Impulsivity has emerged as a critical personality trait contributing to individual differences in the development of binge eating, and research suggests that negative urgency (i.e., the tendency to engage in rash action in response to negative affect) is a particularly important form of impulsivity for these behaviors. However, studies investigating the extent to which genetic and/or environmental influences underlie the effects of negative urgency on binge eating are lacking. Moreover, it remains unclear whether associations between negative urgency and binge eating are simply due to the well-established role of negative affect in the development/maintenance of binge eating. Study 1 addressed these gaps by examining phenotypic and etiologic associations between trait levels of negative urgency, negative affect, and binge eating in a sample of 444 same-sex female twins from the Michigan State Twin Registry. Negative urgency was significantly associated with two well-validated measures of binge eating tendencies, even after controlling for the effects of negative affect. Genetic factors accounted for the majority (62-77%) of this phenotypic association, although a significant proportion of this genetic covariation was due to genetic influences in common with negative affect. Non-shared environmental factors accounted for a relatively smaller (23-38%) proportion of the association between negative urgency and binge eating, but these non-shared environmental effects were independent of negative affect. Findings suggest that emotion-based rash action, combined with high levels of negative affect, may increase risk for binge eating, and that this likely occurs through both genetic and environmental mechanisms.Full article available at: http://psycnet.apa.org/journals/abn/ Study 2 considered whether, in addition to having main effects, negative urgency might interact with other well-established risk factors for binge eating. Within-person changes in estradiol and progesterone predict changes in binge eating tendencies across the menstrual cycle. However, all women have menstrual-cycle fluctuations in hormones, but few experience binge eating. Personality traits, such as negative urgency, may be critical individual difference factors that influence who will engage in emotional eating in the presence of a vulnerable hormonal environment. Self-reports of emotional eating and saliva samples for hormone measurement were collected for 45 consecutive days in adolescent and young adult females (N=239). Negative urgency and negative emotionality were measured once and were examined as moderators of hormone-emotional eating associations. Consistent with prior research, within-person changes in the interaction between estradiol and progesterone predicted emotional eating symptom changes. However, negative urgency and negative emotionality did not interact with changes in estradiol, progesterone, or the estradiol-progesterone interaction to predict changes in emotional eating across the menstrual cycle. Future research should consider additional factors, other than the two personality traits examined, that may account for individual differences in within-person associations between hormones and emotional eating. Full article available at: http://www.sciencedirect.com/science/journal/14710153
Read
