Deriving behavioural phenotypes in an international, multi-centre study of eating disorders.

BACKGROUND An international, multi-site study funded by the Price Foundation has collected 237 affected relative pairs to identify potential genetic factors that may contribute to the pathogenesis of anorexia nervosa (AN). The current report utilized this sample to derive phenotypes from the personality and behavioural traits assessed in a large number of individuals with eating disorders. METHODS Multivariate analytical techniques were used to characterize the relationships among personality (e.g. trait anxiety, perfectionism, harm avoidance, novelty seeking) and behavioural traits (obsessions and compulsions) in individuals with eating disorders (primarily AN; N = 348) and assess the effectiveness of these traits in classifying subjects into diagnostic subtypes. RESULTS Factor analysis revealed that the most influential factor was one of trait anxiety, harm avoidance, perfectionism, obsessive-compulsive behaviours, and diminished self-directedness, although the precise nature of this factor differed slightly across sites. Discriminant analysis was used to evaluate the utility of these personality/behavioural factors in predicting subdiagnosis. Overall, the misclassification rate was 34%; however, there was an 80% rate of accurate classification of those individuals with a diagnosis of restricting-type AN. CONCLUSIONS Trait anxiety, harm avoidance, perfectionism, obsessive-compulsive behaviours and diminished self-directedness may best be conceptualized as parts of the same underlying construct among individuals with eating disorders, particularly AN. These personality and behavioural traits were also found to be of some utility in classifying eating disordered individuals into diagnostic subgroups, particularly those with restricting-type AN. We expect these phenotypic findings to benefit our ongoing search for genetic loci underlying the liability to eating disorders.