The brain is one of the most metabolically active organs in the body, and continuous removal of excess fluid and waste products is critical for normal brain function. In contrast to other body organs, the brain lack lymphatic vessels for detoxification. In place of lymphatic vessels, the brain uses a so-called glymphatic pathway which comprise the peri-vascular space and acuaporin-4 water channels on astroglial endfeet. As such the glymphatic pathway can be perceived as a hitherto overlooked compartment of the extracellular space of the central nervous system which is involved in clearance of amyloid-beta and other neurotoxic waste substances that build up in the brain.