MAPT and Alzheimer disease: Currently, however, these staging schemes have primarily focused on neuronal (e.g., α-synuclein in Lewy body disorders or tau for neurofibrillary tangle (NFT) formation in Alzheimer’s disease, AD) or extracellular protein deposits (e.g., Aβ in AD), without consideration of glial involvement (Liddelow and Sofroniew, 2019).