A new review suggests psychedelic treatments may help people with obsessive compulsive disorder (OCD), while cannabis shows little evidence of lasting benefit.
The review, led by Dr Michael Van Ameringen of McMaster University and published in the Journal of Psychiatric Research, examined alternative treatments for OCD, a condition where 40–60% of patients see limited improvement with standard therapies. After analysing published studies, conference data and preliminary findings, researchers found stronger evidence supporting psychedelics such as psilocybin than cannabinoids like THC or CBD.
Van Ameringen said the difference may lie in how the substances affect the brain. Psilocybin appears to reduce activity in the brain’s default mode network, which is linked to rumination and is overactive in OCD. Cannabis, while influencing anxiety-related pathways, has not shown sustained symptom relief.
Early clinical trials, including a Yale-led study using a single dose of psilocybin, reported improvements in OCD symptoms compared with placebo. Researchers stress that further controlled studies are needed and warn that despite encouraging signs, psychedelics are not a cure and face legal and research barriers.
