The growing transition from lifetime marijuana use to frequent use among 12th grade students: U.S. National data from 1976 to 2019.

Background: More United States adolescents now report high-frequency marijuana use than similar use levels of alcohol or tobacco. Increased high-frequency use raises questions such as (a) is frequent use likelihood growing among adolescents who experiment with use? (b) Is such change observed equally across sex and racial/ethnic subgroups? (c) Have sociodemographic and other covariate associations with frequent use changed over time?

Methods: Data were obtained from 649,505 12th grade students participating in the cross-sectional, nationally-representative Monitoring the Future study from 1976 to 2019. Historical trends were modeled for any and frequent (20+ occasions) past 30-day marijuana use among all students and lifetime users, and lifetime user sex and racial/ethnic subgroups. Multivariable logistic regression estimates from 1989 to 1993 (lowest prevalence years) versus 2015-2019 (most recent years) were compared to examine covariate association changes with frequent use.

Results: Among all students, recent linear trends in any and frequent marijuana use were not significantly different from zero (0.023 [SE 0.156] and 0.036 [0.073], respectively); frequent use among lifetime users increased (0.233 [0.107], p = 0.048). Among lifetime users, the increase was stronger for male than female students, and for minority versus White students. Significant association changes with race/ethnicity, parental education, and perceived risk were observed.

Conclusions: The proportion of adolescent lifetime marijuana users reporting current frequent marijuana use increased, and is now at near-record levels. Increases were particularly strong among males and minority students. There appears to be an increasing likelihood that adolescents who experiment with marijuana use may progress to frequent use.