Association between broadly defined bulimia nervosa and drug use disorders: common genetic and environmental influences.

OBJECTIVE: Previous research has shown an association between bulimia (BN) and drug use disorders (DUD). The purpose of the present study was to investigate possible influences on the comorbidity between BN and DUD.

METHOD: Participants included 490 monozygotic and 354 dizygotic female twins and 930 females from opposite sex pairs. Multiple logistic regression analyses were used to test shared correlates and mediators. Bivariate twin analyses were used to investigate the contribution of genes and environment to the correlation between BN and DUD.

RESULTS: Depression, neuroticism, and childhood sexual abuse (CSA) mediated the association between BN and DUD regardless of which disorder was used as the dependent variable. Analyses also indicated genetic and nonshared environmental overlap between BN and DUD.

CONCLUSION: The association between BN and DUD is due mostly to overlapping genetic influences with a smaller contribution from nonshared environment. Depression, neuroticism, and CSA are likely important shared correlates.