Comorbid personality traits in schizophrenia: prevalence and clinical characteristics

Accumulating evidence suggests high rates of personality disorder (PD) in schizophrenia (Sz), and as such, the implications of PD in this context are beginning to be studied more thoroughly. We examined clinical, cognitive and experiential (i.e., reported childhood adversity) correlates of aberrant personality traits in schizophrenia and healthy controls (HC) as measured by the International Personality Disorder Examination Questionnaire (IPDEQ). Participants were 549 individuals with schizophrenia or schizoaffective disorder, and 572 healthy adults recruited to the Australian Schizophrenia Research Bank (ASRB). Schizophrenia participants were significantly more likely than healthy controls to screen positive for personality disorder across all ICD-10 subtypes, and there was substantial overlap between clusters, with ∼33% of Sz participants screening positive for all 3 personality disorder clusters. Among both Sz and HC groups, cluster B personality characteristics were significantly associated with increased suicidal behaviours, lower cognitive performance, and the experience of childhood adversity. In addition, Cluster C personality features were associated with higher overall ratings of affective blunting in schizophrenia, and Cluster A personality features were associated with childhood 'loss' in HC participants only. The cumulative effects of screening positive for more than one personality disorder in Sz was associated with higher likelihood of suicidal behaviour, earlier age of onset of Sz, and poorer cognitive functioning. The results suggest that abnormal co-occurrence of personality traits across DSM-IV clusters is evident in a significant proportion of individuals with schizophrenia, and that these personality features impact significantly on clinical and cognitive characteristics of Sz.