Although cytoskeletal hypertrophy and upregulation of GFAP were found in the late stages of AD mouse models and in human postmortem tissue,80 at the onset stages of AD in the 3xTg‐AD mice and in the PDAPP‐J20 mice, there is a progressive astrocytic atrophy with decreased GFAP staining in the cortex and hippocampus.81, 82 The switch from atrophic phenotype at the early stage to later hypertrophic phenotype may be associated with the formation of amyloid plaques, since only the astrocytes directly associated with amyloid plaques became hypertrophic. This evidence concerns the gene GFAP and Alzheimer disease.