The rhythmic waves of blood and cerebrospinal fluid (CSF) that occur when we are sleeping, appear to function much like a washing machine’s rinse cycle, which may help to clear the brain of toxic waste on a regular basis.
Every 20 seconds, a wave of fresh cerebrospinal fluid rolls into the sleeping brain. These slow, rhythmic blasts, described for the first time in the Nov. 1 Science, may help explain why sleep is so important for brain health.
Studies on animals have shown that the fluid, called CSF, can wash harmful proteins, including those implicated in Alzheimer’s disease, out of the brain. The new results give heft to the idea that a similar power wash happens in sleeping people.
The findings, published recently in the journal Science, are the first to suggest that the brain’s well-known ebb and flow of blood and electrical activity during sleep may also trigger cleansing waves of blood and CSF. While the experiments were conducted in healthy adults, further study of this phenomenon may help explain why poor sleep or loss of sleep has previously been associated with the spread of toxic proteins and worsening memory loss in people with Alzheimer’s disease.
From Science News via YouTube »
During non-REM sleep, oxygen-rich blood (colored red) flows out of the brain just before a wave of cerebrospinal fluid (blue) rolls in, entering from a lower part called the fourth ventricle. That cerebrospinal fluid may help clean harmful proteins out of the brain.
It is by now well established that exercise has positive effects on the brain, especially as we age.
Less clear has been why physical activity affects the brain in the first place.
Key events in the evolutionary history of humans may have forged the link between exercise and brain function.
Cognitively challenging exercise may benefit the brain more than physical activity that makes fewer cognitive demands.
People often consider walking and running to be activities that the body is able to perform on autopilot. But research carried out over the past decade by us and others would indicate that this folk wisdom is wrong. Instead exercise seems to be as much a cognitive activity as a physical one. In fact, this link between physical activity and brain health may trace back millions of years to the origin of hallmark traits of humankind. If we can better understand why and how exercise engages the brain, perhaps we can leverage the relevant physiological pathways to design novel exercise routines that will boost people’s cognition as they age—work that we have begun to undertake.
Sitting for hours without moving can slow the flow of blood to our brains, according to a cautionary new study of office workers, a finding that could have implications for long-term brain health. But getting up and strolling for just two minutes every half-hour seems to stave off this decline in brain blood flow and may even increase it.
Delivering blood to our brains is one of those automatic internal processes that most of us seldom consider, although it is essential for life and cognition. Brain cells need the oxygen and nutrients that blood contains, and several large arteries constantly shuttle blood up to our skulls.
What these results tell us about the role exercise might play in slowing the development of Alzheimer’s is difficult to nail down. While studies like this suggest that exercising more strengthens the brain against the debilitation leading to severe dementia, definitive answers are still elusive. We don’t know, for example, the amount of exercise that makes a difference, if specific types of exercise are better than others, or whether starting exercise later in life can forestall the progression of dementia.
What we do have are solid indications that we should think of exercise and brain health in a similar way to exercise and heart health. Some of the same benefits exercise provides the heart—like improved blood flow and lower inflammation—also benefit the brain. More evidence along those lines keeps coming, further supporting the case that staying active is a better policy for brain health than the alternative.
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