High-potency cannabis, or frequent use, raises the risk of psychosis

ROYAL GORILLA, Girl Scout Cookies and Fat Banana are just a few of the improbably named strains of high-potency cannabis out there. In the former, levels of tetrahydrocannabinol (THC), the chemical behind the psychological effects of cannabis, are above 25%. Reviewers describe it as “overwhelming” for novices and a “beautiful euphoric couch-locking experience” for others.

However enticing that may sound, regular use of cannabis with a potency greater than 10% increases the risk of developing psychosis five-fold, according to a study published this week by the Lancet. It also found that using less potent strains daily increased the risk three-fold. Marta Di Forti, a clinical scientist at Kings College in London, and her colleagues looked at cannabis use among 901 European patients newly diagnosed with psychosis. A non-smoking control group was recruited from the general population.