MAPT and Alzheimer disease: In transgenic mouse models such as APPswe/PS1ΔE9, 5×FAD, and 3×Tg-AD, significant reductions in neural progenitor cell proliferation and neurogenesis have been observed as early as 2–3 months of age—prior to the detectable deposition of Aβ plaques or Tau hyperphosphorylation [8,9,10,11].