E-Cigarette and Cannabis Social Media Posts and Adolescent Substance Use.

Importance: Adolescents are exposed to e-cigarette and cannabis content on social media. Understanding associations of these exposures with use and dual use of these products can guide regulations. Objective: To assess whether adolescent exposure to e-cigarette and/or cannabis content on social media, including posts by various content creators, is associated with e-cigarette, cannabis, and dual use. Design, Setting, and Participants: Two surveys, one longitudinal (study 1, baseline in 2021 to 2022) and one cross-sectional (study 2, fall 2023), were conducted among California high school students who completed questionnaires on computers in classrooms. Exposures: In study 1, the baseline was frequent exposure (weekly or more vs less frequent or none) to e-cigarette and/or cannabis social media posts. In study 2, the exposure (yes vs no) was to e-cigarette and/or cannabis posts from specific sources (friends, celebrities, microinfluencers, e-cigarette and/or cannabis brands, or unknown sources). Main Outcomes and Measures: For study 1, the primary outcome was solo e-cigarette, solo cannabis, or dual use initiation at 1-year follow-up among baseline never-users of e-cigarettes and cannabis. For study 2, the primary outcome was past-month use of e-cigarettes, cannabis, and dual use. Generalized estimating equations models adjusted for sociodemographic characteristics, mental health, other tobacco product use, social media use, and social environment. Results: In study 1, of 4232 adolescents (mean [SD] age, 17.0 [0.6] years; 2205 female [52.1%]), 968 (22.9%) reported frequent baseline exposure to e-cigarette posts and 507 (12.0%) reported exposure to cannabis posts on social media, broadly; 567 (13.4%) were frequently exposed to e-cigarette posts specifically on TikTok. Frequent exposure to cannabis social media posts was associated with solo e-cigarette use (adjusted odds ratio [AOR], 1.83; 95% CI, 1.11-3.01), solo cannabis use (AOR, 1.60; 95% CI, 1.07-2.38), and dual use (AOR, 1.71; 95% CI, 1.11-2.63) initiation at 1-year follow-up. Frequent exposure to e-cigarette posts on TikTok was associated with solo cannabis use (AOR, 1.74; 95% CI, 1.17-2.58) and dual use (e-cigarette and cannabis) initiation (AOR, 1.78; 95% CI, 1.19-2.66). In study 2, of 3380 adolescents (mean [SD] age, 17.0 [0.6] years; 1840 female [54.4%]), 195 (5.8%) were exposed to microinfluencer e-cigarette posts, and 152 (4.5%) were exposed to microinfluencer cannabis posts; 151 (4.5%) were exposed to friends' e-cigarette posts, and 161 (4.8%) were exposed to friends' cannabis posts. Exposure to e-cigarette (AOR, 2.67; 95% CI, 1.55-4.59) and cannabis (AOR, 2.14; 95% CI, 1.15-4.00) microinfluencer posts was associated with past-month cannabis use. Exposure to friends' e-cigarette posts was associated with past-month dual use (AOR, 2.53; 95% CI, 1.24-5.19), whereas exposure to friends' cannabis posts was associated with past-month cannabis use (AOR, 3.35; 95% CI, 1.94-5.78) and dual use (AOR, 2.46; 95% CI, 1.28-4.71). Conclusions and Relevance: In this survey study of California adolescents, exposure to e-cigarette or cannabis posts was associated with adolescent e-cigarette, cannabis, or dual use. Improvement of social media community guidelines and greater policy attention to co-use and marketing of e-cigarettes and cannabis may help prevent youth substance use.