Conrod said her team took a “big data” approach to the study. They looked at 3,826 teens starting from seventh grade from 31 Montreal-area schools over the course of four years. The students who participated sent back annual reports that documented their level of alcohol and marijuana use. The researchers also gave the teens cognitive tests to gauge the teens’ working memory, perceptual reasoning, recall memory, and inhibition.
To make sure they got the most honest responses from the students, these reports were confidential. Parents and teachers, not allowed.
The study authors reported that teens who used cannabis more often than others had cognitive function changes that appeared “to be more pronounced than those observed for alcohol.”
Conrod said the results should be a cautionary tale to teens as they contemplate marijuana use at a young age.
“Our findings suggest young people should do everything they can to delay the