According to a new study, rejuvenating immune cells that live in tissues surrounding the brain improves fluid flow and waste clearance from the brain and may help treat or even prevent neurodegenerative diseases like Alzheimer's and Parkinson's. Alzheimer's, Parkinson's, and many other neurodegenerative diseases are characterized by protein clusters that cause damage in the brain. Scientists have worked tirelessly to find ways to treat such conditions by removing toxic clusters, but they have had limited success. Researchers at Washington University School of Medicine in St. Louis have discovered a novel way to improve waste clearance from the brain, potentially treating