Wang Jimin
Wang Jimin
[New Sancai Compilation First Release] A unique look inside the human brain may help explain how it removes waste products, such as those that may accumulate and lead to Alzheimer's disease.
Brain cells use a lot of nutrients, which means they produce a lot of waste. Scientists have long thought that the brain has special channels to remove cellular waste, especially during sleep—and they could see this happening in mice. But there is only indirect evidence that humans have a similar system.
Now, using a special imaging technique, researchers have finally discovered a network of tiny waste-clearing channels in the brains of living people.
"I doubt it," said Dr. Juan Piantino of Oregon Health and Science University, whose team reported the findings on Monday. "We needed this article to show that this happens in humans too."
The research was published in the journal Proceedings of the National Academy of Sciences.
The brain is very active during sleep. One reason seems to be that it needs a deep cleaning. This is cause for concern because, while sleep deprivation can disrupt people's thinking, chronic sleep deprivation is also considered a risk factor for dementia.
So how does the brain cleanse itself?
More than a decade ago, scientists at the University of Rochester first reported the discovery of a network they called a "lymphatic system." is beta-amyloid, which is cleared more quickly when the animal sleeps.
It's unclear exactly how this network works, although some studies suggest that the pulsation of blood vessels helps move waste-removing fluid where it's needed.
But such a system is hard to find in people. Piantino said regular MRI scans can spot some of the fluid-filled channels but can't show their function.
So his team in Oregon injected the tracer into five patients who were undergoing brain surgery and needed more advanced forms of MRI. The tracer "lit up" under these scans, and sure enough, 24 to 48 hours later, instead of randomly moving around the brain, it was moving through these channels, as previous studies had found in mice.
Dr. Maiken Nedergaard of the University of Rochester predicts that this is a small but potentially important study that will increase interest in the relationship between brain waste removal and people's health.
But to test whether better sleep or other treatments actually promote waste removal and improve health, "I have to be able to measure people's lymphoid function," added Dr. Jeff Iliff of the University of Washington, who Helped pioneer waste removal research. The question is whether the new study might point to a way to measure that.
Sleep isn't the only problem. For example, animal studies suggest that an old blood pressure drug now used to treat post-traumatic stress disorder may improve lymphoid function, which Iliff and colleague Elaine Peskind, Ph.D., are about to study in some patients. .
Larger studies in healthy people are needed, and Piantino's lab, which focuses on sleep health, hopes to find simpler, more non-invasive tests.
(Compiled by: Wang Jimin)
(Editor: Jiang Qiming)
(Source of the article: Compiled and published by New Sancai)
