Effect of team sport participation on genetic predisposition to adolescent smoking progression.

CONTEXT There is much to be learned about why some adolescents progress to a regular smoking habit and others do not. OBJECTIVE To evaluate whether (1) team sport participation buffers the effect of having 2 smoking risk genotypes (the dopamine reuptake transporter [SLC6A3] and the dopamine D(2) receptor [DRD2]) or 1 of these risk genotypes vs having none on adolescent smoking progression and (2) the buffering effects of team sports were due to physical activity associated with team sport participation. DESIGN Longitudinal cohort study. Survey data were collected annually from grade 9 to the end of grade 12. Self-report measures included smoking, team sport participation, physical activity, depression, smoking exposure, and alcohol and marijuana use. DNA was collected via buccal swabs. Data were analyzed using latent growth modeling. SETTING Five public high schools in Virginia. PARTICIPANTS A total of 361 students of European ancestry. Main Outcome Measure Smoking progression. RESULTS For adolescents participating in at least 1 team sport, but not for adolescents with no team sport participation, physical activity had a significant negative effect on smoking progression (z = -3.85, P<.001; chi(2)(1,N = 361) = 6.73, P = .009). In addition, having 1 (z = 2.69; P = .007) and 2 (z = 2.22; P = .03) smoking risk genotypes had a positive effect on physical activity. These represented significant between-group effects (chi(2)(1,N = 361) = 6.29, P = .01; chi(2)(1,N = 361) = 3.81, P = .05, respectively). Thus, having 1 or more smoking risk genotypes was related to higher levels of physical activity, which, in turn, was related to lower levels of smoking progression for adolescents participating in at least 1 team sport but not for adolescents with no team sport participation. CONCLUSIONS This study provides the first evidence of an interaction between environmental influences and specific genes on adolescent smoking and may promote an understanding of important protective relationships in the environment.