MAPT and Alzheimer disease: A recent study reported that hippocampal astrocytes in the dentate gyrus of AD patients exhibit hyperphosphorylated tau, and this abnormal tau impairs Ca2+ oscillation and mitochondria motility, distribution, and function in astrocytes, contributing also to reduce: (i) adult neurogenesis; (ii) parvalbumin-expressing neurons; (iii) inhibitory synapses; and (iv) hilar gamma oscillations, which were accompanied by a weakened spatial memory performance (Richetin et al., 2020).