Cannabis may be more harmful to teens’ brains than alcohol: study

Montreal — Cannabis may be more detrimental to teen users’ cognitive development than alcohol, and could increase their risk of addiction later in life, findings of a recent study from the University of Montreal suggest.

Researchers sampled nearly 4,000 seventh-grade students from 31 schools in the Montreal area and followed them for four years, starting in 2012. The students were assessed annually on alcohol and cannabis use, and tested on cognitive processes such as recall memory, perceptual reasoning, inhibition and working memory. The researchers also studied vulnerability, as well as concurrent and lasting effects of cannabis on cognition.

The students’ vulnerability to cannabis and alcohol use was associated with generally lower performance in all areas of cognition tested. “However, further increases in cannabis use, but not alcohol consumption, showed additional concurrent and lagged effects on cognitive functions,” senior author and researcher Patricia Conrod, a clinical psychologist and professor of psychiatry at the University of Montreal, said in an Oct. 3 press release.

Especially concerning, Conrod pointed out, was that the findings also linked cannabis use to lasting effects on inhibitory control, a risk factor for other addictive behaviors. This “might explain why early onset cannabis use is a risk factor for other addictions,” Conrod said in the release.

“Some of these effects are even more pronounced when consumption begins earlier in adolescence,” added co-author and Ph.D. student Jean-François G. Morin.

The study was published online Oct. 3 by the American Journal of Psychiatry.