Estrogen moderation of genetic influences on eating disorder symptoms during gonadarche in girls: Specific effects on binge eating.

The heritability of eating disorder (ED) symptoms increases dramatically across gonadarche in girls. Past studies suggest these developmental differences could be due to pubertal activation of estrogen, but findings have been limited to only one ED symptom (i.e., binge eating). The current study examined whether estrogen contributes to gonadarcheal differences in genetic influences on overall levels of ED symptoms as well as key cognitive symptoms (i.e., weight/shape concerns) that are present across all EDs and are early risk factors for eating pathology. Given that binge eating frequently co-occurs with all of these symptoms, analyses also examined whether estrogen effects exist for overall levels of ED symptoms and body weight/shape concerns after accounting for the known effects of estrogen on genetic risk for binge eating. Participants included 964 female twins (ages 8-16) from the Michigan State University Twin Registry. Overall levels of ED symptoms were assessed with the Minnesota Eating Behavior Survey (MEBS) total score. Weight/shape concerns were assessed with a latent factor modeled using subscales from the MEBS and the Eating Disorder Examination Questionnaire. Estradiol levels were assessed with saliva samples. Twin moderation models were used to examine whether genetic influences on overall levels of ED symptoms and weight/shape concerns differed significantly across estradiol levels. Although initial models suggested modest differences in genetic influences on overall levels of ED symptoms across estradiol levels, these effects were eliminated when binge eating was accounted for in the models. In addition, weight/shape concerns did not show significant moderation of genetic influences by estradiol in models with or without binge eating. Taken together, results are significant in suggesting that individual differences in estradiol levels during gonadarche have a unique and specific impact on genetic risk for binge eating, while other etiologic factors must contribute to increased heritability of cognitive ED symptoms during this key developmental period in girls.