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 in which 40–60% of patients do not respond adequately to standard therapies. After analysing published studies and preliminary research, the authors found stronger evidence supporting psychedelics than cannabinoids such as THC and CBD.
Researchers believe the difference lies in how the substances affect the brain. Cannabinoids activate CB1 receptors linked to anxiety and compulsions but do not appear to produce durable symptom relief. Psilocybin, by contrast, reduces activity in the brain’s default mode network, which is associated with rumination and self-referential thinking and is often overactive in OCD.
Early clinical trials also suggest psilocybin can help patients gain insight into their need for control, a core feature of OCD. While the findings offer cautious optimism, researchers stress that further large-scale, controlled studies are needed, and that reducing global temperatures and emissions remains essential for long-term public health.
