Age, period and cohort effects on heavy episodic drinking among adolescents in Ontario, Canada: 1999–2023

<i>Background:</i> Heavy episodic drinking (HED) poses significant risks during adolescence. Despite declining prevalence over years, it remains unclear whether these trends are influenced by historical changes or are independent of age and birth cohort effects.<i>Objectives:</i> To investigate the age-period-cohort (APC) effects on HED among adolescents in Ontario, Canada.<i>Methods:</i> Data drawn from the Ontario Student Drug Use and Health Survey (OSDUHS) from 1999 to 2023. OSDUHS is a repeated cross-sectional survey of students in grades 7 through 12 attending publicly funded schools in Ontario, Canada. The survey used a stratified two-stage cluster sampling method, including 103,977 adolescents (50.9% females) aged 12-18 years.<i>Results:</i> The observed prevalence of HED in the past 30 days declined from 27% in 1999 to 9.6% in 2023. In the pooled sample, HED increased from 2.2% at age 12-41.6% at age 18, with a notable divergence in HED rates between males and females at ages 17 and 18. APC analysis revealed that adolescents born in the early 1990s (cohort effect) were nearly twice as likely to engage in HED as those born in 2000 (RR = 1.78, 95%CI: 1.63-1.95). The strongest period effect was evident in 2000, with odds of HED higher than 2015 (RR = 1.55, 95%CI: 1.39-1.72), followed by a peak in 2018 and a decline in recent periods.<i>Conclusions:</i> Teen binge drinking has declined over time, with newer generations drinking less. These shifts may reflect changing social norms and lifestyle preferences. Identifying the most affected age and cohort groups can guide targeted prevention.