How to Keep Your Brain Healthy with Exercise

Poor physical fitness in middle age may result in dementia-linked brain shrinkage. Here's how to keep your brain healthy and young through exercise.

If you lead a sedentary lifestyle and avoid regular exercise, it could be more than your abs that are suffering. 

Being a couch potato may take a serious toll on your brain and could even contribute to developing dementia in later life.

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Alzheimer's and brain shrinkage

While some change in the brain size is associated with normal aging, scientists have found that people with Alzheimer’s disease typically have significant shrinkage in parts of their brains. Now research from Boston University has linked poor physical fitness to an increased loss of brain volume over the course of 20 years.

"We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain aging," said Nicole L. Spartano, PhD, lead author and a postdoctoral fellow at Boston University School of Medicine.

Spartano and her colleagues used data on 1,583 people enrolled in the Framingham Heart Study. None of the study participants, who had an average age of 41, were diagnosed with dementia or heart disease when the Framingham project started 20 years ago, and each took a stress test to measure their fitness levels. Then, two decades later, the same people took another stress test and were given MRI brain scans, too.

Poor fitness = loss of brain volume

When the Boston University team analyzed the tests, they found an association between poorer fitness levels and loss of brain volume even after excluding results of the participants who had developed heart disease or who were taking medication (beta blockers) for high blood pressure or heart problems. For every eight units of lower physical performance (measured by the maximum amount of oxygen a person is able to use in one minute) on the treadmill test, brain volume on MRIs was smaller — equivalent to two years of accelerated brain aging. 

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The researchers also looked to see whether exaggerated blood pressure fluctuations during exercise were linked to structural changes in the brain. 

“Small blood vessels in the brain are vulnerable to changes in blood pressure and can be damaged by these fluctuations," Spartano explained. "Vascular damage in the brain can contribute to structural changes in the brain and cognitive losses. People with poor physical fitness frequently respond to exercise with higher blood pressure and faster heart rate responses compared to people with better fitness.”

The Boston University study revealed the study participants whose blood pressure and heart rate spiked to a higher rate during exercise were more likely to have smaller brain volumes.

How to keep your brain healthy

Although the research findings don’t prove that not being fit causes brains to get smaller, it does show a strong association and suggests yet another reason — along with reducing risk factors for heart disease, type 2 diabetes, and a host of other chronic ills — why regular exercise is a smart part of a healthy lifestyle. Working on physical fitness at mid-life can be an important step toward ensuring healthy aging of the brain, the researchers concluded. 

"Many people don't start worrying about their brain health until later in life, but this study provides more evidence that certain behaviors and risk factors in midlife may have consequences for brain aging later on," Spartano said. 

Even older adults who are having memory problems could potentially benefit from getting in better shape. A study from University of Maryland School of Public Health researchers found improving fitness in elders through a moderate intensity exercise program resulted in an increase in the outer layer of the brain that typically shrinks with Alzheimer's disease, the cortex. 

What’s more, this impact of improved fitness on the brain was found in both healthy older adults and those diagnosed with mild cognitive impairment (MCI), which develops in the early stage of Alzheimer's disease. 

"Exercise may help to reverse neurodegeneration and the trend of brain shrinkage that we see in those with MCI and Alzheimer's," said J. Carson Smith, PhD, associate professor of kinesiology at the University of Maryland and senior author of the study.

"Many people think it is too late to intervene with exercise once a person shows symptoms of memory loss, but our data suggest that exercise may have a benefit in this early stage of cognitive decline."

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