Introduction: E-cigarette use remains a controversial topic in public health and medicine. Historically, cigarette smoking was identified as a gateway to marijuana use among adolescents. Recently, the prevalence of adolescent cigarette smoking has declined, but that of e-cigarette use continues to increase. As e-cigarettes eclipse cigarettes among adolescents, e-cigarette use may predispose adolescents to marijuana use. This study examines the relationship between e-cigarette use and marijuana use in a national sample of adolescents who have never smoked conventional cigarettes.
Methods: A national sample of 8th and 10th grade never-smokers of conventional cigarettes (N=12,743) was obtained from 2014-2015 Monitoring the Future surveys. The dependent variable was past 30-day marijuana use (dichotomized Yes/No), and the independent variables were past 30-day e-cigarette use (dichotomized Yes/No), perceived availability of marijuana, peer marijuana use, parental monitoring, and religiosity. A multivariable logistic regression was conducted with marijuana use regressed on e-cigarette use, and other independent variables while controlling for covariates such as paid employment, risk-taking propensity, and sociodemographic variables. Additional regression analysis was conducted on e-cigarette users only.
Results: Among adolescent never-smokers of conventional cigarettes, 5.2% and 5.6% had used marijuana and e-cigarettes, respectively, in the past 30 days. Among never-smokers who are current e-cigarette users, 24.2% had used marijuana at least once in the past 30-days, compared to 3.9% of non-e-cigarette users. Logistic regression analyses showed that e-cigarette users were three times more likely than non-users to be current marijuana users after adjusting for other variables. Perceived availability of marijuana and peer marijuana use increased the likelihood of marijuana use, while parental monitoring and religiosity were protective against marijuana use. Among e-cigarette users, the predictors of marijuana use were peer marijuana use and perceived availability of marijuana.
Conclusion & Implications: A significant proportion of adolescents who have never smoked conventional cigarettes are current marijuana users. Among these adolescents, e-cigarette use is associated with a threefold increase in odds of marijuana use, suggesting a link between e-cigarette and marijuana use that is independent of conventional cigarette smoking. Among e-cigarette users, peer marijuana use and perceived availability of marijuana are particularly predictive of marijuana use and are potential foci for targeted interventions focused on reducing dual e-cigarette and marijuana use among adolescents
