Personality disorder and multiple substance dependence

DSM-III-R personality measures of individuals meeting criteria for multiple substance dependence were compared to those dependent on a single substance. Ninety-eight subjects in a substance abuse treatment program received DSM-III-R Axis I diagnoses by structured interview. Fifty-seven met criteria for multiple substance dependence; 41 were dependent on a single substance. Those dependent on multiple substances were more likely to have additional Axis I diagnoses such as major depression. To control for the effect of these disorders on personality scores, subjects with current Axis I diagnoses in addition to substance dependence (n = 29) were excluded from the personality analysis. Subjects completed the Personality Diagnostic Questionnaire Revised (PDQ-R), which yielded DSM-III-R Axis II personality disorder scores. Multiply dependent subjects scored significantly higher than subjects dependent on a single substance on the borderline and antisocial scales. The number of substances subjects had been dependent on correlated significantly with these scale scores as well. The results are consistent with the idea that multiple substance dependence is associated with greater personality pathology.