Exercise Isn’t Just for Muscles

January 10, 2024

Exercise can not only bulk up your muscles. It may also bulk up your brain. 

Those are the findings of a new report that analyzed exercise habits and MRI brain scans from 10,125 healthy men and women who ranged in age from 18 to 97. Their average age was 53.  

Among those in the study, 75 percent, or 7,606, engaged in at least 10 minutes of moderate to vigorous exercise one to seven days a week. On average, most of them exercised about four days a week. Activities included walking, running and playing sports. 

The researchers found that the more physical activity people got, the larger the volume of several brain regions critical for memory and learning. Regular exercise was linked to greater amounts of total gray matter, which is critical for cognition, and white matter, which facilitates communications between different areas of the brain. As brain cells die in Alzheimer’s disease, gray matter and white matter diminishes. 

Regular physical activity was also tied to greater volume in the hippocampus, a brain region long known to be vital to memory formation and recall, and regions of the cerebral cortex, which are important for learning and memory. The hippocampus is one of the first areas of the brain to be affected by Alzheimer’s disease, while the cerebral cortex undergoes damage as the disease progresses. 

“Our research supports earlier studies that show being physically active is good for your brain,” said Dr. Cyrus A. Raji, the study’s lead author and a professor at Washington University in St. Louis. “Exercise not only lowers the risk of dementia but also helps in maintaining brain size, which is crucial as we age.”  

Experts believe that greater brain volume may help to protect against the memory loss that accompanies aging and Alzheimer’s disease. As brain cells die, enough healthy brain cells remain to compensate, the thinking goes. 

Even modest amounts of physical activity appeared to benefit brain health. “We found that even moderate levels of physical activity, such as taking fewer than 4,000 steps a day, can have a positive effect on brain health. This is much less than the often-suggested 10,000 steps, making it a more achievable goal for many people,” said study author Dr. David Merrill, director of the Pacific Brain Health Center in Santa Monica, Calif.  

The findings, published in the Journal of Alzheimer’s Disease, add to growing evidence that exercise, and particularly aerobic exercise, can bulk up our brains, regardless of age. People in their 70s who participated in more physical exercise, including walking several times a week, had less brain shrinkage and other signs of aging in the brain than those who were less physically active. Other studies have shown that people who are active in midlife also tend to perform better on tests of memory and thinking skills than their peers who rarely exercise, and are nearly half as likely eventually to develop Alzheimer’s disease or mild cognitive impairment, a serious form of memory loss that may progress to full-blown dementia. 

Regular exercise may also help people who already have Alzheimer’s disease. Older men and women with early Alzheimer’s who regularly walk or engage in other physical activity tend to have less brain shrinkage than their less active peers, studies have found. Larger brain sizes in Alzheimer’s patients are associated with better memory. 

Alzheimer’s is a complex disease that likely depends on many factors, including the genes you inherit, and regular exercise is likely just one part of the preventive puzzle. While a daily walk around the mall or a swim at your local Y 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 Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.  

Source: Cyrus A Raji, Somayeh Meysami, Sam Hashem, et al: “Exercise-Related Physical Activity Relates to Brain Volumes in 10,125 Individuals.” Journal of Alzheimer’s Disease, Dec. 7, 2023


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