An investigation of temperament endophenotype candidates for early emergence of the core cognitive component of eating disorders.

BACKGROUND This study was designed to investigate potential temperament endophenotypes for clinically significant importance of shape and weight. METHOD Seven temperament risk factors for eating disorders and the Eating Disorder Examination were assessed in 699 female twins aged 12-15 years. Each variable was evaluated against the following endophenotype criteria: associated with illness in the general population; found in non-affected family members at a higher rate than in the general population; and, heritable. RESULTS All seven variables were significantly associated with clinically significant importance of shape and weight, while thin-ideal internalization, ineffectiveness, body dissatisfaction and sensitivity to punishment were found at significantly elevated levels in non-affected twins, when controlling for sister's temperament score. These four variables had genetic correlations with importance of shape and weight, ranging from 0.48 to 0.95. CONCLUSIONS Future research should evaluate the stability of the identified endophenotypes and their utility for predicting significant growth in importance of shape and weight, and also whether different endophenotypes emerge when the importance of weight and shape reaches its peak in adolescents, around 15 to 16 years of age.