Few high school cannabis users quit on their own, but those who did showed improved attendance and homework completion | Research

The takeaway

Only 14.8% of high school cannabis users reduced their use between grade levels, but students who quit showed significantly better class attendance and homework completion than those who continued using.

School counselors, educators, parents of teens using cannabis, and policymakers designing school-based prevention programs.

Only 14.8% of teen cannabis users reduced use between grades

What the researchers found

Only 14.8% decreased use between grades, with two-thirds making only incremental changes. Cessation rates from daily and weekly use decreased each year. Students who quit had better odds of class attendance (OR=2.48) and homework completion (OR=2.32) compared to continuing users, but still had worse math performance than never-users (OR=0.55).

Why it matters

This large longitudinal study shows that spontaneous cannabis cessation is uncommon among high school students, suggesting most teen users need external support. The academic improvements seen after quitting provide concrete motivation for cessation.

The numbers in context

91,774 observations. 14.8% reduced use between grades. Quitters vs. continuing users: attendance OR=2.48, homework OR=2.32. Quitters vs. never-users: math OR=0.55 for some subcategories. Cessation rates from daily/weekly use declined each year.

How the study worked

Longitudinal analysis of 91,774 linked observations from the COMPASS prospective cohort study of Canadian high school students (Grades 9-12, 2013-2017). Cannabis use change patterns tracked across grade transitions. Academic outcomes (math, English marks, homework, truancy) compared between quitters, continuing users, and never-users.

What this study cannot tell us

Observational data cannot prove that quitting caused academic improvements. Self-reported cannabis use and academic outcomes. Students who quit may differ systematically from those who continue. Canadian sample may not generalize to other countries.

How to read the evidence

Large prospective cohort with longitudinal tracking, but observational design and self-reported data.

When this study was published

2020 study using pre-legalization Canadian data (2013-2017). Provides baseline for evaluating post-legalization cessation patterns.

The bigger picture

The finding that cessation rates decrease each year suggests a narrowing window for intervention. School-based programs that support cannabis reduction early in high school may have the best chance of success.

Questions still open

Would targeted school-based cessation support increase quit rates? Do academic improvements from quitting persist long-term? What distinguishes the minority who spontaneously quit from those who continue?

Common questions

Did quitting cannabis improve grades?

Quitters showed significantly better attendance and homework completion than continuing users. Some math performance improved, but quitters still scored below never-users, suggesting academic recovery may be partial.

Why did so few teens quit on their own?

Only 14.8% reduced use, and cessation rates from daily/weekly use dropped each year, suggesting cannabis use becomes harder to stop without external support as it continues through high school.

Read the original research

Cannabis cessation among youth: rates, patterns and academic outcomes in a large prospective cohort of Canadian high school students.

Health promotion and chronic disease prevention in Canada : research, policy and practice, 40(4), 95-103

View on PubMed ↗Publisher’s paper ↗

Citation

Zuckermann, Alexandra M; Gohari, Mahmood R; de Groh, Margaret; Jiang, Ying; Leatherdale, Scott T. (2020). Cannabis cessation among youth: rates, patterns and academic outcomes in a large prospective cohort of Canadian high school students.. Health promotion and chronic disease prevention in Canada : research, policy and practice, 40(4), 95-103. https://doi.org/10.24095/hpcdp.40.4.01