Furthermore, AQP4, highly polarized at the end-feet of astrocytes, facilitates the transport of CSF from perivascular spaces into the ISF space and active flushing of ISF[24]; this supports the crucial role of astrocytes in the glymphatic system.[39] Polarized AQP4 on perivascular astrocytic end feet is a strong regulator of normal glymphatic function.[40] Additional evidence of the aberrant location of AQP4 on astrocyte end feet and damage was related to cognitive dysfunction, which can be described in animal models of CADASIL. The gene discussed is AQP4; the disease is CADASIL.