Dose-dependent link between cannabis use, psychosis relapse

(HealthDay)—Cannabis use may raise the risk of psychosis relapse, according to a study published online Sept. 28 in JAMA Psychiatry.

Researchers looked at 220 patients—90 women and 130 men, aged 18 to 65—who were diagnosed for the first time with psychosis.

The researchers found that the risk that patients would relapse was 13 percent higher when they used cannabis than when they didn't. The odds appeared to go up when the patients used more cannabis. This suggests that cannabis use raises the risk of relapse, instead of the other way around, the researchers said.

"We show that pot use causes an increase in the risk of relapse in psychosis and demonstrate that alternative explanations are unlikely to be true," study author Sagnik Bhattacharyya, M.D., Ph.D., of King's College London, told HealthDay. "It would be appropriate to at least aim for reduction in pot use in patients with psychosis if complete abstinence is not realistic."