Researchers at the University of Rochester Medical Center report the system acts like a series of pipes that piggyback on the brain's blood vessels, a kind of parallel plumbing system to drain away waste products, serving the same function in the brain as the lymph system does in the rest of the body.
"Waste clearance is of central importance to every organ, and there have been long-standing questions about how the brain gets rid of its waste," senior study author Maiken Nedergaard. "This work shows that the brain is cleansing itself in a more organized way and on a much larger scale than has been realized previously.
The researchers dubbed the new system -- in mice, whose brains are remarkably similar to the human brain -- "the glymphatic system," since it acts much like the lymphatic system but is managed by brain cells known as glial cells.
Scientists have known cerebrospinal fluid plays an important role cleansing brain tissue, carrying away waste products.
The newly discovered system circulates the fluid to every corner of the brain much more efficiently, researchers said.
"It's as if the brain has two garbage haulers -- a slow one that we've known about, and a fast one that we've just met," Nedergaard said.
"We're hopeful that these findings have implications for many conditions that involve the brain, such as traumatic brain injury, Alzheimer's disease, stroke, and Parkinson's disease," she said.