Alterations in AQ4 expression have been reported in age-related tau astrogliopathy (ARTAG) [37, 71], in astrocytes surrounding β-amyloid plaques, and in perivascular astrocytes in AD [60]; reactive astrocytes in bovine spongiform encephalopathy and related models, in which reactive astrocytes do not contain hyper-phosphorylated tau and PrPSC, respectively, also express high levels of AQ4 [18]. This evidence concerns the gene MAPT and Alzheimer disease.