Synopsis

Interstitial fluid of the brain drains along the walls of capillaries and arteries as intramural periarterial drainage (IPAD). This process fails with ageing and possession of APOE4 genotype, resulting in cerebral amyloid angiopathy (CAA). There is convective influx/glymphatic entry of cerebrospinal fluid (CSF) along the pial glial basement membranes into the brain parenchyma.