A new review suggests that psychedelic treatments such as psilocybin may help people with obsessive compulsive disorder (OCD), while cannabis shows little evidence of long-term benefit.
The review, published in the Journal of Psychiatric Research and led by Dr Michael Van Ameringen of McMaster University, examined alternative treatments for OCD, a condition for which 40–60% of patients gain limited relief from standard therapies like SSRIs and exposure therapy.
After analysing published studies, conference data and preliminary findings, the researchers found stronger evidence supporting psychedelics, particularly psilocybin, than cannabinoids such as THC and CBD. Van Ameringen said cannabis appears to reduce anxiety and compulsions temporarily but does not provide sustained improvement in OCD symptoms.
By contrast, psilocybin affects the brain’s default mode network, which is linked to rumination and intrusive thoughts and is overactive in OCD. Reducing activity in this network may help ease symptoms.
Early clinical trials included in the review found that a single dose of psilocybin reduced OCD symptoms compared with placebo. Researchers noted that psychedelic trials often combine medication with guided psychological support, which may also contribute to their effectiveness.
While the findings offer hope, scientists stress that further controlled trials are needed and that reducing global barriers to research, including legal restrictions on psilocybin, remains crucial.
