PROJECT 2 Abstract Although the literature on nicotine addiction is extensive, the various mechanisms by which an adolescent is exposed, experiments, and ultimately becomes addicted to a nicotine product, have not been studied in a comprehensive manner. There are studies focusing on the biological effects of nicotine on the brain; the social pressures confronting adolescents; and demographic and environmental factors such as race, gender, social norms, socioeconomic status, and education, among others. However, no study has investigated how the interactions among these factors influence an adolescent to start or quit using nicotine. This project proposes to develop a novel comprehensive agent-based model of nicotine addiction among adolescents and young adults, including the influence of environmental, social, and biological factors on individuals' behaviors towards nicotine products (Aim 1). Use the model to explore potential pathways of nicotine addiction among adolescents and young adults under different nicotine product mix availability, and the short-term consequences of potential regulatory actions over such products, such as reducing nicotine in combustible tobacco products to non-addictive levels but allowing higher levels of nicotine in non-combustible nicotine delivery products (Aim 2). Project the likely long-term consequences of nicotine addiction among adolescents and young adults, including tobacco-use-attributed premature deaths and life-years-lost, and long-term nicotine dependence (Aim 3). This project will focus on Addiction, Behavior, Impact Analysis and Health Effects as Scientific Domains (RFA-OD-22-04).