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A Brisk Walk, Three Times a Week, May Help Keep the Brain Young

August 4, 2021

Older men and women who walked briskly for 40 minutes, three times a week, showed improvements in the white matter in their brains and scored higher on memory tests. Those who remained sedentary did not show such improvements. The changes were not dramatic. But the findings add to growing evidence that regular exercise helps to bolster the brain and may help to keep memory sharp into old age.

Scientists have long known that aerobic activities like walking, swimming, biking and running are good for brain health. Most of the earlier research focused on the brain’s gray matter, made up of billions of neurons that help us to move, think, converse, remember and do the countless other things that make us human. Regular aerobic exercise, the kind that boosts heart rates, is believed to help generating new neurons even in the adult, helping to counter the brain shrinkage that can occur with age. Less brain shrinkage is associated with better memory and thinking skills, and a lower risk of Alzheimer’s disease.

The current study, from researchers at Colorado State University, focused on the brain’s white matter, which acts as the brain’s wiring that connects and supports those billions of neurons. White matter, which gets its name from the white-colored fat that wraps around its cells, allows signals to be sent extremely quickly from one neuron to another, but tends to become frayed and depleted with age. Abnormal lesions also crop up in the white matter, a sign of brain aging. But, the researchers wondered, could regular exercise help to keep white matter healthy, the same way it does for gray matter?

So, for their study, which was published in the journal NeuroImage, they recruited 180 adults over 60 who were generally healthy but inactive. None had Alzheimer’s disease or other forms of dementia. Study participants got MRI brain scans to assess the health of their white matter. They also completed tests of aerobic fitness, as well as tests of memory and thinking skills.

The researchers divided them into three groups. One group began a walking program, walking briskly for 40 minutes three times a week. Another group met three times a week to learn and practice line dancing. The final group started a program of stretching and balancing exercises three times a week and served as controls.

After six months, the researchers again tested the participants brain health and aerobic fitness. Not surprisingly, the older men and women who walked or danced showed improvements in aerobic fitness. Brain scans revealed that their white matter looked a little less frayed and fuller, with fewer lesions, particularly in areas critical for memory that tend to shrink with age. The results were not dramatic, but they suggest that aerobic activity may have positive effects on the white matter of the brain.

The walkers and dancers also scored higher on tests of memory and thinking skills. The walkers showed the greatest cognitive improvements, though the researchers say this may have been because they tended to get more aerobic activity than the dancers, who spent much of their time watching instructors and learning new dances rather than actually dancing.

In contrast, those in the stretching group, who had not engaged in aerobic activities, did not show these improvements. Their white matter continued to show signs of fraying and aging. They also scored lower on tests of memory and thinking skills.

The findings add to growing evidence that aerobic exercise, which is good for the heart, also boosts brain health. A few brisk walks a week, the study suggests, may help to keep the brain healthy, including the white matter based on this study, and stave off memory decline with age. “The fact that we were able to show results in white matter in a clinical trial in only six months,” the researchers noted, suggests, “you don’t need to exercise your entire life to show some changes in your brain.”

Earlier studies have demonstrated the many benefits or walking, dancing and other aerobic activities, even for those who have memory problems. A year-long aerobic exercise program that mostly involved brisk walking improved blood flow to the brain in older adults at high risk of developing Alzheimer’s disease. Walking regularly also showed benefits for the brain in older men and women with mild cognitive impairment, a type of memory loss that often precedes Alzheimer’s disease. Another study of older men living in Hawaii who were in their 70s, 80s and 90s found that those who walked the least, less than a quarter mile a day, had nearly twice the risk for Alzheimer’s and other forms of dementia compared to men who walked the most, more than two miles daily.

Alzheimer’s is a complex disease that likely depends on many factors, including the genes you inherit. Walking, dancing and regular exercise are likely just one part of the preventive puzzle. While a daily walk around the mall or neighborhood track won’t guarantee a physically and mentally robust old age, it may help you to look, feel and act younger.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Andrea Mendez Colmenares, Michelle W. Voss, Jason Fanning, et al: “White Matter Plasticity in Healthy Older Adults: The Effects of Aerobic Exercise.” NeuroImage June 24, 2021

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