Study investigating executive function in schizophrenia patients and their unaffected siblings

Abstract

Background: Schizophrenia (SCZ) is a serious genetic mental illness. Most research indicates that executive impairment has a certain genetic predisposition. The shared neuropathological characteristics of patients with schizophrenia and their siblings might reveal intermediate phenotypes in behavior that could be used to further characterize the illness. Methods: Our study involved 32 schizophrenia patients, 32 unaffected siblings,and 33 healthy controls. The three groups underwent a computerized version of the Wisconsin Card Sorting Test (WCST) and a battery of cognitive neuropsychological assessments. These tests evaluated executive function and several cognitive domains. Results: In this study, the WCST results demonstrate that the total correct (TC), total error (TE), perseverative response (PR) and perseverative error (PE) scores in the SZ group were significantly lower than those in the HC group (TC (p=0.011), TE (p<0.001), PR (p=0.007) and PE (p=0.002)), and compared to the unaffected siblings, we found significant differences in TE (p=0.003). Moreover, significant differences were observed between the unaffected siblings and healthy controls as follows: TC (p=0.034), TE (p=0.008), PR (p=0.016) and PE (p=0.013). Conclusion: The schizophrenia patients and their siblings performed worse in the WCST test than the healthy controls. This result supports the claim that the development of functional impairment is not unique to schizophrenia patients and that unaffected siblings may have a certain level of abnormal brain function.Neurological abnormalities lead to abnormal functioning in siblings and patients,suggesting that genetics plays a considerable role in such results.