APP and Alzheimer disease: Dysfunction of neurogenesis in the DG area has been associated with AD in different transgenic animal models expressing mutant presenilin-1, mutant APP and in the 3xTg-AD [60–66] The evidence indicates that adult neurogenesis in the SGZ begins with a population of astrocytes called radial astrocytes that express ApoE, which is required for increasing neurogenesis [67,68].