In the serum or urine of AD patients, oxidative stress biomarkers, such as MDA, lipid LOOHs, NO•, and 8-OHdG, have been detected [122,123,124,125]; in addition, antioxidants, such as SOD, CAT, GSH, GPX, vitamins A, C, and E, were lower in AD patients compared to controls [126,127]. Here, GSS is linked to Alzheimer disease.