Executive Functions in Patients with Familial versus Sporadic Schizophrenia and Their Parents

BACKGROUND: The aim of this study was to investigate the executive functions in patients with sporadic schizophrenia (SS) and familial schizophrenia (FS), and the executive functions in their parents. METHODS: The study included 30 patients with FS and their 37 parents with a positive family history of schizophrenia; 30 patients with SS and their 44 parents; 30 controls matched with the patients for gender, age and education, and 40 controls matched with the parents for gender, age and education (211 subjects in total). All the subjects were interviewed with the Structured Clinical Interview for DSM-IV-Axis I (SCID-I). The executive functions were assessed using the Verbal Fluency Test (VFT), the Trail Making Test (TMT), the Wisconsin Card Sorting Test (WCST) and the Stroop Test. RESULTS: Patients with FS and their parents, and patients with SS performed significantly worse than their controls on the VFT, TMT, WCST and the Stroop test. There were no statistically significant differences between parents of patients with SS and their controls on any of the tests except for the Stroop color score. FS parents performed significantly worse than SS parents on all tests. FS patients performed significantly worse than SS patients on the VFT, TMT, Stroop test. CONCLUSION: Previous studies that investigated the cognitive functions of relatives of patients with schizophrenia brought out inconsistent results. The present study investigated relatives with and without a family history of schizophrenia separately and found that executive functions were impaired only in parents with a positive family history of schizophrenia. These findings suggest that impairment in executive functions may represent a genetic endophenotype for schizophrenia.