Cognitive deficits in individuals with comorbid personality disorder and schizophrenia: A scoping review.

Objective: It is estimated that approximately 40 % of individuals diagnosed with schizophrenia also meet the diagnostic criteria for a personality disorder. This comorbidity is associated with an unfavorable prognosis for the illness. Given that cognition is currently the best predictor of recovery, this study aims to characterize the cognitive profiles of individuals with comorbid personality disorders and schizophrenia by reviewing literature from the past 24 years. We sought to determine whether the cognitive deficits differed from that of individuals with only a schizophrenia diagnosis, and to further characterize these differences. Method: Articles were gathered from PubMed, Google Scholar, Web of Science, PsychInfo, PsychNet, MedLine, and EMBASE. They were selected based on the following inclusion criteria: (a) use of neuropsychological or social cognition measures, (b) explicit mental disorder diagnosis established using validated diagnostic tools, (c) participants with a comorbid personality disorder and schizophrenia diagnosis, and (d) results of neuropsychological measures specific to participants with this type of comorbidity. Results: A total of 10 articles were included. Of these, six clinically established a personality disorder diagnosis, while five measured traits associated with various personality disorders. Due to the heterogeneity of methodologies across the studies, no statistical conclusions could be drawn. Discussion/conclusion: Our review did highlight a greater presence of studies on antisocial personality, with few on other personality disorders or traits. Given the high comorbidity of personality disorders in schizophrenia, and the important impact of cognition on functioning, including social cognition, more studies are warranted. Recommendations for both clinicians and researchers are proposed.