Heritability of binge-eating and broadly defined bulimia nervosa

Background: Using diagnostic information obtained at two different times, w e incorporated error of measurement into structural equation twin models to evaluate the contribution of additive genetic, common environmental, and i ndividual-specific environmental factors to the liability to binge-eating a nd broadly defined bulimia nervosa (BN). We also evaluated the validity of the equal environment assumption (EEA) with reference to these two phenotyp es. Methods: We interviewed 1897 female twins (including both members of 854 tw in pairs) from a population-based register about their lifetime history of binge-eating and of broadly defined BN twice, approximately 5 years apart. Results: The reliabilities of a lifetime history of binge-eating (kappa = . 34) and of broadly defined BN (kappa = .28) were low. Based on single inter views, the heritability of binge-eating was estimated to be 50% and broad B N 60%, with the remaining variance attributable to individual-specific envi ronment. Common environmental influences had no effect on liability to eith er trait. By combining information from two interview waves and thereby inc orporating error of measurement into a structural equation model, the estim ated heritability of the latent vulnerability to binge-eating (82%) and bro adly defined BN (83%) increased substantially. Although there were no viola tions of the EEA detected for binge-eating, cosocialization influenced twin concordance for broadly defined BN. Conclusions: Lifetime histories of binge-eating and broadly defined BN appe ar to be highly heritable conditions of low reliability. Biol Psychiatry 19 98;44:1210-1218. (C) 1998 Society of Biological Psychiatry.