APOE and Alzheimer disease: Together, these data suggest that neuronal ApoE, particularly the subtype ApoE4, play a pathogenic role in AD-associated selective neuronal degeneration and loss, age and genetic subtype-related variation in ApoE expression in astrocytes is absent (Bilheimer, 1988; Price et al., 1998; Bilousova et al., 2019; Marais, 2019).