In the 3xTg, which contain three mutations associated with a familial AD (APP Swedish, MAPT P301L, and PSEN1 M146V) mouse model, atrophic astrocytes appear in the entorhinal cortex (EC) as early as 30 days and are present until Aβ plaques begin to emerge at 12 months of age [160]. Here, PSEN1 is linked to Alzheimer disease.