Schematic depiction of the glymphatic pathway in the brain. In this brain-wide pathway, cerebrospinal fluid from the subarachnoid space rapidly enters the brain along paravascular channels surrounding penetrating arteries and exchanges with brain interstitial fluid (ISF). ISF and parenchymal solutes (e.g., Aβ) are cleared from the brain along paravenous routes. The green arrow has been added as a reminder that fluid secreted by the blood–brain barrier contributes to the fluid in the parenchyma. Reproduced with permission from Hladky and Barrand , their Figure 9a (the glymphatic proposal).