When neurons in your brain are active, they create waste.
Nick Vesey / Science Photo Library / Alamy
As we enjoy the holiday season, many will already be planning a detox in the new year: perhaps reducing screen time or abstaining from alcohol. I recently wondered if you could apply the same logic to the brain: is there anything I can do when the fun is over to help clear out my cognitive cobwebs?
In fact, the brain does its own work. detoxification every day – cleansing the body of metabolic waste products that would otherwise accumulate and cause harm. But can we help this process? And if so, could it protect us from age-related cognitive decline and dementia?
Let's start by introducing the brain cleansing team, starting with glymphatic system. This relatively recently discovered waste pathway sucks up unwanted proteins and other debris from the spaces between neurons and carries them into the cerebrospinal fluid (CSF).
“CSF circulates just like water in a dishwasher,” says Maha Alattar at Virginia Commonwealth University in Richmond.
The fluid then releases the waste into the lymph nodes and from there into the veins before it is eventually eliminated from the body.
How the glymphatic and lymphatic systems connect is not well understood, but researchers are increasingly interested in how to optimize the efficiency of the glymphatic system because they believe it is. may be important in preventing cognitive decline and supporting healthy aging. This is partly because the accumulation of metabolic waste in the brain is associated with deterioration of cognitive healthincreased risk of developing dementia and accelerating symptoms Alzheimer's disease And Parkinson's disease.
“The glymphatic system is interesting,” says Nand Kumar Narayanan at the University of Iowa Health Care. “There are many great ideas and research efforts aimed at understanding the glymphatic system, measuring it carefully, and using those measurements to better understand human health and disease.”
Strengthening Your Brain's Waste Removal System
So is there anything we can do to make this waste disposal system work more efficiently? Recent research has shown that lifestyle factors may be our best tools.
“The most well-established way to improve glymphatic clearance is sleep,” says Lila Landowski at the University of Tasmania in Hobart, Australia.
The glymphatic system is mostly shut down during waking hours and works best at night. For example, in mice, cerebrospinal fluid flow increases by about 60 percent during sleep, which greatly enhances the removal of beta-amyloid, a protein associated with Alzheimer's disease.
Although research has not yet definitively proven that strengthening the glymphatic system prevents dementia, “the hypothesis is supported by the fact that factors that reduce glymphatic clearance—sleep disturbance, glymphatic dysfunction, and a sedentary lifestyle—are all associated with an increased risk of neurodegenerative diseases and cognitive decline,” says Landowski.
Interestingly, the way you sleep can also promote glymphatic drainage. In 2015 Helen Benvenistenow at Yale Medical School, and her colleagues found that Side sleeping was more effective at improving glyphatic clearance in mice than sleeping on your back or front. No one has tested this in humans yet, but since many types of dementia are closely linked to sleep disturbances, Benveniste and her team suggest that how you sleep could be a useful part of our anti-dementia arsenal.
Other ways to drain your brain
Increasing evidence suggests that other lifestyle factors, such as exercisealso improves glyphatic function. In April, 37 adults underwent brain imaging before and after participating in either one workout or a 12-week cycling regimen that included 30-minute sessions three times a week. Only the group that trained for 12 weeks showed increased glymphatic drainage.
“Studies in mice show that glymphatic clearance approximately doubles after 5 weeks of exercise compared to sedentary mice,” says Landowski, “but shorter periods of time have not yet been studied in humans.”
But a closer look at the glyphatic system may reveal other ways to improve its flow. The lymphatic vessels through which cerebrospinal fluid is drained are located deep in the neck, which makes direct manipulation of them difficult, but recently Go Young Ko from the Korea Advanced Institute of Science and Technology in South Korea and colleagues discovered another network of lymphatic vessels just below the skin on the face and neck of monkeys and mice.
In mice, gently stroking down the face and neck for one minute increased CSF flow threefold, effectively restoring the reduced CSF flow seen in older animals to a more youthful state.
Similar vessels have been found in human cadavers, raising the possibility that facial or neck massage may increase cerebrospinal fluid flow in us too and thereby help with glymphatic clearance, but more research is needed to determine whether this occurs and whether this increased flow may protect against neurodegenerative diseases.
Convincing Evidence for Yogic Breathing
One type of exercise that should not be overlooked is yogic breathing, he says. Hamid Jalilyan at the University of California, Irvine. There is now well-documented evidence that diaphragmatic breathing may increase cerebrospinal fluid velocitywhich, according to Jalilian, is enough to start the glymphatic “rinse cycle.”
Diaphragmatic breathing is a deep breathing technique in which you inhale through your nose while pushing your belly outward to push your diaphragm down while your chest remains relatively still. Exhaling through pursed lips and drawing the belly inward completes the cycle.
Unexplored Potential
However, despite the enthusiasm of some researchers, our understanding of the complex workings of the glymphatic system is still in its infancy, and not everyone thinks we know enough to actively prescribe interventions. “We're definitely not at a point where we can predict how specific interventions, such as exercise, will affect the glyphatic system. There are some studies in mice and small groups of people, but no large definitive studies,” warns Narayanan.
But even he is optimistic. “The potential is huge, but we need to do these studies carefully and carefully.”
So for now I'll focus on what I should be doing anyway – sleeping well and exercising regularly. These habits are already important for overall health, but if the glyphatic research is confirmed, they may prove even more important for keeping my brain sharp not only in the new year, but well into the future.
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