Are personality disorders psychological manifestations of executive function deficits? Bivariate heritability evidence from a twin study.

This study tested whether personality disorders may be the psychological manifestations of executive function deficits by examining their bivariate heritability in a community sample of 314 twins (ages 5-17 years; M age = 9.7; 96 monozygotic pairs and 61 dizygotic pairs). The parents of the twins completed the Coolidge Personality and Neuropsychological Inventory (Coolidge, 1998; Coolidge et al., 2002). Heritability was estimated by structural equation modeling. Executive function deficits and personality disorders were significantly heritable (executive function deficits,.77; 11 out of 12 personality disorders, median =.69). The proportion of the observed correlation attributable to heritable factors or bivariate heritability between executive function deficits and the personality disorder scales ranged from.27 for schizoid to.64 for histrionic. These findings may provide some insight as to why individuals diagnosed with specific personality disorders frequently exhibit chronic difficulties with everyday decisions, selective attention and inhibition, judgments, choices, planning, and flexibility.