Simultaneous Alcohol and Marijuana Use Among College Students in the United States, 2006-2019

Background and Purpose: Previous research shows that most users of alcohol and marijuana use these simultaneously. Recent evidence suggests that among college students in the United States (US), the prevalence rates of alcohol misuse decreased while rates of marijuana use increased in recent years. Given the opposite trends in alcohol and marijuana use, it is unclear whether simultaneous alcohol and marijuana (SAM) use is on the rise or decline among college students. SAM use exposes college students to more adverse consequences than single-substance and concurrent use, including blackouts, impaired control, driving under the influence, vomiting, psychical dependence, risk behaviors, and cognitive, social, academic, and occupational consequences. Despite its importance, there is no nationally representative study on the recent trends of SAM use among US college students. The present study aimed to examine the trends, prevalence, and psycho-social-behavioral correlates of SAM use among US college students, using nationally representative data from the National Survey on Drug Use and Health (NSDUH).

Method: We used data from the 2006-2019 NSDUH and the analytic sample was limited to the 55,669 full-time college student respondents (ages 18-22). Using logistic regression analysis, we assessed trends in SAM use prevalence and examined sociodemographic and psycho-social-behavioral correlates of SAM use.

Results: The proportion of US college students who reported SAM use increased significantly from 8.13% (2006-2010) to 8.44% (2015-2019). However, examination by race/ethnicity revealed that the increasing trend was largely driven by Black/African American (AA) college students, whose SAM use prevalence increased significantly from 5.50% (2006-2010) to 9.30% (2015-2019), reflecting a 69.09% increase. SAM use rates did not change significantly among other racial/ethnic groups. Significant SAM use trend increases were also observed among college students who (a) were 21 (21.68% increase) and 22 years old (15.39% increase), (b) identified as female (23.28% increase), (c) had household incomes of <$20,000 (15.87% increase) and $20,000-$39,999 (17.16% increase), and (d) resided in small metro areas (11.49% increase). SAM use was significantly associated with major depressive episodes, serious psychological distress, higher risk propensity, easy access to marijuana, drug selling, theft, violent attack, driving under the influence of alcohol and marijuana, binge drinking, illicit drug use (other than marijuana), alcohol use disorder, and marijuana use disorder. Higher religiosity and perceiving great risk with smoking marijuana and having 5 or more alcohol drinks 1-2 times/week were associated with a lower likelihood of SAM use.

Conclusions and Implications: This study uncovered an increasing trend of SAM use among US college students, calling for more research and public health interventions in this area. Specifically, between 2006 and 2019, there was an upward trend of SAM use among Black/AA college students, while trends among college students from other racial/ethnic groups remained generally stable. In 2019, Black/AA college students replaced White students as the racial/ethnic subgroup with the highest prevalence of SAM use (13%). Besides Black/AA college students, other subgroups that warrant more attention include college students who are female, above the legal drinking age, have a lower than $20,000 household income, and reside in small metropolitan areas.