PHENOTYPIC AND GENETIC-STRUCTURE OF TRAITS DELINEATING PERSONALITY-DISORDER

Background: The evidence suggests that personality traits are hierarch ically organized with more specific or lower-order traits combining to form more generalized higher-order traits. Agreement exists across st udies regarding the lower-order traits that delineate personality diso rder but not the higher-order traits. This study seeks to identify the higher-order structure of personality disorder by examining the pheno typic and genetic structures underlying lower-order traits. Methods: E ighteen lower-order traits were assessed using the Dimensional Assessm ent of Personality Disorder-Basic Questionnaire in samples of 656 pers onality disordered patients, 939 general population subjects, and a vo lunteer sample of 686 twin pairs. Results: Principal components analys is yielded 4 components, labeled Emotional Dysregulation, Dissocial be havior, Inhibitedness, and Compulsivity, that were similar across the 3 samples. Multivariate genetic analyses also yielded 4 genetic and en vironmental factors that were remarkably similar to the phenotypic fac tors. Analysis of the residual heritability of the lower-order traits when the effects of the higher-order factors were removed revealed a s ubstantial residual heritable component for 12 of the 18 traits. Concl usions: The results support the following conclusions. First, the stab le structure of traits across clinical and nonclinical samples is cons istent with dimensional representations of personality disorders. Seco nd, the higher-order traits of personality disorder strongly resemble dimensions of normal personality. This implies that a dimensional clas sification should be compatible with normative personality. Third, the residual heritability of the lower-order traits suggests that the per sonality phenotypes are based on a large number of specific genetic co mponents.