MAPT and Alzheimer disease: The common denominator in the degenerative pathologies analyzed in this review is the activation of microglia and astrocytes resulting from the accumulation of molecular aggregates of various nature, such as β-amyloid plaques and tau protein-containing neurofibrillary tangles, GlcNAc polymers, observed in AD, αSyn aggregates in PD, and DLB and TDP-43 in ALS (Figure 2).