First use of cannabis compared to first use of alcohol and tobacco: Associations with single and poly-substance use behavior (2023)

Introduction: Young adults report high rates of current cannabis use. The proliferation of legalized cannabis in the US has led to greater access and availability, causing cannabis to become the new "gateway" drug. This study examined the prevalence of trying cannabis before alcohol or tobacco and the association of initiation with cannabis first with single and poly-substance use in young adults.
Methods: Data were analyzed from young adults (n=8062) in Waves 1 through 5 (2013-2019) of the Population Assessment of Tobacco and Health study who had ever tried alcohol, cannabis, or tobacco and provided age at first use of these substances. Weighted multivariable models examined associations between cannabis initiation before, at the same age, or after initiating alcohol or tobacco use with past 30-day substance use (alcohol, cannabis, tobacco, poly-substance use) in a subsequent wave (Waves 2-5).
Results: Initiating cannabis before alcohol and tobacco (6%) was rare. In adjusted regression models, initiating cannabis before alcohol and tobacco was associated with increased odds of past 30-day cannabis use, past 30-day tobacco use, and past 30-day polysubstance use and decreased odds of past 30-day alcohol use. Initiating cannabis at the same age as either alcohol or tobacco, or trying cannabis after these substances was associated with increased odds of all substance use outcomes.
Conclusions: Cannabis initiation before alcohol and tobacco is uncommon and may even protect against future alcohol use. Deterring cannabis initiation with multiple substances could have public health benefits.