Substance use among American adolescents and adults remains a serious public health concern. According to the most recent National Survey on Drug Use and Health1
, rates of substance use during the past 30 days among individuals aged 12 and older were: 51.9% (alcohol); 23.7% (binge drinking); 23.3% (cigarettes); and 6.6% (marijuana). Data from Monitoring the Future indicate that substantial proportions of 12th
graders report current alcohol (44%), cigarette (20%), and marijuana (21%) use, and binge drinking (27%).2
Given the prevalence of substance use behaviors and their considerable health and social consequences1,3,4–9
, developing effective prevention and intervention programs to reduce these behaviors is of high priority. Comparing developmental trajectories of different substance use behaviors and examining gender and racial/ethnic differences in these trajectories may provide insights into critical periods and help to identify target populations for prevention and intervention programs.
Longitudinal studies across adolescence demonstrate increases in substance use from early to late adolescence.10–15
Research focusing on adolescence to young adulthood has found that levels of substance use increase during middle/late adolescent years, peak around early or middle 20s, and then decline thereafter.16–18
However, the samples used in many of these prior longitudinal studies were not nationally representative, limiting generalizability.11,13–17
Of the longitudinal studies that have used nationally representative samples10,12,18
, most have focused solely on changes in substance use across adolescence10,12
, or between late adolescence and young adulthood.18
Thus, nationally representative longitudinal studies examining substance use patterns from early adolescence through adulthood are lacking. Moreover, studies investigating gender and racial/ethnic differences in developmental patterns of substance use from early adolescence to young adulthood are scarce.
National statistics1, 2
and cross-sectional studies19–21
have consistently supported higher mean-levels of substance use in males than in females. However, longitudinal studies have found that girls report higher or similar levels of substance use than boys during early adolescence, while boys have greater increases in substance use over time, and therefore exhibit higher levels of substance use during middle and late adolescence.10,11,14
These findings highlight the need to explore gender differences in substance use more explicitly using a developmental perspective across a longer period of time (i.e. from early adolescence to young adulthood).
Previous national surveys1,2
and other cross-sectional studies19,21–24
have provided evidence for racial/ethnic differences in mean levels of substance use. Caucasians generally report the highest levels of substance use, followed by Hispanics and African Americans, while Asians report substantially lower levels of substance use than other racial/ethnic groups. While a handful of longitudinal studies have provided evidence for racial differences in trajectories of substance use (e.g., African Americans have lower initial levels and lower increasing rates of substance use than their Caucasian counterparts), these comparisons have primarily been made without considering other racial/ethnic minority groups. In addition, longitudinal research investigating racial/ethnic variations in changes in substance use have generally been focused on adolescence, and have not systematically evaluated differences in trajectories at later developmental periods.11, 25–27
Finally, previous studies have rarely examined patterns of alcohol use, binge drinking, smoking, and marijuana use simultaneously. Consequently, it remains unclear whether developmental trajectories of substance use, and gender and racial/ethnic differences in these patterns, differ across forms of substance use. Although one prior study that compared developmental patterns of alcohol use, smoking, and marijuana use identified smoking as the most persistent substance use behavior with the smallest gender differences17
, this study was based on retrospective and non-nationally representative data.
To address these limitations, the current study explores developmental trajectories of four of the most prevalent substance use behaviors (i.e., alcohol use, heavy drinking, smoking, and marijuana use) in a large, nationally representative longitudinal sample ranging in age from 12 to 34. Our primary aim is to investigate developmental trajectories of substance use from early adolescence to young adulthood, and to examine gender and racial/ethnic (Hispanics, Non-Hispanic Caucasians, African Americans, Asians) differences in these trajectories. In addition, developmental patterns of substance use, as well as gender and racial/ethnic differences in these patterns, are compared across different forms of substance use.