Sex influences on shared risk factors for bulimia nervosa and other psychiatric disorders.

BACKGROUND The examination of opposite-sex and same-sex dizygotic twins allows us to explore the sex-specific comorbidity of psychiatric disorders. To date, this question has not been explored in eating disorders. OBJECTIVE To determine whether sex influences shared risk factors between bulimia nervosa (BN) and other forms of psychopathology. DESIGN The study examines associations between BN and other forms of psychopathology in twin pairs using interview and survey reports. SETTING Twins from the Virginia population-based twin registry. PARTICIPANTS Male-female dizygotic twins (N = 1192 pairs), mean (SD) age 36.6 (8.9) years, and female-female dizygotic twins (N = 467 pairs), mean (SD) age 36.0 (7.6) years. MAIN OUTCOME MEASURES Lifetime psychiatric disorders as diagnosed by a structured psychiatric interview, including major depression, anxiety disorders, and substance abuse and dependence. Also, continuous measures of body mass index and personality, including neuroticism and novelty seeking. RESULTS Significant within-person associations existed for women between BN and higher body mass index, neuroticism, novelty seeking, and all lifetime psychopathology. Results from this study suggest the presence of either familial or nonfamilial shared risk factors between BN and generalized anxiety disorder, neuroticism, psychoactive substance use, novelty seeking, major depression, and panic disorder. The shared risk factors between BN and generalized anxiety disorder and BN and novelty seeking were only present in men. CONCLUSION Evidence supports the existence of a sex-specific manifestation of familial liability with respect to BN and generalized anxiety disorder and BN and novelty seeking.