Circulatory antioxidant and oxidative stress markers are in correlation with demographics but not cognitive functions in multiple sclerosis patients

•Oxidative stress (OXS) is a major basis of the pathogenesis of MS.•Neither endogenous antioxidant factors including catalase activity (CAT), glutathione peroxidase 1 and 2 (GPX1, GPX2), reduced glutathione (GSH), total antioxidant capacity (TAC), and superoxide dismutase (SOD) nor malondialdehyde (MDA), as an OXS biomarker, are associated with the cognitive function or physical disability in MS patients.•The level of CAT and TAC in male MS patients is higher than in females. Type of MS is associated with levels of GPX1, 2, and SOD. Multiple sclerosis (MS) is the most common non-traumatic cause of disability in younger adults. MS can be presented with a wide range of symptoms such as cognitive impairment (CI). Oxidative stress (OXS) is a major basis of the pathogenesis of MS. There is a positive correlation between OXS factors and the progression of the disease in MS patients. There are limited studies regarding the role of OXS in MS-related CI. In this study, as an exploratory analysis, we assess the role of endogenous antioxidants and OXS factors in cognitive function, the severity of disability due to MS, and demographic findings in a sample of MS patients. Adult (>18 years old) patients with a definite diagnosis of MS based on 2017 revised MacDonald criteria were included in this study. The neurophysiological assessment was conducted, using the validated Persian version of minimal assessment of cognitive function in multiple sclerosis (MACFIMS) battery, which is composed of seven different tests. Based on the structure of the battery, CI was defined as a failure in at least two different components of the MACFIMS battery. The patients were separated into two groups of CI and non-CI. Examined antioxidant factors included catalase Activity (CAT), Glutathione Peroxidase 1 (GPX1), Glutathione Peroxidase 2 (GPX2), Reduced Glutathione (GSH), Superoxide Dismutase (SOD), and serum total antioxidant capacity (TAC). Malondialdehyde (MDA) was also measured as an OXS marker. 71 patients were involved in this study. The type of MS was relapsing-remitting MS (RRMS) in 80.28% of the participants. Disease duration (P