Marijuana may bring on temporary paranoia and other psychosis-related effects in individuals at high risk of developing a mental disorder, a preliminary study by researchers at Columbia University Medical Center (CUMC), has said.
The study, published in an online edition of Psychiatry Research, said individuals who had had mild or transient psychotic symptoms such as unusual thoughts and perceptual disturbances without using marijuana or alcohol were considered to be at high risk for psychotic disorder.
Previous studies have found an association between marijuana use and psychosis in the general population, but none have rigorously examined its effects in those at greatest risk for psychosis.
Professor Margaret Haney, in charge of Neurobiology (Psychiatry) at the CUMC, and Senior Author of the Paper, said: “Many adolescents and young adults who are at high risk for psychosis smoke marijuana regularly or have cannabis use disorder.”
“Yet researchers haven’t studied the effects of marijuana in this population in a rigorous, controlled manner.”
“In this double-blinded, placebo-controlled laboratory study, the researchers looked at the effects of marijuana in six high-risk young adults and six controls, all experienced and current marijuana smokers who were physically healthy.
It indicated that participants smoked half of an active or placebo marijuana cigarette, had psychological and physiological assessments before and after smoking, and then repeated this procedure with the opposite (active or placebo) cigarette.
After smoking active marijuana, both groups had signs of intoxication and increase in heart rate and arousal relative to the placebo.
However, only the high-risk group experienced transient increases in paranoia and anxiety as well as disrupted sensory perception and cognitive performance, after using active marijuana.
Neither group experienced these effects after using the placebo (inactive drug).
“Although this was a small, preliminary study, it suggests that marijuana may affect individuals at high risk for psychosis differently than other marijuana users, by briefly inducing psychotic-like experiences and impairing their cognition,” said Nehal Vadhan, Psychologist and Associate Professor in Psychiatry and Molecular Medicine at Hofstra Northwell School of Medicine, and First Author of the Paper.
“While larger studies are needed to confirm these findings, they may aid clinicians in their guidance to individuals at risk for psychosis about marijuana’s potential effects,” the Paper said.
Jeffrey Lieberman, MD, Chair of Psychiatry at CUMC, and former American Psychiatric Association President, noted that this report “demonstrates the convergent risks of adolescence and expanding cannabis use for the development of psychotic disorders, as well as the opportunity for preventive strategies.”