These natural or synthetic antioxidants include glutathione peroxidase, Catalase (CAT), glutathione reductase, Superoxide Dismutase (SOD), Nicotinamide Adenine Dinucleotide Phosphate (NADPH), vitamin C, mannitol, bilirubin, and Glutathione (GSH), β-carotene, which play a major role in ROS reduction in AD [9]. The gene discussed is CAT; the disease is Alzheimer disease.