Toronto: While both alcohol and marijuana misuse are known to be associated with impairments in learning, memory, attention and decision-making, as well as with lower academic performance, a new study claimed that cannabis use has lasting effects on cognitive skills in teenagers than alcohol.

The findings, led by researchers at Universite de Montreal, showed cannabis affected cognitive functions such as perceptual reasoning, memory recall, working memory and inhibitory control. Moreover, these increased with cannabis use and also were long-lasting compared to alcohol. “Increases in cannabis use, but not alcohol consumption, showed additional concurrent and lagged effects on cognitive functions such as perceptual reasoning, memory recall, working memory and inhibitory control,” said Patricia Conrod, from the varsity.

“Of particular concern was the finding that cannabis use was associated with lasting effects on a measure of inhibitory control, which is a risk factor for other addictive behaviours, and might explain why early-onset cannabis use is a risk factor for other addictions,” added Jean-Francois G. Morin, a doctoral student at Montreal.

“Some of these effects are even more pronounced when consumption begins earlier in adolescence,” Morin added. For the study, published in the American Journal of Psychiatry, the team followed a sample of 3,826 Canadian high school students from 7th to 10th grade over a period of four years.

In a context where policies and attitudes regarding substance use are being reconsidered, this research highlights the importance of protecting youth from the adverse effects of consumption through greater investment in drug-prevention programmes.

“While this study did not detect effects of teenage alcohol consumption on cognitive development, the neurotoxic effects may be observable in specific subgroups differentiated based on the level of consumption, gender or age,” Morin said.