Deriving behavioural phenotypes in an international, multi-centre study ofeating disorders

Background. An international, multi-site study funded by the Price Foundati on has collected 237 affected relative pairs to identify potential genetic factors that may contribute to the pathogenesis of anorexia nervosa (AN), T he current report utilized this sample to derive phenotypes from the person ality and behavioural traits assessed in a large number of individuals with eating disorders. Methods. Multivariate analytical techniques were used to characterize the r elationships among personality (e,g, trait anxiety, perfectionism, harm avo idance, novelty seeking) and behavioural traits (obsessions and compulsions ) in individuals with eating disorders (primarily AN; N = 348) and assess t he effectiveness of these traits in classifying subjects into diagnostic su btypes, Results. Factor analysis revealed that the most influential factor was one of trait anxiety, harm avoidance, perfectionism, obsessive-compulsive behav iours, and diminished self-directedness, although the precise nature of thi s 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 diag nosis of restricting-type AN. Conclusions. Trait anxiety, harm avoidance, perfectionism, obsessive-compul sive behaviours and diminished self-directedness may best be conceptualized as parts of the same underlying construct among individuals with eating di sorders, particularly AN. These personality and behavioural traits were als o 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.