Regular cannabis use linked to poorer academic performance

Young people who smoke cannabis regularly achieve lower grades at school and are less likely to want to pursue higher education than those who do not, according to a major new study in Canada.

Published in the Journal of School Health, it found that users were four times more likely to skip classes and around two to four times less likely to complete their homework.

Researchers from the University of Waterloo in Ontario compared data from 26,475 school pupils aged 13-18 over a three-year period.

Greater risk

Karen Patte, lead author of the paper, said: “We found that the more frequently students started using the drug, the greater their risk of poor school performance and engagement.”

In its conclusion, Patte’s report stated that risk perceptions of cannabis use “have substantially declined” and this was likely to worsen if cannabis legalisation went ahead.

“Countering implied messages of harmlessness, and raising awareness of links with academic non-achievement, are essential considering these trends”, she said.


Canada’s Prime Minister Justin Trudeau introduced a Bill last month to legalise the recreational use of cannabis.

The study found that students who used cannabis daily were 50 per cent less likely to say they wanted to go to university than those who did not use it.

Scott Leatherdale, a professor in the School of Public Health and Health Systems, said: “With marijuana legalisation on the horizon, it’s critical we understand these risks in order to promote successful transitions into adulthood for our youth.”