Different trajectories of adolescent alcohol use: Testing gene-environment interactions

Background: Transitions into heavy alcohol use often already take place during adolescence and are likely to be both genetically and environmentally determined. Therefore, in a 6-wave longitudinal study, we examined the effects of DRD2 Taq1A and OPRM1 A118G genotypes and the interaction with parental rule-setting on different groups of adolescent drinkers. Methods: Growth mixture modeling resulted in 3 distinct groups of adolescent drinkers: light drinkers (n = 346), moderate drinkers (n = 178), and heavy drinkers (n = 72). Results: Multinomial regression showed that moderate drinkers carried the OPRM1 G allele and received lower levels of parental rule-setting significantly more often than the light drinking group. No other significant main effects of DRD2, OPRM1, and rule-setting were found. The interaction between OPRM1 genotype and parental rule-setting significantly distinguished the heavy drinkers from the light (p < 0.001) and moderate groups (p = 0.055): Particularly, the alcohol use of OPRM1 G allele carriers was affected by parental rule-setting, while AA genotype carriers remained largely unaffected by parental rules. Conclusions: Findings showed that different trajectories of adolescent drinking are preceded by a gene-parenting interaction. These results concur with Belsky's theory of plasticity (2009), as well as with Shanahan and Hofer's typology of a controlling and restricting gene-environment interaction (2005).