Does variance in drinking motives explain the genetic overlap between personality and alcohol use disorder symptoms? A twin study of young women.

Background: Genetic risk for alcohol dependence has been shown to overlap with genetic factors contributing to variation in dimensions of personality. Although drinking motives have been posited as important mediators of the alcohol-personality relation, the extent to which the genetic covariance between alcohol use disorder (AUD) symptoms (i.e., abuse and dependence criteria) and personality is explained by genetic factors contributing to variation in drinking motives remains unclear.

Methods: Using data from 2,904 young adult female twins, the phenotypic and genetic associations between personality dimensions (constraint [measured by the Multidimensional Personality Questionnaire; Tellegen A, 1982 unpublished data], conscientiousness, neuroticism, and agreeableness [measured by the NEO-PI; Costa and McCrae, 1985]), internal drinking motives (enhancement and coping motives [measured by the Drinking Motive Questionnaire; Cooper, 1994]), and AUD symptoms were tested.

Results: Significant genetic associations were found between all personality measures and AUD symptoms. Coping motives showed significant genetic overlap with AUD symptoms and most personality measures, whereas enhancement motives were not significantly heritable. Adjusting for coping motives, genetic correlations between AUD symptoms and traits of neuroticism and agreeableness were no longer statistically significant.

Conclusions: Findings suggest that genetic variation in drinking to cope might account for a considerable proportion of the genetic covariance between specific personality dimensions and AUD symptoms.