Personality differences in schizophrenia are related to performance on neuropsychological tasks

Altered cognition and personality appear to emerge in tandem and adversely affect outcome in schizophrenia, yet little research has been done to determine whether these are related or independent domains. In this study, the relationship between the Big Five personality traits--neuroticism, extraversion, openness, agreeableness, conscientiousness--and cognitive and motor performance in outpatients with chronic, clinically stable schizophrenia (N = 30) and age-matched healthy comparison subjects (N = 45) was examined. Subjects completed tests of attention, executive and motor functions, and the NEO-Five Factor Personality Inventory. Patients scored significantly higher on neuroticism and lower on extraversion and agreeableness, but after variance due to neuropsychological performance was statistically removed from NEO scale scores, personality dimensions and profiles no longer differed between groups. Neuropsychological performance and demographic variables, but not diagnosis, uniquely accounted for statistically significant amounts of personality variance, and neuropsychological task performance was correlated with personality dimensions in both patients and comparison subjects. These cross-sectional data provide preliminary evidence that personality dysfunction in schizophrenia may be mediated by disease-related changes in cognitive operations, or the neural processes underlying them. Longitudinal studies utilizing more comprehensive measures of neurocognitive performance are needed to define further the relationship between neuropsychological function and personality in schizophrenia.