November 2012

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Health Capsule

Brain Cleaning System Discovered

Scientists have discovered a system that drains waste products from the brain. The finding may lead to new ways to treat brain disorders such as Alzheimer’s disease.

Our bodies remove dead blood cells and other waste products through a network of vessels called the lymphatic system. The brain, however, uses a different method. Cerebrospinal fluid cleanses brain tissue. Based on previous research, scientists suspected that nutrients and waste were carried away through a slow process called diffusion.

In a new study, scientists used a method called 2-photon laser scanning microscopy to analyze the movement of cerebrospinal fluid in living mouse brains. To their surprise, the researchers found that the fluid flowed along a series of channels surrounding blood vessels. They named this new system the “glymphatic system” because it is similar to the body’s lymphatic system but managed by cells in the brain called glial cells.

The scientists speculated that glitches in the glymphatic system might lead to the buildup of harmful waste in the brain. To test this idea, they injected a protein called amyloid beta into the brains of both healthy mice and mice with a faulty glymphatic system. The protein is known to play a role in human Alzheimer’s disease. Normal mice cleared amyloid beta rapidly from brain tissue. Mice with faulty glymphatic systems had much slower protein removal.

“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,” says Dr. Maiken Nedergaard of the University of Rochester Medical Center. “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.”