High-strength cannabis increases risk of mental health problems

Study says 30% of first-time psychotic disorders in south London linked to strong drugs

Frequent cannabis use and high-strength varieties are likely to increase the chance of mental health problems among users, according to researchers behind the largest study of its kind.

Experts have previously flagged a link between cannabis use and psychosis, particularly among vulnerable people with heavy use of the drug. Now research suggests the potency of the cannabis is also important, with patterns in cannabis use linked to how often new cases of psychotic disorders arise in different cities.