Summarize in three sentences: Importance: Polysubstance use is associated with adverse health outcomes; yet little research has attempted to measure changes in polysubstance use and how such trends are motivated by the use of individual substances.

Objective: To estimate population-based trends in heavy alcohol and marijuana use stratified by cigarette smoking status and demographic subgroups, and examine risk factors associated with heavy alcohol and marijuana use among current smokers

Design: Repeated cross-sectional study

Setting: National Survey on Drug Use and Health (NSDUH) from 2002-2020

Participants: 734,061 non-institutionalized US adults aged ≥18 years

Exposures: Current, former, and never smoking status

Main Outcomes and Measures: Prevalence of heavy alcohol use, marijuana use, and concurrent use of heavy alcohol and marijuana. We estimated annual prevalence of use and used multiple logistic regression to examine risk factors of using heavy alcohol and/or marijuana among current smokers.

Results: Among 623,229 participants in 2005-2020 NSDUH, 46.5% were male, 58.9% were between 18-34 years old, and 62.5% were non-Hispanic White. From 2002-2020, the prevalence of heavy alcohol use declined from 8.39% to 7.87%, marijuana use rose from 5.97% to 12.10%, and the prevalence of concurrent use of alcohol and marijuana increased from 1.67% to 2.21% (all P-values <0.05). Among current smokers, higher education attainment and mental illness were associated with increased odds of heavy alcohol use, while  Your response should contain less than 800 words.
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