Grant Number:	3R01CA290828-02S1 Interpret this number
Primary Investigator:	Thrasher, James
Organization:	University Of South Carolina At Columbia
Project Title:	Building Stochastic Actor-Oriented Models to Investigate Social Network Influences on Youth Nicotine Product Use Transitions and to Simulate Different Intervention Effects Across Contexts
Fiscal Year:	2025

In the United States and Mexico, teens’ combustible cigarette (CC) use has declined in recent years, yet ecigarette (EC) use has increased. CC&EC initiation commonly occurs in adolescence, when peer influence is particularly strong. Prior research finds that teen CC&EC use is similar among best friends, yet the mechanisms leading to this clustering of behavior are unclear. Friends can spur changes in each other’s behavior (influence), but peers with similar risk for and use of CC&ECs can become friends (selection). Existing research on peer influence and CC use is almost exclusively based on best friendship networks, but new research suggests that more intimate connections like friendship relations (strong ties) are empirically different from comparatively less intimate, and now highly ubiquitous, online interaction networks (weak ties), such as people with whom teens interact via social media. Furthermore, recent school-based interventions have successfully leveraged interaction networks, not friendship networks, to reduce teen bullying and CC use. Mexico is a unique environment for studying these network mechanisms because EC marketing is not permitted, potentially raising the importance of online interaction networks for communicating pro-EC messages. This study will collect data through 5 surveys over 2 years from a cohort of Mexican high schoolers in Tijuana, which may be more exposed to US-based tobacco marketing and products because of its location on the US border, and Guadalajara, where such exposures are less likely. We will separately measure their (best) friendship and online interaction networks, measure teens’ preferences for CC&EC products that interventions can influence (e.g., access to flavored products) using discrete choice experiments (DCEs), and evaluate initiation and progression of CC&EC use. Stochastic Actor-Oriented Models (SAOMs), a family of agent-based models designed for statistical inference, will be used to analyze the co-evolution between online and best friends dynamics and CC&EC use dynamics, (e.g., exclusive vs. sequential vs concurrent CC&EC use). Our SAOMs will incorporate DCE-derived individuallevel preferences (i.e., CC vs. EC; tobacco vs. other flavors), which the agent-based modeling literature in health has not done to date. These SAOMs will serve as a virtual laboratory for evaluating the relative effectiveness of different network-based and other interventions to reduce teen CC&EC use. Workshops with stakeholder groups (e.g., students, school administrators) will solicit feedback about the effects, feasibility, and adoption of various interventions we can simulate. We will harmonize our surveys with and rigorously compare our results with those from a cohort of high schoolers in the US, where network data are similar but less complete due to much lower student participation (<50%) than we can achieve in Mexico (>90%) with strong support from school system administrators. Our project involves sharing results – including those related to online interaction networks that are only captured in the Mexico survey - with an NIH-funded research Center for evaluating different interventions on American youths’ use of nicotine products, including their impact on Americans’ health overall.





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