DRD2 and DRD4 in relation to regular alcohol and cannabis use among adolescents: Does parenting modify the impact of genetic vulnerability? The TRAILS study

Abstract Aims The aims of the present study were to determine the direct effect of DRD2 and DRD4, as well as their interaction with parenting (i.e. rejection, overprotection and emotional warmth), on the development of regular alcohol and cannabis use in 1192 Dutch adolescents from the general population. Methods Information was obtained by self-report questionnaires. Perceived rejection, overprotection and emotional warmth were assessed at age 10–12. Regular alcohol and cannabis use were determined at age 15–18 and defined as the consumption of alcohol on 10 or more occasions in the past four weeks, and the use of cannabis on 4 or more occasions in the past four weeks. Models were adjusted for age, sex, parental alcohol or cannabis use, and externalizing behavior. Results Carrying the A1 allele of the DRD2 TaqIA polymorphism, or the 7 repeat DRD4, was not directly related to regular alcohol or cannabis use. In addition, adolescent carriers of these genetic risk markers were not more susceptible to the influence of less optimal parenting. Main effects for parenting indicated that overprotection increased the risk of regular alcohol use, whereas the risk of cannabis use was enhanced by parental rejection and buffered by emotional warmth. Conclusions Our findings do not support an association between DRD2/DRD4 and regular alcohol and cannabis use in adolescents. Given the substance-specific influences of rejection, overprotection and emotional warmth, these parenting factors might be promising candidates for prevention work.