A new study examined longitudinal trends in marijuana use in adolescence by race/ethnicity in the U.S. using a socioecological perspective. Data from the Monitoring the Future study (MTF), a nationally representative sample of eighth-, 10th-, and 12th-grade students, from the years 2006 through 2015 were examined (N > 390,000). Measures included in this analysis were self-reported past 30-day marijuana use, individual factors (race/ethnicity, gender, highest level of parental education), as well as school context (class size, public vs. private status) and state context (level medical marijuana laws, state-level demographic characteristics). The authors used multilevel logistic regression to model the prevalence of marijuana use among respondents within each state by year and grade, then used difference-in-difference models to estimate whether the differences in log odds of respondents reporting past-30 day marijuana use differed by race/ethnicity and whether differences by race also differed by individual, school, and state factors. Results indicated there were no differences in log odds of past 30-day marijuana use over time among eighth graders, but significant differences by race/ethnicity were observed for 10th and 12th graders. Across all years, 10th-graders who identified as multiracial had the highest prevalence of marijuana use, while those who identified as Asian had the lowest. In 12th grade, multiracial students had the highest prevalence of use across most years, but rates among Black and Hispanic students increased over time and eventually converged with those of multiracial students. Non-Hispanic Whites were significantly more likely to use marijuana than Hispanic students from 2006-2010; however, after 2010 there was no significant differences in use for any year. For 10th-graders, significant interactions between race/ethnicity (Black vs. White and Hispanic vs. Non-Hispanic White) and class size were observed. Among 12th-graders, the increase in marijuana use for Black students compared to White students was greater in states with a medical marijuana law enacted before 2006 (p = 0.02).
Take away: Monitoring the Future data indicate U.S. adolescents of color had a greater prevalence of past-month marijuana use than their White peers; however, these differences diminished to convergence by 2015. Class size and state-level medical marijuana laws were also found to influence adolescent marijuana use.