Psychiatry professor theorizes that the difference is related to how the substances interact with areas of the brain

A recent review of alternative treatments for obsessive compulsive disorder (OCD) indicates that psychedelic treatments show promise for the disorder while cannabis does not.

Dr Michael Van Ameringen, a psychiatry professor at McMaster University in Ontario, Canada and lead author of the review published in the Journal of Psychiatric Research, said that 40-60 % of OCD patients get either partial or no relief with available treatments, including SSRIs and exposure and response prevention therapy.