Cognitive Functioning, Glucose And Lip Metabolism In The First-degree Relatives Of Patients With Schizophrenia

Objective: To study cognitive functioning, glucose and lip metabolism in the first-degree relatives of patients with schizophrenia and identify if cognitive impairments, glucose and lip indicators are endophenotypes of schizophrenia.Methods: 110 first-degree relatives of patients with schizophrenia and 50 matched controls were assessed with Continuous Performance Test (CPT), Wisconsin Card Sorting Test(WCST), Similarities, Block Design , Digit Span subtests from Wechsler Adult Intelligence Scale-Revised(WAIS-R), Logical Memory and Visual Reproduction subtests from Wechsler Memory Scale-Revised, Stroop Word Color Test and Verbal Fluency Test. Oral glucose tolerance test were performanced, and fasting, 15-minute, 30-minute, 60-minute, 120-minute blood glucose, Serum triglycerides, high density lipoprotein, Low density lipoprotein, Serum total cholesterol were measured in all the subjects. The cognitive performance of all these tests, glucose and lip levels in the relatives of patients with schizophrenia and matched controls were compared.Results: Compared with control group, first-degree relatives of patients with schizophrenia showed significantly impaired in performance of color read, immediate and delayed logical memory, delayed visual reproduction, visual reproduction saving score, verbal fluency total number and correct number, omission number and mean reaction time 1(mean target-reaction time), mean reaction time 2(mean non-target-reaction time) of both visual and auditory CPT. Siblings and offspring didn't performed more poorly than parents of patients with schizophrenia in all tests except comission error of auditory CPT.First-degree relatives of patients with schizophrenia showed lower fasting blood glucose level compared with matched controls, but both are in the normal range. However, there is no significant difference between two groups in all glucose levels of oral glucose tolerance test, areas under the glucose curves, lip level, IFG, IGT, DM and the prevalence of abnormal glucose metabolism. Both relatives with and without schizotaxia showed significantly lower fasting blood glucose level, and the glucose level of relatives with schizotaxia at 15 minute after taking glucose were lower than those of relatives without schizotaxia and control group, but all of these are in the normal range.Conclusions: First-degree relatives of patients with schizophrenia are impaired in attention, verbal memory, visual spatial memory, suggesting these indicators may be endophenotypic markers of schizophrenia . There were no apparent impairments in glucose and lip level of first-degree relatives of patients with schizophrenia, indicating that glucose and lip indicators are not endophenotypes of schizophrenia.