SOD2 and Parkinson disease: Dopamine is an unstable molecule that causes the generation of ROS and dopamine quinones, in this region of the brain, causing OS, through auto-oxidation.41 This OS and mitochondrial dysfunction are central elements in the NDG in Parkinson’s disease.67 Aging reduces the ability to maintain antioxidant mechanisms against OS, through reduced activity and expression of antioxidant genes, such as SOD2, catalase and glutathione peroxidase.9,35