GFAP and Alzheimer disease: Postmortem analyses of astrocytosis in human AD brain tissues have reported activated GFAP-positive astrocytes next to fibrillar Aβ plaques [15, 16], and one study found that GFAP was significantly age-related, as both the protein and mRNA levels of GFAP were increased in the hippocampus of aged senescence-accelerated-prone mice (SAMP8) and senescence-accelerated-resistant mice (SAMR1) [48].