The protective role of physical activity on adolescent smoking progression.

CS05-02

Adolescence represents an important developmental period whereby lifetime smoking habits are established. Despite the public health significance of smoking among adolescents, our understanding of the factors that protect against smoking progression in this population is limited. To fill this gap we conducted a longitudinal cohort study of over 1,000 adolescents followed from ages 14-18 years. Social, psychological, and genetic, determinants were measured. Latent growth modeling indicated that physical activity reduced the odds of adolescent smoking initiation and progression by 50%. Further, several distinct developmental trajectories of team sport participation were identified through Growth Mixture Modeling. Adolescents with decreasing or erratic team sport participation trajectories across mid to late adolescence were almost three times more likely to regularly smoke in late adolescence compared to adolescents belonging to a high team sport trajectory. Thus, physical activity appears to be protective against adolescent smoking progression. The results suggest that physical activity might be an important intervention component for youth smoking prevention programs. Although the mechanisms by which physical activity impacts smoking progression are not understood, preliminary analyses indicate that depression symptoms explain, in part, the protective effects of physical activity on adolescent smoking progression. That is, physical activity manages depressive symptoms, and lower depressive symptoms tend to be associated with less progression along the adolescent smoking uptake continuum. Preliminary analyses also indicate that gender and race do not significantly moderate the relationship between physical activity and smoking. That is, males and females, and Caucasians and non-Caucasians are equally likely to benefit from the protective effects of physical activity on smoking behavior. Complex bio-behavioral models involving mediated and moderated effects have also been evaluated. These analyses indicated that team sport participation buffers the effect of smoking risk genotypes [dopamine re-uptake transporter (SLC6A3) and the dopamine D2 receptor (DRD2)] on adolescent smoking progression and that the buffering effects of team sport were due to physical activity associated with team sport participation. Thus, team sport and physical activity might be especially beneficial for youth with dopaminergic genotypes associated with the risk of smoking. Future research should identify the amount of physical activity needed to protect against adolescent smoking and determine the optimal time to deliver such an intervention. In addition, future research should investigate other potential mediators and moderators of the physical activity-smoking relationship. This line of inquiry will inform youth smoking prevention efforts (a) by elucidating intervention targets or variables that help explain the protective effect of physical activity on adolescent smoking progression, and (b) by identifying adolescents most likely to benefit from a prevention intervention that incorporated physical activity.