SOD2 and Alzheimer disease: Balendra and Singh (2021) showed that Mn-SOD decreases Bace1 expression while inhabiting the deposition of Aβ plaque and tau protein. SOD supplementation prevented cognitive decline by reducing lipid peroxidation and maintaining hippocampal neurogenesis in mice models. In addition, studies have reported the dysfunction of Mn transporters in AD mice and patients (Tian et al., 2018). We infer that the decreased plasma Mn in the CI group may have been the result of dysfunctional Mn transporters, which can maintain Mn homeostasis (Kumar et al., 2019).