Neurocognitive deficits are recognized as core features of schizophrenia. The aim of this study was to compare the cognitive performance of antipsychotic, drug-naive patients with first-episode schizophrenia (FES patients) to their healthy siblings and to healthy controls from the Han Chinese population for exploring potential endophenotypes for the early detection of schizophrenia. A battery of cognitive assessment tools was used to measure seven cognitive domains in matched groups consisting of 56 subjects each. Cognitive tests included the grooved pegboard test (GPT), the category fluency test (CFT), the trail making test A (TMT-A), the Wechsler memory scale-III spatial span test (WMS-III SST), the Hopkins verbal learning test-revised (HVLT-R), the brief visuospatial memory test-revised (BVMT-R), the paced auditory serial addition test (PASAT), and the Wisconsin card sorting test-64 cards version (WCST-64). The performances of FEP patients were inferior to normal controls on all neuropsychological tests, while siblings were lower than healthy controls in many of the same tasks. Patients' performances were lower than siblings' on all tests except for the CFT, the WMS-III SST backward test, and four subtests of the WCST-64. Our data suggest that FEP patients exhibited pronounced impairment of fine motor skills, speed of processing, attention, verbal memory, visual memory, and executive function, while siblings exhibited deficits intermediate between those of schizophrenic patients and the control group. Semantic fluency function and executive function may be potential endophenotypes for the early diagnosis of schizophrenia.
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