Personality traits and schizophrenia: evidence from a case-control study and meta-analysis

Personality is considered to be an important aspect of schizophrenia, primarily because it may influence patients' symptoms and social functioning. Specific personality traits are related to schizophrenia. The Temperament and Character Inventory (TCI) measures four traits of temperament - novelty seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (PS) - and three traits of character - self-directedness (SD), cooperativeness (CO) and self-transcendence (ST). We investigated associations between schizophrenia and personality traits using the TCI in a Japanese case-control sample (99 patients and 179 controls). Patients with schizophrenia scored higher on HA and ST and lower on NS, RD, SD and CO compared with controls in our case-control sample. We then performed a meta-analysis of samples from the published literature and our sample (384 patients and 656 controls). We found no evidence of heterogeneity among studies, except for NS in the overall population. Possible associations between personality traits (HA, RD, PS, SD, CO and ST) and schizophrenia were revealed. The effect sizes (Hedges' g) of the temperament traits were 0.98 for HA, -0.43 for RD and -0.23 for PS, and those of the character traits were -0.96 for SD, -0.47 for CO and 0.61 for ST. These findings suggest that patients with schizophrenia have a unique temperament and character profile compared with the general population.