title: Drinking expectancies and motives: a genetic study of young adult women.
abstract: BACKGROUND
  Constructs such as drinking expectancies (beliefs regarding the effects of alcohol) and motives (drinking alcohol to achieve a valued end) have been shown to be associated with various stages of alcohol use behaviors. However, little is known of the extent to which genetic and environmental influences contribute to individual differences in expectancies and motives.
  
  
  METHODS
  Using data from 3,656 young adult same-sex female twins, we examined the association between measures of drinking expectancies and motives and drinking behaviors. Using twin models, we estimated the extent to which genetic, shared and non-shared environmental factors influenced individual differences in expectancies and motives and also tested whether the extent of the genetic and environmental contributions on expectancies varied across abstainers and users of alcohol.
  
  
  RESULTS
  Expectancies predicted initiation of alcohol use. Both motives and expectancies were associated with frequency and quantity of alcohol consumption and drinks-to-intoxication. There was no evidence for heritable influences on expectancies and enhancement motives, with familial similarity for these traits being due to shared environment. Heritable influences on social, coping and conformity motives ranged from 11% to 33%. When expectancies were stratified by alcohol use, significant heritable influences (31-39%) were found for cognitive-behavioral impairment and risk-taking/negative self-perception (RT/NSP) in abstainers only, while environmental influences contributed to familial variance for other measures of expectancies in alcohol users.
  
  
  CONCLUSIONS
  Environmental influences (both familial and individual-specific) shape alcohol expectancies, while heritable influences may predispose to motives for drinking. Individual differences in expectancies are moderated by alcohol use, suggesting that sources of individual differences in expectancies may vary in drinkers versus abstainers.
authors.affiliation: Washington University School of Medicine, Department of Psychiatry, St Louis, MO 63110, USA. arpana@wustl.edu
authors.forename: Arpana
authors.initials: A
authors.lastname: Agrawal
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Dick
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.forename: Pamela A F
authors.initials: PA
authors.lastname: Madden
authors.forename: M Lynne
authors.initials: ML
authors.lastname: Cooper
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Sher
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Heath
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology / Q000235:genetics / Q000523:psychology*; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D009042:Motivation; D012931:Social Environment; D014429:Twins, Dizygotic / Q000523:psychology; D014430:Twins, Monozygotic / Q000523:psychology