Total Tau and Phosphorylated Tau Protein Serum Levels in Patients with Schizophrenia Compared with Controls

Abstract

Schizophrenia is a chronic and debilitating psychiatric disease that has various causes and symptoms. Tau protein is one of the biomarkers whose role is known in neurocognitive diseases and neurodegeneration. Considering the presence of cognitive symptoms in schizophrenia patients, in this study, our aim was to measure the serum level of tau total and phosphorylated tau as a cause and identifying factor in schizophrenia patients. Materials and methods: 40 patients with schizophrenia were selected according to study criteria and according to DSM-V criteria and SCID standard questionnaire. 40 healthy individuals who were matched in terms of age and sex. After obtaining a written consent, blood was taken from them and serum levels of tau total protein and phosphorylated tau were measured by ELISA method. Also, PANSS test was conducted to evaluate positive and negative symptoms in the schizophrenia group and demographic questionnaire for both groups. The results were analyzed with SPSS 23 software with appropriate statistical methods. Findings: Unpaired t-test was used to compare two groups of patients and controls in terms of total tau protein and phosphorylated tau protein. In this test, the two groups had no significant difference in total tau protein (P=0.14) and phosphorylated tau protein (P=0.24). Also, there was no significant difference between total and phosphorylated tau protein between men and women in the patient group. There was a significant correlation between total tau protein and phosphorylated tau of patients (Pearson R=0.77, P value<0.05). There was a significant correlation between the age of patients and the serum level of total tau protein (Pearson R=0.6, P value<0.05) and also between the age of patients and phosphorylated tau (Pearson R=0.6, P value<0.05). There was no correlation between total and phosphorylated tau protein serum level with PANSS test results. There was a weak correlation between age (Pearson R=0.3, P value<0.05) and also a moderate correlation between the time of disease onset and negative symptoms of the PANSS test (Pearson R=0.7, P value<0.05).