Your Brain’s Self-Contained Garbage Disposal

A new study performed by neuroscientists at the University of Rochester and Stony Brook University in New York and at the University of Oslo, Sweden gives a whole new meaning to the term “brainwashing.”

The study, published in the journal Science Translational Medicine, reveals that the brain has “great plumbing,” and that the purpose of the stream of fluid that flows through this plumbing system is to wash away buildups of proteins that have been associated with Huntington’s disease, Alzheimer’s disease, and other neurodegenerative disorders.

The body’s self-cleaning systems

Throughout most of the body, the task of cleaning up waste is handled by the lymphatic system, a series of vessels that wash away buildups of dead blood cells, excess plasma, debris, and other waste products. But the brain is not part of this system; instead of lymph, our brains are bathed in cerebrospinal fluid. Neuroscientists have for years assumed that this fluid cleaned up soluble waste by slowly becoming diffused through tissues to the nervous system, where the wastes are dumped into and handled by the blood system. This would be a slow and inefficient process.

Researchers in this new study have found that this long-held assumption may not be true, and that instead there is a second, much faster, and much more efficient system by which the brain keeps itself clean. Jets of fluid course through the brain in a previously unidentified set of channels, formed by glial cells that run parallel to the arteries that convey blood. Called by researchers the “glymphatic” system (a nod to the glial cells and the newly discovered system’s functional similarity to the lymphatic system), these vessels allow the cleansing fluid to not only cleanse the cerebrospinal fluid, but “recycle” it, returning up to 40% of it back to the brain.

The glymphatic system literally flushes toxins out of our brains. Fluid pumps through these channels at a relatively high speed, washing away waste products that build up between cells, and conveys them to major blood veins, where they can be removed from the body.

Why is this discovery important?

In the study, which was performed on mice because their brains are functionally similar to ours, they found that in mice who did not have these channels or in whom they did a poor job of clearing waste products, there was a 70% slower cleanup of amyloid proteins, which have been linked to Alzheimer’s disease. In a healthy brain, amyloid proteins are cleared out frequently. But in the brains of Alzheimer’s patients, they continue to build up and eventually form plaque that clogs the brain and causes the disease.

So scientists are excited about discovering this new way that the brain keeps itself clean, because if they can learn what regulates the flow of liquid through this self-cleaning system, they may be able to find a way to increase the flow, and thus either reverse neurodegenerative diseases like Alzheimer’s, or prevent them.

Obviously, this research is preliminary, and performed on mice. But its findings have allowed researchers to see the same mechanism at work in human brains. Dr. Maiken Nedergaard, one of the senior authors of the study, says, “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.”

In other words, now that the brain’s self-cleaning “plumbing system” has been found, scientists can begin to work on how to make it work even better.

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Juliette Siegfried, MPH

Juliette Siegfried, MPH, has been involved in health communications since 1991. Shortly after obtaining her Master of Public Health degree, she began her career at the National Institutes of Health in Bethesda, Maryland. Juliette now lives in Europe, where she launched ServingMed(.)com, a small medical writing and editing business for health professionals all over the world.

Juliette's resume, facebook: juliette.siegfriedmph, linkedin: juliettes, (+31) 683 673 767

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