Changes in gender and racial/ethnic disparities in rates of cigarette use, regular heavy episodic drinking, and marijuana use: Ages 14 to 32

Background: The purpose of this study is to investigate disparities in substance use behaviors across gender and race/ethnicity as a flexible function of age from mid-adolescence through young adulthood. Methods: Using data from the National Longitudinal Study of Adolescent Health, the time-varying effect model (TVEM) was used to examine gender and racial/ethnic differences in the prevalence of cigarette use, regular heavy episodic drinking (HED), and marijuana use as a smooth function of developmental age. Results: Prevalence of cigarette use, regular HED, and marijuana use was higher for males than females overall, although gender differences varied with age. With regard to race, prevalence of each substance was higher for White than Hispanic or Black individuals; these differences increased considerably from ages 16 to 20, particularly for cigarette use. Differences in cigarette use by race/ethnicity were found across age, but were largest at age 18, when cigarette use peaks for White individuals, but continues to climb throughout the 20s among Hispanic and Black individuals. Conclusions: These results suggest that substance use, particularly for certain population subgroups, increases past early adolescence. Disparities in substance use behaviors fluctuate considerably throughout adolescence and young adulthood, suggesting that targeted intervention programs are more critical at particular ages. These findings also demonstrate that TVEM can advance our understanding of health risk behaviors and their correlates across developmental time.