine for alcohol use disorder. Psilocybin-assisted treatment for alcohol use disorder appears to have the strongest evidence among all major psychedelic-assisted treatments. No serious adverse events were reported across any study. The review recommends that future research report all safety events, identify contraindications, mitigate participant blinding, use factorial designs, and develop a core outcome set.
Military veterans who attended psilocybin or ayahuasca retreats showed significant improvements in eight measures of mental health and community reintegration, with the largest gains in depression (29.1% reduction on the PHQ-9) and PTSD (26.1% reduction on the PCL-5). Psilocybin retreats produced greater improvements on seven of eight outcomes, while ayahuasca retreats yielded slightly larger PTSD reductions (26.4% vs. 24.8%). Male participants improved more on all outcomes except PTSD, where females showed a larger reduction (32.1% vs. 24.1%). Veterans with worse initial symptoms benefited most. The findings suggest psychedelic retreats could offer a holistic treatment framework addressing psychological well-being, community factors, and civilian reintegration.