AQP4 and Alzheimer disease: Decreased GFAP+ immunoreactive surface and astrocyte process [169], decreased colocalization of CD31 and GFAP [108], as well as decreased AQP4 level [41] are observed in 3 × Tg‐AD mice (6–7 months), APP/PS1 (6–9 months) mice, and TgCRND8 (14 months) mice, which indicate structural detachment between astrocyte endfeet and endothelial cells.