Study on changes of plasma levels of oxidative stress biomarkers and its relation with cognition function in patients with parkinson's disease

Abstract

To study the changes of plasma levels of oxidative stress biomarkers in patients with parkinson's disease (PD), and to explore its association with cognition function. Seventy-two PD patients from June 2013 to May 2012 were enrolled. All of them were outpatients or inpatients at the First Affiliated Hospital of Nanjing Medical University. And forty-five age- and gender- matched healthy subjects were used as controls. The information including gender, age, illness duration, years of education and Hoehn & Yahr (H-Y) stage were recorded. Cognition function of all the patients with PD and the controls were measured by using Montreal Cognitive Assessment (MoCA) scale. Plasma levels of catalase (CAT), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), total glutathione (T-GSH) and malondialdehyde (MDA) were measured by ELISA . Then we compared and analyzed the results. Plasma levels of CAT, T-SOD and T-GSH in PD group were significantly lower than the control group [(159 ± 9) kU/L vs (170 ± 5) kU/L, P< 0.01; (97 ± 24) kU/L vs (124 ± 25) kU/L, P<0.01; (17 ± 10) µmol/L vs (60 ± 51) µmol/L, P< 0.01]. Plasma levels of CAT, T-GSH, GSH-Px and MDA were no differences between early PD group (H-Y stage I-II) and middle-late PD group (H-Y stage III or higher) of patients (P>0.05). Plasma levels of T-GSH in PD group with mild cognitive impairment (MCI) were obviously lower than PD group without MCI [(14 ± 7) µmol/L vs (19 ± 11) µmol/L, P< 0.05]. In PD patients, MoCA scores were positively correlated with years of education (β=0.634, P= 0.000) and plasma levels of T-GSH (β= 0.204, P= 0.014), and were negatively correlated with H-Y stage (β=-0.194, P=0.020). The damage of plasma antioxidant mechanism may be involved in the pathogenesis of patients with PD. Decrease in plasma levels of T-GSH may be associated with MCI in PD patients . Plasma levels of T-GSH may be a potential early predictive index in PD patients with cognitive dysfunction.