Under basal conditions, tau expression is 5 and 10 times lower in astrocytes than in neurons in humans and mice, respectively.13,16 Under physiological conditions, several astrocytic mechanisms contribute to the regulation of neuronal function, synaptic integrity and plasticity.17 Therefore, alterations in astrocytic function may contribute to synaptic loss in Alzheimer’s disease;18 however, the extent of this contribution is currently unclear. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.