Where does brain waste go?

A team of scientists in Washington has discovered that a slow wave of electricity pulses through the brain during sleep, pushing waste from deep within the brain to its surface.

The vein, which runs through the brain, acts as a tube to transport waste across the barrier separating the brain from the rest of the body, depositing it in the bloodstream to be filtered by the kidneys.

However, if this system stops working, which can happen with aging, traumatic brain injury, and chronic stress, waste products can accumulate in the brain, which may also allow immune cells to penetrate the organ, creating inflammation associated with degenerative brain disorders. .

Although the study was conducted on mice, scientists believe the results match research into the possible causes of Alzheimer's disease and other types of dementia.

The team, led by Jonathan Kipnis, a neurologist at Washington University in St. Louis, explained that waste exits the brain through the tough protective barrier without using the body's lymphatic system, a network that drains fluids throughout the body.

Scientists have discovered exit points around the brain from which cerebrospinal fluid, which carries waste, flows into the thick membrane surrounding the brain and spinal cord and into the bloodstream, where the body's lymphatic vessels then take over.

They reported that during sleep, neurons fire in synchronized rhythmic waves that generate the force to push cerebrospinal fluid across the blood-brain barrier.

“These neurons are miniature pumps,” said Dr. Li-Fengjiang Shi, the study’s lead author. “These neurons are miniature pumps. Synchronized neural activity promotes fluid flow and the removal of waste from the brain. If we can build on this process, there is potential to achieve prevention of neurological diseases, including This includes Alzheimer's and Parkinson's diseases, where excess waste accumulates in the brain and leads to neurodegeneration.”

In the same issue of Nature, MIT scientists expanded on the evidence that slow waves rid the brain of waste.

They found evidence that exposing mice with Alzheimer's disease to flashes of light and clicking sound at the same frequency as the brain's rhythm led to the appearance of pulsating signals in the brain that contributed to the release of cerebrospinal fluid from the organ, which carried amyloid protein, which accumulates in the brains of people with Alzheimer's disease.

It is noteworthy that insomnia impairs the flow of cerebrospinal fluid, as well as the elimination of waste products associated with neurodegenerative diseases.