A new review suggests psychedelic treatments such as psilocybin 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 for which 40–60% of patients gain limited relief from standard therapies. After analysing published studies and preliminary data, researchers found stronger evidence supporting psychedelics than cannabinoids like THC or CBD.
Psilocybin appears to affect the brain’s default mode network, which is linked to rumination and is overactive in OCD. Cannabis, by contrast, mainly targets CB1 receptors associated with anxiety and compulsive behaviour, but does not appear to produce durable symptom improvement.
Early clinical trials, including studies from Yale and Brown universities, show that single or multiple doses of psilocybin can reduce OCD symptoms and help patients gain insight into their need for control. Researchers caution that more rigorous trials are needed, particularly given psilocybin’s legal status and the challenges of conducting blinded psychedelic studies.
