a1 Institute of Psychiatry and Maudsley Hospital, London; University of Wales College of Medicine, Cardiff
The Eating Attitudes Test (EAT) and the Eating Disorder Inventory (EDI) were administered to a female volunteer twin population aged 18 to 45 years. Both members of 147 monozygotic (MZ) and 99 dizygotic (DZ) twin pairs completed the questionnaires. Thirty-five subjects scored over the cut-off point of the EAT-26. Interviews of these high-scoring twins and their co-twins identified three subjects with a past history of anorexia nervosa, and three others with a history of a partial syndrome. A heritability value of 41% was obtained for the overall EAT scores, while factor analysis produced a ‘dieting’ factor with a heritability of 42%. The ‘body dissatisfaction’ and ‘drive for thinness’ subscales of the EDI had heritability values of 52 and 44% respectively. The genetic contribution to the variance in body mass index in the twin sample was estimated at 64%. For all the above phenotypes, an environmental model of transmission with heritability constrained to be zero, could be rejected. Conversely, we were unable to reject a purely additive genetic model with shared environmental variance constrained at zero, suggesting that family environment has little or no effect on the transmission of many of these traits.
c1 Address for correspondence: Dr Joan Rutherford, The Ridgewood Centre, Old Bisley Road, Frimley, Camberley, Surrey GU16 5QE.