A satisfactory night’s sleep has long been considered a cure for all diseases, especially in clearing harmful toxins from the brain.
Neuroscientists have long believed that deep sleep helps clear problematic debris from the brain, clearing many proteins and metabolites thought to play a role in the development of the nervous system. Alzheimer’s and other dementias.
That’s not exactly reassuring for the insomniacs among us. But conclusive evidence has always been difficult to come by, and a new study was published in the journal. Nature Neuroscience poured cold water on the theory. While sleep is still vital for many aspects of health, being active may actually play a much bigger role in toxin clearance, says professor Bill Wisden of the UK Dementia Research Institute, who led the study.
“We have shown that brain clearing during wakefulness is quite effective,” he says. “In general, being alert, active, and exercising can clear the brain of toxins more efficiently.”
This is undoubtedly good news for anyone struggling to make it through a solid seven hours a night. After all, a brisk half-hour walk is something most of us can accomplish even after a night of tossing and turning.
Wisden’s suggestion dovetails with a growing body of research findings in recent years showing how important exercise is for all aspects of the brain.
toxin cleanse
The role of exercise in removing waste from the brain is currently an active area of research in research laboratories around the world. The working theory involves certain shape-shifting brain cells, known as microglial cells, that can take on different personalities depending on your health status.
In some psychiatric conditions, such as schizophrenia and even Long Covid, the disease process causes microglia to take on a visible spiky form, causing inflammation and interfering with the natural functioning of the brain.
But researchers suspect that exercise may actively trigger microglia to take on a healthier anti-inflammatory outlook. This means they will act as beneficial scavengers, clearing away debris and keeping the synaptic connections between neurons clean and functioning properly.
Dr., an associate professor at Brock University in Canada, who runs a laboratory researching how exercise benefits the brain. “Microglia are there to investigate everything,” says Rebecca MacPherson. “We are exploring the idea that exercise stimulates them in a way that improves the way they clear metabolic products.”
brain fertilizer
Studies have repeatedly shown that being physically active reduces the risk of all types of dementia by 28%, and Alzheimer’s disease in particular, by 45%.
Over the years, scientists have conducted various experiments in which participants were randomly assigned to two different groups, with one group following an exercise program and the other group remaining sedentary. Nearly all reported that the exercise group performed better on cognitive tests, with the same trend seen in healthy participants, stroke survivors, and even Alzheimer’s patients.
Much of this is thought to be due to a molecule called brain-derived neurotrophic factor, or BDNF. This molecule has gained a reputation among neuroscientists as ‘brain fertiliser’ for its extraordinary ability to stimulate the growth of new neurons and strengthen the connections between them.
“While muscle contractions increase BDNF, your blood platelets actually store a lot of BDNF,” says MacPherson. “So with increased blood flow from exercise, your platelets can release more into the circulation.”
Through studies in cells and animals, MacPherson’s laboratory has even shown that BDNF prevents the accumulation of small fragments of beta-amyloid protein in the brain by altering the activity of different enzymes; This may explain why exercise helps reduce the risk of Alzheimer’s.
But BDNF isn’t the only beneficial molecule released when you exercise. A study in the journal last year Neuron It showed that exercise causes the production of a hormone called irisin, which can clear amyloid plaques.
Christiane Wrann, an assistant professor of medicine at Harvard Medical School who participated in the research, was so impressed by irisin that she is now looking to develop an artificial form of irisin as a therapeutic for a variety of neurodegenerative diseases, including Alzheimer’s and Parkinson’s.
“It’s a little hormone that works on neuroinflammation and plaque clearance, which makes it highly relevant to Alzheimer’s disease,” he says. “I think irisin has three or four properties that make it a really promising drug target.”
How much exercise and what intensity is best?
When asked this question, MacPherson gives a wry smile. “Everyone wants to know exactly what they need to do, and that’s a difficult question to answer,” he says.
NHS guidelines recommend that you do some form of aerobic exercise or physical activity that increases your heart rate for at least 30 minutes a day, five days a week.
MacPherson says BDNF production is related to exercise intensity, so your body will produce more when doing high-intensity types of activity, such as interval training. But he says it’s important for people to do what they think they can do, and that any exercise, no matter how light, will still provide some benefit for the body and brain.
“I think you have to think about how much time I have as an individual and what I enjoy.” says. “Even if you can only do moderate-intensity exercise, you get an increase in BDNF, and you also get an increase in blood flow, which delivers more oxygen and nutrients to the brain, which increases brain cell growth.”
The scientific reason why exercise boosts your mood
Exercise is also known to have the capacity to provide relief to people struggling with symptoms of depression, such as low mood or anhedonia, which refers to the loss of pleasure from previously rewarding activities.
Professor Jonathan Roiser, a cognitive neuroscientist at University College London, is leading a Wellcome-funded clinical trial to better understand why exercise is so beneficial for mental health.
“I have long been interested in the aspects of information processing that go wrong in depression and how they contribute to symptoms,” he says. “There are other symptoms that tend to cluster together with anhedonia, such as fatigue and difficulty making decisions, and there is some clue that exercise specifically targets such symptoms.”
Roiser’s trial will examine the greater benefits of aerobic exercise, in which participants are out of breath and working up a sweat, compared to gentle stretching and relaxation, in people with depression.
The aim is to get more evidence for some of the key theories behind how exercise benefits mental health; for example, stimulating the production of dopamine, which is related to motivation, and reducing inflammation.
“Many people with depression experience what we call chronic inflammation, which prevents dopamine neurons from firing and perhaps contributes to their symptoms,” he says. “So the anti-inflammatory effects of exercise are a fundamental part of how we think it works.”
As we discover more and more about how exercise protects the body, it may even lead to the emergence of a new class of drugs known as exercise mimetics, which may provide disabled and frail people with some of the benefits of physical activity.
But for the rest of us, researchers have a simple message: Whether you go to the gym or work out, taking time to stay active will keep your mind healthier for longer.
“Whether it improves mood or cognitive function, exercise is one of the best things you can do for your brain,” says Wrann.