Underage drinking is pervasive in the U.S. For example, 39% of adolescents in grades 9 through 12 report to consume alcohol in the past month. Furthermore, problematic drinking behavior such as binge drinking (defined as consuming more than four drinks for women and five drinks for men in the past two weeks) and alcohol use disorders emerge in adolescence. Underage drinking brings long-term negative consequences such as permanent damage to brain development, later alcoholism and drug problems, and school drop-outs that affects later education and occupation. For adolescents, family environments such as family conflict and parental monitoring have been studied as risk factors for alcohol use and abuse. However, some people in those environments do not develop drinking problems while other do. Gene and environment interaction (GxE) studies could provide compelling explanations for this, demonstrating that an individual's genotypes strengthen or weaken their susceptibility to the environmental influences. Thus, this study will investigate the effect of interaction between one of a genotype (5-HTTLPR; serotonin transporter linked polymorphic region) and family environments (i.e., family conflict and parental monitoring) on adolescent alcohol use and related problems.

Using ALSPAC data, we will examine our hypothesis that individuals who have at least one short 5-HTTLPR allele and have experienced high levels of parental monitoring would be less likely to be involved in alcohol use than would individuals with only long 5-HTTLPR alleles in the same same environments. Also, we will examine whether individuals with at least one short 5-HTTLPR allele and have experienced high levels of family conflict would be more likely to be involved in alcohol use than would individuals with only long 5-HTTLPR alleles in the same environments. We will statistically control the effects of age, race, gender, puberty, the level of parents' education, and neighborhood context.

The implications of the potential findings are significant for prevention and intervention efforts to curtail prevalent alcohol use among adolescents. Results for the present study will provide information for specific family environments interacting with genetic risk to affect adolescent drinking problems. If family environments affect the relationship between 5-HTTLPR genetic risk and alcohol use in the way we have suggested, the findings will be useful in developing more effective prevention or intervention strategies designed to improve family environments for those individuals whose genotypes make them sensitive to those environments. Overall, the present study will contribute to our understanding of the etiology of adolescent alcohol use and the findings will be valuable for future research directions.