Personality characterizations of outpatients with schizophrenia, schizophrenia with substance abuse, and primary substance abuse

The study extended previous research on the relationship between personality traits and Axis I disorders. It examined personality differences between individuals diagnosed with schizophrenia and substance abuse and also included individuals dually diagnosed with both schizophrenia and substance abuse. Comparisons were made with respect to characteristics of both normal personality, as measured by the NEO Five-Factor Inventory (NEO-FFI), and disordered personality, as measured by the Millon Multiaxial Personality Inventory. On the NEO-FFI, all groups differed significantly from the NEO-FFI normative sample on at least three personality domains. As predicted, the dual diagnosis group showed the most personality deviance and pathology. The schizophrenia group was primarily distinguished by higher levels of agreeableness, whereas the substance abuse group was more extroverted and showed a prominence of Cluster B personality patterns. An unexpected finding was an interaction between diagnostic group and age, such that older relative to younger individuals in the single diagnosis groups showed greater personality adaptivity and moderation, whereas older individuals in the dual diagnosis group showed less.