Contrary to the marked microglial activation reported in APP-based mice models and in human neocortical AD regions, we demonstrated a prominent degenerative process of the microglia in the dentate gyrus (DG) and CA3 of Braak V–VI samples, probably associated with the accumulation of soluble phospho-tau, as determined by in vitro assays. This evidence concerns the gene MAPT and Alzheimer disease.