Alzheimer’s researchers are studying the brain’s plumbing

IN MOST BODILY organs waste matter is cleared out by the lymphatic system. Unnecessary proteins, superfluous fluids and so on are carried away by special vessels to lymph nodes, where they are filtered out and destroyed. The more active the organ, the more of these vessels there are. The exception is the brain, which has none. It was thus thought until recently that brain cells broke down nearby waste products .But a paper published in 2012 reported that the brain has a plumbing system of its own to flush out the junk. Researchers working in the laboratory of Maiken Nedergaard, at University of Rochester, in New York state, showed that cerebrospinal fluid—the liquid which suspends the brain and acts as a cushion between it and the skull—was actively washing through the organ by hitchhiking on the pulsing of arteries and veins that happens with every heartbeat. The fluid was collecting trash and carrying it out of the brain to lymph nodes for disposal. Now, ten years later, the discovery of this “glymphatic” system, so called because of the involvement of brain cells known as glia, has opened up new opportunities for the treatment of brain disorders.