Despite the use of binge eating and compensatory behavior in distinguishing diagnostic categories and subtypes of eating disorders, little research has examined the etiologic validity of distinguishing among disorders/subtypes based on these phenotypes. The current project used cross-sectional and longitudinal data to examine etiologic overlap between binge eating and compensatory behavior and explore impulsivity as a differentiating factor in the relationship between these variables. Participants included 1,434 female twins from two twin registries. Binge eating and compensatory behavior were assessed with the Minnesota Eating Behavior Survey. Impulsivity was assessed with the control subscale of the Multidimensional Personality Questionnaire. Pearson correlations were used to examine phenotypic associations and trivariate Cholesky decompositions were used to explore etiologic associations between impulsivity, binge eating and compensatory behaviors (cross-sectionally and across-time). Cross-sectional and longitudinal findings indicated a small-to-moderate degree of overlap between binge eating and compensatory behavior. In addition, although overlap with impulsivity was generally small for both phenotypes, greater phenotypic and etiologic associations were found between impulsivity and compensatory behavior. Genetic relatedness appears to account for more overlap between the three variables than nonshared environmental influences, with compensatory behavior sharing greater overlap with impulsivity than binge eating. However, residual estimates are substantial, indicating most of the etiology of binge eating and compensatory behavior is unaccounted for by impulsivity. Substantial etiologic uniqueness in binge eating and compensatory behavior suggests merit in the addition of diagnostic categories that focus on one behavior in the absence of the other (e.g., purging disorder). Findings also indicate impulsivity may be a differentiating factor between these disordered eating phenotypes.
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