Trends in Alcohol and Marijuana Use Among Youth and Young Adults in the United States

Introduction: It is well documented that substance use, including drug and alcohol use, begins in adolescence and regular use is established in young adulthood. With changing regulations, such as the legalization of marijuana, it is important to examine how prevalence of substance use changes in these populations. The purpose of this study is to examine trends in alcohol and marijuana use in a nationally representative sample of United States (US) youth and young adults.

Methods: This study is a secondary data analysis of the National Survey on Drug Use and Health (NSDUH), and examined data from 2008 to 2015. NSDUH uses a multistage sampling design to collect data from a representative sample of individuals (ages 12 and older) from US households. These analyses were limited to youth (aged 12-17 years old) and young adults (aged 18-25 years old). Logistic regression analyses were conducted separately for the outcomes of ever alcohol use, past 30-day alcohol use, ever marijuana, and past 30-day marijuana use stratified by age group, and controlling for sociodemographic factors (i.e., sex, race/ethnicity, and age). Each model included time as an independent variable to test if the prevalence of alcohol or marijuana use has changed over time; time was also modeled as a quadratic variable to test for non-linear changes in the prevalence of alcohol and marijuana use.

Results: Among youth and young adults, there were significant linear decreases in both ever alcohol use (p<.0001) and past 30-day use of alcohol (p<.0001). The prevalence of past 30-day alcohol use among youth decreased from 14% in 2008 to 9% in 2015; among young adults the prevalence decreased from 61% in 2008 to 58% in 2015. Regarding marijuana use, there was a significant non-linear trend in ever use (p=0.0096) and past 30-day use (p=0.0096) among youth, and significant linear increases in ever marijuana use (p=.007) and past 30-day use (p<.0001) among young adults. Among youth, the prevalence of past 30-day marijuana use increased from 6.3% in 2008 to 7.5% in 2011 then decreased to 6.6% in 2015. Among young adults, the prevalence of past 30-day marijuana use increased from 16.6% in 2008 to 19.8% in 2015.

Conclusion: This study shows that while alcohol use may be decreasing, there have been significant changes in marijuana use among youth and young adults in the United States. This study is among the first to document trends in use of these substances in the changing regulatory atmosphere, particularly regarding marijuana use. Further, this study indicates that prevention programs are still needed at both the youth and young adult levels.