Effects of oxidative stress on cognitive impairment in first episode schizophrenia

Abstract

Objective: To observe the relationship between serum oxidative stress as well as brain-derived neurotrophic factor (BDNF) and cognitive function in first-episode drug-free schizophrenics, and to explore the possible effect of oxidative stress in cognitive impairment of first-episode schizophrenia. Methods: A total of 125 first-episode drug-free schizophrenics (schizophrenia group) from the First Affiliated Hospital of Zhengzhou University and 80 healthy individuals (control group) were enrolled. The serum concentration of oxidized glutathione (GSSG) was measured by the Microenzyme method the serum concentration of nitric oxide (NO) was measured by one-step method, the BDNF level was measured by enzyme linked immunosorbent assay and Matrics Consensus Cognitive Battery(MCCB) was used to evaluate the cognitive function. Results: (1)The serum level of BDNF in schizophrenia group (2 763±1 728 pg/ml) was significantly lower than that in control group (4 165±1 299 pg/ml)(P<0.001). And the serum levels of GSSG and NO in schizophrenia group ((36±9), (81±65) μmol/L) were significantly higher than that in control group ((27±11), (24±16) μmol/L) (P<0.001). In comparison with the control group scores were significantly lower in the seven domains of cognitive function in the schizophrenia group (all P<0.001). (2)After controlling the confounding factors like age, gender, cultural differences and course of disease by partial correlation analysis, the correlation analysis showed that: serum level of BDNF in schizophrenia group had positive correlation with Information processing rate T points, attentional facilitating T points, working memory T points and Reasoning and problem solving T points (r=0.417, 0.206, 0.247, 0.318, all P<0.05). In schizophrenia group the serum level of GSSG had a negative correlation with information processing rate T points and reasoning and problem solving T points (r=-0.321, -0.231, all P<0.05). The serum level of NO was negatively related to Information processing rate T points working memory T points Verbal learning T points(r=-0.201, -0.193, -0.237, all P<0.05). Conclusions: Oxidative stress may be involved in the cognitive impairment of schizophrenia Oxidation products are risk factors for cognitive impairment of schizophrenia and BDNF is a protective factor of cognitive function.