title: DRD4 and susceptibility to peer influence on alcohol use from adolescence to adulthood.
abstract: BACKGROUND
  The long allele of DRD4 is associated with greater susceptibility to peer influences on alcohol use in young adulthood, but it is unclear whether this increased susceptibility extends to other developmental periods. This study examined the interactive effects of DRD4 polymorphism and friends' alcohol use from adolescence to adulthood.
  
  
  METHODS
  Participants (N = 340; 59% female; 98% White) reported on their own and their friends' alcohol use at four time points between mean ages 17 and 33. Autoregressive cross-lagged models evaluated reciprocal relationships between friends' alcohol use and participants' own alcohol use and frequency of heavy drinking over time. Multigroup modeling tested differences in model paths and covariances across high vs. low risk DRD4 polymorphisms.
  
  
  RESULTS
  Alcohol use at age 33 was predicted by previous friends' alcohol use and correlated with current friends' alcohol use only for carriers of the DRD4 long allele. Regardless of DRD4 genotype, friends' alcohol use at age 17 predicted greater alcohol use and more frequent heavy drinking at age 23. Alcohol use and/or heavy drinking predicted greater friends' alcohol use at later time points for both genotype groups across adolescence and adulthood.
  
  
  CONCLUSIONS
  The long allele of DRD4 is associated with increased susceptibility to peer influences on alcohol use in young adulthood, but not earlier in development. Adults with the long allele of DRD4 may benefit from interventions educating them about this risk and equipping them with strategies to reduce affiliations with and influence of drinking friends.
authors.affiliation: University of Alabama at Birmingham, Department of Psychology, 1720 Second Avenue South, CH415, Birmingham, AL 35294-1170, United States. Electronic address: smrug@uab.edu.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Mrug
authors.affiliation: Emory University, Department of Behavioral Science and Health Education, 1518 Clifton Road NE, Room 514, Atlanta, GA 30322, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Windle
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology* / Q000235:genetics* / Q000523:psychology; D000483:Alleles; D005260:Female; D033062:Friends / Q000523:psychology; D006801:Humans; D008297:Male; D010379:Peer Group; D050638:Receptors, Dopamine D4 / Q000235:genetics*; D055815:Young Adult
chemical_list: C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4
keywords: Alcohol use; DRD4; Gene by environment; G×E interaction; Peer