Teenagers who smoke marijuana regularly achieve poorer grades at school and risk their chances of going to university, according to a major new scientific study.
A longitudinal study of more than 26,400 pupils in Canada found those who started using marijuana at least once a month were around half as likely to achieve high grades as they were before taking up the habit, and were ultimately less likely to pursue university ambitions.
Marijuana users were also four times more likely to skip classes and two-to-four times less likely to complete their homework and value getting good grades.