Scientists are beginning to understand how the brain eliminates waste products to stay healthy and defend against neurological diseases.
Two teams of Washington scientists have discovered signs that a slow wave of electricity that pulses through the brain during sleep pushes waste products, including the protein closely associated with Alzheimer’s disease, from deep in the brain to its surface. surface.
A vein that runs through the brain acts as a pipeline to transport waste products across the barrier that separates the brain from the rest of the body. This deposits them into the bloodstream for the kidneys to filter.
But if the elimination system stops working properly, which can happen with aging, in cases of traumatic brain injury and chronic stress, those waste products can build up in the brain.
It can also allow immune cells to penetrate the organ, causing inflammation linked to degenerative brain disorders.
The veins that run through the brain act as pipes that carry waste products across the barrier between the brain and the rest of the body and deposit them into the bloodstream to be filtered by the kidneys.
The study was conducted in mice, but researchers believe their findings are consistent with research into the possible causes of Alzheimer’s disease and other dementias.
In February, scientists led by Dr. Jonathan Kipnis, a neurologist at Washington University in St. Louis, answered the question how the brain removes waste through the rigid protective barrier without using the body’s lymphatic system, a network that drains fluids throughout the body.
The brain is not part of that system and its waste elimination pathway is known as the glymphatic system. Eliminates waste generated by energy-consuming metabolic processes (all chemical processes that continually work in the body to ensure its proper functioning), such as carbon dioxide, damaged proteins and dead cells.
Scientists discovered exit points around the brain from which cerebrospinal fluid, which carries waste, flowed into the thick membrane surrounding the brain and spinal cord and into the bloodstream, where the body’s lymphatic vessels were responsible for removing it. .
A few weeks later, that group of scientists expanded those findings even further, showing how that waste-laden liquid ends up at those exit points.
They reported that while the brain sleeps, neurons activate rhythmic and synchronized waves that generate force to evacuate cerebrospinal fluid through the brain and beyond the blood-brain barrier.
Dr. Li-Feng Jiang-Xie, a researcher at the University of Washington and lead author of the second study, saying: ‘These neurons are miniature bombs. Synchronized neural activity drives fluid flow and waste removal from the brain.
“If we can harness this process, there is a chance to delay or even prevent neurological diseases, including Alzheimer’s and Parkinson’s diseases, in which excess waste (such as metabolic waste and junk proteins) builds up in the brain and leads to to neurodegeneration”.
In that same number of NatureA team led by scientists at the Massachusetts Institute of Technology expanded the evidence that a slow wave removes debris.
They tested mice with Alzheimer’s and found evidence that exposing them to light flickers and sound clicks at the same brain rhythm frequency generated pulsating signals in the brain that moved CSF out of the organ.
That CSF carried amyloid protein, which accumulates in the brains of people with Alzheimer’s disease.
Dr. Jiang-Xie said, “We think the brain’s cleaning process is similar to washing dishes.”
«You start, for example, with a wide, slow and rhythmic cleaning movement to clean the soluble residues scattered on the plate.
“The range of motion is then reduced and the speed of these movements is increased to remove particularly sticky food residue from the plate.
‘Despite the different amplitude and rhythm of hand movements, the general objective remains the same: to remove different types of waste from the dishes.
‘Perhaps the brain adapts its cleaning method depending on the type and amount of waste.’
However, the lymphatic system deteriorates as we age, accumulating waste products such as amyloid proteins and tau tangles that contribute to cognitive decline and memory loss, as well as Alzheimer’s disease and dementia.
Changes in sleep patterns can also disrupt the normal waste elimination process. CSF flows more freely between cells while we sleep and the entire glymphatic process is optimized during sleep.
Without adequate sleep, CSF flow is impaired, as is the removal of waste products linked to neurodegenerative diseases.