OBSESSIVE-COMPULSIVE PERSONALITY DISORDER: EVIDENCE for TWO DIMENSIONS

Background To determine possible dimensions that underlie obsessive-compulsive personality disorder (OCPD) and to investigate their clinical correlates, familiality, and genetic linkage. Methods Participants were selected from 844 adults assessed with the Structured Instrument for the Diagnosis of DSM-IV Personality Disorders (SIDP) in the OCD Collaborative Genetics Study (OCGS) that targeted families with obsessive-compulsive disorder (OCD) affected sibling pairs. We conducted an exploratory factor analysis, which included the eight SIDP-derived DSM-IV OCPD traits and the indecision trait from the DSM-III, assessed clinical correlates, and estimated sib-sib correlations to evaluate familiality of the factors. Using MERLIN and MINX, we performed genome-wide quantitative trait locus (QTL) linkage analysis to test for allele sharing among individuals. Results Two factors were identified: Factor 1: order/control (perfectionism, excessive devotion to work, overconscientiousness, reluctance to delegate, and rigidity); and Factor 2: hoarding/indecision (inability to discard and indecisiveness). Factor 1 score was associated with poor insight, whereas Factor 2 score was associated with task incompletion. A significant sib-sib correlation was found for Factor 2 (rICC =.354, P <.0001) but not Factor 1 (rICC =.129, P =.084). The linkage findings were different for the two factors. When Factor 2 was analyzed as a quantitative trait, a strong signal was detected on chromosome 10 at marker d10s1221: KAC LOD = 2.83, P =.0002; and marker d10s1225: KAC LOD = 1.35, P =.006. Conclusions The results indicate two factors of OCPD, order/control and hoarding/indecision. The hoarding/indecision factor is familial and shows modest linkage to a region on chromosome 10.