Scientists discover the brain’s drain

Scientists discover a new link between the brain and immune system.

It’s time to rewrite the neuroscience textbooks, after one of the basic tenets of neurology was overturned this week, opening up a whole new area of research into diseases of the brain.

This week a team of researchers at the U.S. National Institutes of Health revealed they had discovered the brain’s drain pipes. For years experts insisted the brain and the vessels of the lymphatic system were not directly connected.

(Lymphatic vessels are similar to veins and circulate white blood cells and cellular fluid.)

“It was dogma that there was no lymphatics in the brain,” said McGill neuropathologist Dr. Jason Karamchandani, who was not involved in the research. “It’s amazing to see in 10 years how we went from challenging dogma to confirming the actual truth.”

The brain is constantly creating waste that needs to be cleared, but scientists were never sure how exactly that happened.

Then in 2015 a team injected dye into the brains of mice and watched as it drained into vessels and then into the neck. They reported their findings in the journal Nature, and when Dr. Daniel Reich saw the discovery, he wondered if he could see the same thing in humans, using MRI.

After a series of experiments and post-mortem studies of brains, he found what he was looking for.

“We very quickly saw what I thought were lymphatic vessels, but it took us two years to fully convince ourselves,” Reich told us. And once he identified, for the first time, how the human brain drains into the lymphatic system, he had to make a decision — to tell or not to tell.

He considered holding off on the news until he had done enough research to offer some explanations about the relevance of the finding. But instead he decided to publish the finding immediately so other scientists could start asking questions.

Already scientists are calling him asking about how they can implement his technique.

“I hope we do find that this is important to human disease,” he said. “I think that the lymphatic vessels and their dysfunction might contribute in important ways to diseases of the brain that involve inflammation and buildup of toxic proteins.”

The next step is to take a close look at exactly what kind of communication is happening between the brain and the immune system through the lymphatic vessels. At McGill University, Karamchandani says the discovery opens up new areas of study.

“We probably underestimate the role of the immune system in many neuropathologies including neurodegenerative pathologies like Parkinson’s, ALS and Alzheimer’s,” he said.

“This is a confirmatory study that proves that the dogma of 10 years ago isn’t true, and it’s a novel way of linking the immune system and the central nervous system.”
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