CAT and Parkinson disease: In case of oxidative stress markers, levels of malondialdehyde (MDA), 8-Oxo-2'-deoxyguanosine (8-oxo-dG), and lipid hydro-peroxide (LPO) were found to be high in patients with PD as compared to controls with P < 0.05, whereas lower levels of antioxidant activity of superoxide dismutase (SOD), glucose 6 phosphate dehydrogenase (G6PD), catalase (CAT), and glutathione peroxidase (GPx) were noticed in the PD group as compared to controls (P < 0.05 for all).