High school students’ grades suffer when they start consuming cannabis on the regular, according to a new study that seems to reaffirm the importance of full legalization and regulation.  

The study by University of Waterloo researchers also found that after students start using cannabis, they tend to become less interested in scholarly pursuits.

Survey answers from 25,000 students across Canada revealed that students who consume cannabis at least once a month end up skipping class and failing to complete homework more often than those who don't use cannabis – even if they hadn’t been engaging in those behaviors beforehand.

The findings also showed that students who consume cannabis are about half as likely as other students to get good grades, and considerably less likely to value the importance of marks. These students also reported being less interested in pursuing post-secondary education, while this same effect was not found in students who started drinking alcohol.

“The findings support the importance of preventing and delaying the initiation of marijuana use among adolescents,” said Scott Leatherdale of Waterloo’s School of Public Health and Health Systems.

The research team emphasized the importance of understanding the effects of cannabis on young Canadians ahead of the government’s plan to legalize the substance by July 1, 2018. Federal decision-makers have proposed the minimum age of consumption be set at least 18, but individual provinces will be able to raise it at their discretion.

h/t CTV