AQP4 and Alzheimer disease: In AD, AQP4 polarity loss significantly weakens glymphatic clearance, exacerbating Aβ accumulation; Aerobic exercise can restore AQP4 polarization, enhance CSF–ISF exchange, and markedly reduce soluble Aβ levels in AD rodent brains, thereby delaying cognitive decline (Xie et al., 2013; Liu et al., 2022).