This research adds to the evidence that one of the best ways to protect our minds may be physical activity.
“Exercise appears to be the key” to maintaining or even improving mental capacity as we age, says J. Carson Smith, a professor of kinesiology at the University of Maryland, College Park, who led the study. Stated.
How does exercise change the brain of the elderly?
As many of us know from harrowing experience, Mental agility often stutters with age, which begins in early middle age and accelerates from there. We find it increasingly difficult to remember our names, where we parked our car, whether we took vitamins this morning or yesterday.
Brain scans and other studies suggest that this decline is partly due to the fact that brain structure and function can wear out over time. Neurons weaken or die, weakening not only the connections between individual neurons, but also the connections between broader cellular networks in the brain.
Scientists have naturally wondered if this decline in brain function can be slowed or reversed.To investigate that pressing question, Smith and his colleagues Recruited 33 volunteers About half of those in their 70s and 80s have experience mild cognitive impairmentthe loss of thinking ability that often precedes Alzheimer’s disease.
everyone asked To complete a battery of physiological and psychological tests. In one experiment, researchers read a short story aloud and asked volunteers to tell it. In another case, volunteers lay quietly during a functional MRI scan that pinpoints electrical activity in many parts of the brain.
Half of the volunteers, including those with mild cognitive impairment, then began exercising, attending a supervised gym four times a week and briskly walking for about 30 minutes. Others remained inactive.
Four months later, everyone repeated the first test.
However, their results were different. Exercise participants, even those with mild cognitive impairment, scored better on cognitive tests, especially the story-repeating version. The sedentary volunteers did not.
Even more interesting is that the brains of those who exercised changed. Prior to this study, brain scans in elderly volunteers most often showed weak or scattered connections between and within major brain networks.
Our brains work best when a variety of different networks interact and connect to facilitate the formation of complex thoughts and memories. This process can be seen in brain scans, where connected brain networks light up in unison like synchronized Christmas lights.
Scans after four months of exercise showed that brain connections were stronger than before, with cells and entire networks glowing at the same time, a common trait of better thinking.
What we can learn from the mouse brain
But to better understand how exercise changes the brain with age, neuroscientists had to turn to mice.
Researchers have long known that mammalian brains, including ours, generate some new neurons during adulthood. neurogenesis.
Neurogenesis is important for brain health and is further enhanced by exercise.of the studywhen mice run, they send out two or three times as many new neurons as sedentary animals.
But unless these neurons survive and integrate into the broader brain network, they are not beneficial. In one study, Published in eNeuro in MayThe researchers let one group of young adult mice run and another group rested, infecting neonatal neurons and inserting a safe modified virus made to mark them with a jellyfish phosphorescent dye in the brains of all animals. injected into.
For the next six months, the runner continued to run and the sitter sat. The researchers then added another substance to the brains of the mice. The substance was designed to light up glowing cells that were produced when mice were young and first started running. It then invades wires, the serpentine dendrites that connect neurons to each other and to far-flung parts of the brain.
The researchers were able to use this substance as a marker to track the connections between each of these cells.
And not only did exercising mice generate more neurons than sedentary mice when they first started running, but as mice approached retirement age (in rodent terminology), the same We found that the cells were more intricately and extensively wired. animal brain networks.
Neurons in runners were better connected than those in sedentary animals.
What this means for young brains
What does this study mean for those of us who aren’t yet elderly or rats?
“I think this should be encouraging,” Smith said, especially for people worried that their brains are starting to slow down. His study found that even in sedentary older adults with alarming signs of cognitive decline, walking just a few hours a week improved brain connections and thinking.
But the findings also suggest that starting exercise at a young age may be even smarter. Henriette van Plaak, associate professor of biomedical sciences at Florida Atlantic University, said that young mice that ran probably accumulated a “cognitive reserve” of healthy neurons and connections more than inactive mice, and that has worked well over the years. Senior author of mouse studies.
Even better, start and don’t stop.
“Given the current state of science, it’s probably best to pursue physical activity when you’re young and continue into middle age and even old age,” said Russell Swerdlow, professor of neurology and director of the University of Kansas College of Alzheimer’s Disease. I think it’s a good idea,” he says. The Centers for Disease Research was not involved in the new study.
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