Just as regular exercise can keep aging bodies in shape, a recent study showed that aerobic exercise can keep the brain in shape. Aerobic exercise was shown to reduce central arterial stiffness and increase healthy blood flow to the brain in people with mild cognitive impairment (MCI). The study’s forty-eight participants (men and women aged 55 to 80) were randomly split into two groups – 19 in the moderate-to-vigorous “aerobic exercise” group, and 29 in the less physically intensive “stretching and toning” group. Both groups practiced their respective protocols three days a week for 30 minutes, slowly increasing to an average of five workouts a week for up to 40 minutes.
After a year, researchers retested the participants’ cognitive and physical health using cognitive exams, fitness tests, and magnetic resonance imaging (MRI) scans of the brain. In their evaluation, researchers noted greater aerobic capacity in the aerobic exercise group, and no improvements in the stretchers’ numbers. Both groups had slightly improved scores of memory and thinking, noting improved neurocognitive function. This falls in line with other studies which have shown that regular exercise can lower dementia risk by up to 90 percent.
However, there was one key difference between the groups. According to Rong Zhang, a researcher neurology professor at UT Southwestern Medical Center who oversaw the new study, “The most interesting difference we saw in the groups is that people who performed aerobic exercise had better brain perfusion and improved blood flow, which is related with a reduction of the arterial stiffness.”
As one ages, their arteries become stiffer, which is closely related to the progression of heart disease and increased heart strain, sometimes leading to failure, Zhang explained. Stiffer blood vessels and lower than average levels of blood to the brain have also been linked to MCI and dementia, though the overall cognitive decline is likely influenced by additional factors as well.
Zhang referred to the famous saying of Thomas Sydenham, the English physician: “A man is only as old as his arteries.”
“Same goes for women, of course,” he added. “We have proven that when we do exercise, the stiffness slows, which helps improve your brain perfusion. I think down the road that's potentially a good signal to encourage people.”
According to Zhang, the study’s results support the idea that improving vascular function benefits one’s brain function down the line, potentially aiding in the prevention of diseases like Alzheimer's. While he was encouraged by the trial’s outcome affirming that exercise gets more blood flowing to the brain, he believes a longer study could have yielded even more impactful results.
The adult human brain is just two percent of body weight. Despite its size, the brain requires a lot of energy to function. The more consistently the brain has healthy blood flow, the better it can flush away toxins and transport nutrients, including oxygen, to every cell in your body.
“The number one user of oxygenated blood in your entire body is your brain,” said Wendy Suzuki, professor of Neural Science and Psychology at New York University. “One of the things that changes most dramatically [through exercise] is the birth of new blood vessels. You are literally growing more blood vessels to get oxygenated blood to the brain, which makes brain function work a little better, because your brain cells are better oxygenated.”
Suzuki, who studies the effects of physical aerobic exercise on brain function, explains that while there are many factors at play when it comes to exercises’ ability to improve cognition, moving your body does increase growth factors in the hippocampus of the brain, a complex brain structure embedded deep in the temporal lobe that plays a critical role in the formation, organization, and storage of memories.
“Every time you workout, it’s basically like you are taking a watering can of growth factor and sprinkling it on your hippocampus,” she said. “But, just like a plant, your carrots don’t pop up in one day. It takes regular watering with this growth factor to get them to grow — but they will grow better with this growth factor, than if you are a couch potato.”
According to Suzuki these brand new hippocampal cells grow, activate, and become incorporated in memory circuits better than the cells that have been there since you were born. She called them “hyperactive teenage neurons,” because they’re young and have lots of energy, in comparison to older hippocampal cells.
The birth rate of new neurons generally declines when you develop mild cognitive impairment, dementia, or Alzheimer’s, but that potential, Suzuki said, remains hopeful into one’s seventh, eighth, and ninth decades. “Don't think that just because you're not a 20-year-old, your brain loses its capacity,” she assures. “It still has the ability to generate new brain cells in your hippocampus.”
Although producing new hippocampal cells takes time, there are other, more immediate brain benefits to reap from exercise. Suzuki called attention to the powerful effects that movement has on mood. She said walking for just ten minutes has been shown to improve one’s mood significantly and decreases anxiety levels, which can run high in people with dementia.
“I emphasize it, because those mood effects are easier to achieve and can be immediate,” she explained. “You don't have to get that aerobic. It could be simply from a leisurely walk outside. It's the first benefit… just do a little bit of movement and you just feel better.”