OBJECTIVE: This study compared three-dimensional representations of DSM-IV personality disorders and standard categories with respect to their associations with psychosocial functioning.

METHOD: Six hundred sixty-eight patients with semistructured interview diagnoses of schizotypal, borderline, avoidant, or obsessive-compulsive personality disorders or with major depressive disorder and no personality disorder completed questionnaires assessing three-factor and five-factor dimensional models of personality. Personality disorder categories, dimensional representations of the categories based on criteria counts, and three- and five-factor personality dimensions were compared on their relationships to impairment in seven domains of functioning, as measured by the Longitudinal Interval Follow-up Evaluation-Baseline Version.

RESULTS: Both the categorical and dimensional representations of DSM-IV personality disorders had stronger relationships to impairment in functioning in the domains of employment, social relationships with parents and friends, and global social adjustment and to DSM-IV axis V ratings than the three- and five-factor models. DSM-IV dimensions predicted functional impairment best of the four approaches. Although five-factor personality traits captured variance in functional impairment not predicted by DSM-IV personality disorder dimensions, the DSM-IV dimensions accounted for significantly more variance than the measures of personality.

CONCLUSIONS: Scores on dimensions of general personality functioning do not appear to be as strongly associated with functional impairment as the psychopathology of DSM personality disorder. A compromise in the ongoing debate over categories versus dimensions of personality disorder might be the dimensional rating of the criteria that comprise traditional categories.