Even though initial works have shown that some antioxidant enzymes present a greater activity in cells from AD patients (Zemlan et al., 1989), it has recently been shown that many antioxidant enzymes, such as SOD2, catalase and glutathione peroxidase, present lower activities in AD (Marcus et al., 1998; Omar et al., 1999; Wang et al., 2014). This evidence concerns the gene CAT and Alzheimer disease.