Comorbidity in a clinical sample of substance abusers.

The sample consisted of 125 male inpatients admitted to one of two substance abuse treatment centers in Iowa. They were diagnosed by means of the Diagnostic Interview Schedule Screening Interview-Quick-DIS version, the Structural Interview for DSM-III-R Personality Disorder (PD), revised, and the Substance Abuse Reporting System. The most frequently diagnosed comorbid Axis I conditions were anxiety and mood disorders, while the most frequently observed Axis II disorders were in Cluster B, borderline PD, and antisocial PD followed by Cluster C, avoidant PD, passive-aggressive PD and obsessive-compulsive PD; and then Cluster A; schizoid PD. Subjects diagnosed with Borderline PD showed the highest rate of comorbid psychopathology, including Axis I disorders of generalized anxiety disorder, major depression, cocaine dependence, and inhalant dependence. The most likely comorbid diagnosis for antisocial PD subjects was bipolar disorder. The schizoid PD and the NoPD groups were less likely to meet criteria for other Axis I disorders. A high rate of comorbid Axis II pathology was also found. Polysubstance dependent subjects were more likely to be diagnosed with anxiety disorder or bipolar disorder than were those who were not polysubstance dependent or were dependent only on alcohol. Polysubstance dependent men were at highest risk for Axis II disorders: 56% of them met criteria for a Cluster B PD, with borderline PD and histrionic PD most frequent.