Race/ethnicity and marijuana use in the United States: Diminishing differences in the prevalence of use, 2006-2015

Background: Marijuana use has been decreasing in the past several years among adolescents, though variation in the extent and rate of decrease across racial/ethnic groups is inadequately understood. Methods: The present study utilized nationally-representative data in Monitoring the Future from 2006 to 2015 to examine trends over time in past 30-day marijuana use. We examine whether differences in trends over time by race and ethnicity also differ by individual-level, school-level, and state-level factors. Sample included 131,351 8th grade students, 137,249 10th grade students, and 123,293 12th grade students; multi-level models and difference-in-differences tests were used. Results: In 10th grade, Black students had a positive linear increase in marijuana use (est = 0.04, SE = 0.01, p < 0.001), and the magnitude of the increase was significantly greater than among non-Hispanic White students (est = 0.38, SE = 0.009, p < 0.001). The increase trend among Black students was greater among those in large class sizes. In 12th grade, all racial ethnic groups except non-Hispanic Whites demonstrated a linear increase in prevalence across time. The magnitude of the increase among Hispanic students was greater among those in urban areas and large class sizes. The magnitude of the increase among Black students was greater in states with a medical marijuana law before 2006 (est = 0.06, SE = 0.03, p = 0.02), among other state-level covariates. Conclusion: Together these results suggest that the next stage of public health approaches to reducing the harms associated with adolescent drug use should attend to shifting demographic patterns of use among adolescents and ensure that services and programmatic approaches to adolescent prevention are applied equitably.