What patterns of cannabis use are the most likely to increase someone’s chances of developing psychosis? That’s the question a team of U.K. researchers set out to answer using data from 901 first-episode psychosis patients across Europe and Brazil. The results of their analysis, published Tuesday in The Lancet, describe a clear correlation between daily, high-potency cannabis consumption and psychotic episodes. Yet lead researchers acknowledged that the correlation does not necessarily mean cannabis is the cause of psychosis.
Study Cannot Definitively Pinpoint Cannabis as Cause of Psychosis
Studies that suggest links between cannabis use and mental illness give firepower to policymakers who view legal marijuana as a threat to public health and safety. But a close look at their actual findings almost always reveals a much more complex and less definitive picture of how cannabis consumption intersects with mental illness—and mental wellness.
So what did King’s College London researchers find? Looking at data collected between 2010 and 2015 at 11 sites across Europe and Brazil, researchers selected 901 patients, aged 18-64, who presented to psychiatric services with a first episode of psychosis. Using some complex statistics, researchers compared the cannabis use patterns of the 901 patients with 1237 control subjects from