Scientists discover the brain is part of the lymphatic system

The human body is miraculous, and as much as we now know about how it functions, there is still so much we don’t know. But one thing we’ve known since just about the 17th century is that we all have a lymphatic system that drains waste and fluids from our body, just like a sewer does for the environment. This process plays a vital role in our immune system, helping us get rid of things in our body that could make us sick.

What we haven’t known, however, is just how extensive this lymphatic system really is. It’s long been thought that the brain has been excluded from this bodily plumbing, but researchers have now confirmed the presence of lymphatic vessels in human brains.

What does this mean exactly? Well, it could open the door to new insights into a variety of neurological disorders, such as multiple sclerosis and Alzheimer’s, and help us understand how our immune system influences our brain and behavior.

This discovery was made when researchers at the National Institutes of Health scanned the brains of healthy volunteers and found lymphatic vessels in a membrane that surrounds the brain and nervous system:

Because multiple sclerosis seems to be triggered by a glitch in the immune system, the discovery of lymphatic vessels in the brain may lead to a better understanding of the disease. The same goes for Alzheimer’s, which involves a large accumulation of protein chunks in the brain.

“We think they (protein chunks) may be accumulating in the brain because they’re not being efficiently removed by these vessels,” Jonathan Kipnis, a professor in the Department of Neuroscience and director of the University of Virginia’s Center for Brain Immunology and Glia, told UVA Today.

Even more interesting, the research also shows our immune system might affect our behavior. And this goes beyond feeling grumpy when you have a cold. It shows how our immune systems may play a role in conditions like depression, autism and schizophrenia. When researchers switched off one immune molecule in mice, they found that the way the animals behaved and interacted with each other changed, suggesting that if different parts of the immune system aren’t functioning correctly in humans, it may lead to behavior-type disorders.

To show this new discovery in action, the team constructed a 3-D rendering of one of the channels in one volunteer’s brain and posted it to YouTube. Check it out for yourself:

Researchers plan to investigate this new discovery even further to figure out whether the lymphatic system works differently in patients with neurological diseases.

“For years we knew how fluid entered the brain. Now we may finally see that, like other organs in the body, brain fluid can drain out through the lymphatic system,” said Daniel S. Reich, M.D., Ph.D., senior investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study. “We hope that our results provide new insights to a variety of neurological disorders.”

[h/t: Science Daily]