Courtesy of Human Connectome Project
White matter connectivity illustrated by the Human Connectome Project. 
Source: Courtesy of Human Connectome Project

A recent study from Boston University Medical Center reports that improving physical fitness may benefit the integrity of the brain's white matter for older adults. 

The April 2015 study, "Cardiorespiratory Fitness Is Associated with White Matter Integrity in Aging," appeared online in the Annals of Clinical and Translational Neurology. This was the first study to identify a correlation between physical fitness and improved brain structure in older adults. 

In a previous Psychology Today blog post, "Why Is Physical Activity So Good For Your Brain?" I wrote about research showing that physical activity improved the white matter integrity of physically fit children aged 9 to 10 and also in “low fit” participants aged 60 to 78.

What Is White Matter? 

​White matter helps the gray matter of various brain regions communicate more fluidly and efficiently. The new BU research suggests that physical activity may be a valuable prescription for reducing age-related deterioration of brain structure and function.

During early childhood, scaffolding is laid down between various brain regions that creates the foundation for future neural networks that will either be pruned or strengthened through neuroplasticity. The key to learning and memory is based on the “fire and wire” principle that creates brain connectivity between brain regions using white matter connectivity.

Wikimedia/Public Domain
Source: Wikimedia/Public Domain

The brain wants to be streamlined. Through plasticity, your brain cuts the connections between seemingly unnecessary networks and strengthens the connections between brain regions that require more robust lines of communication.

You can imagine the billions of neural connections within, and between, the gray matter of various regions of your brain connected via white matter—similar to the old phone wires seen in this illustration of telecommunication lines in New York City circa 1890.

Cardiorespiratory Fitness Is Linked to Structural White Matter Integrity

The BU researchers compared younger adults (age 18-31) to older adults (age 55-82). All participants had MRIs taken of their brains and their cardiorespiratory (heart and lung) fitness was measured while they exercised on a treadmill.

The researchers found cardiorespiratory fitness was positively linked to the structural integrity of white matter fiber bundles in the brain in the older adults. Improved integrity of white matter is literally like having a fiber-optic cable as opposed to analog wiring.  

In a press release, corresponding author Scott Hayes, PhD, assistant professor of psychiatry at Boston University School of Medicine and the associate director of the Neuroimaging Research for Veterans Center at the VA Boston Healthcare System said,

We found that higher levels of cardiorespiratory fitness were associated with enhanced brain structure in older adults. We found that physical activities that enhance cardiorespiratory fitness, such as walking, are inexpensive, accessible and could potentially improve quality of life by delaying cognitive decline and prolonging independent function.

According to the researchers, these results provide evidence of a positive association between physical fitness and brain structure in older adults. Hayes said, "We hope this study provides additional motivation for older adults to increase their levels of physical activity, which positively impacts health, mood, cognition and the brain."

Courtesy Human Connectome Project
Source: Courtesy Human Connectome Project

The authors emphasize that additional research is needed to monitor how specific changes in cardiorespiratory fitness relate to changes in white matter brain structure over a period of time.

In the future, when health providers are prescribing fitness activities to improve brain structure, the researchers believe it will be helpful to better understand the impact of specific exercise programs (such as strength, aerobic or combined training) or dose of exercise (frequency, intensity, duration) on white matter integrity. 

Older Adults Can Optimize Brain Function by Improving Fitness

A separate study, released in July 2015, offers some answers to the questions posed by Hayes et al. The study by University of Kansas Medical Center found that older adults can improve brain function by raising their fitness level.

Jeffrey Burns, M.D., professor of neurology and co-director of the KU Alzheimer's Disease Center, led a six-month trial conducted with healthy adults ages 65 and older who showed no signs of cognitive decline.

The results of the study, "Dose-Response of Aerobic Exercise on Cognition: A Community-Based, Pilot Randomized Controlled Trial," were published in the journal PLOS ONE.

The researchers set out to determine the ideal amount of exercise necessary to achieve brain benefits. Trial participants were placed in a control group that did not have monitored exercise, or they were put into one of three other groups.

One group moderately exercised for the recommended amount of 150 minutes per week, a second exercised for 75 minutes per week, and a third group exercised for 225 minutes per week.

All groups who exercised saw some benefit. Participants who exercised more saw more benefits. Interestingly, the brain arear that showed particular improvement was visual-spatial processing, which is the ability to perceive where objects are in space and how far apart they are from each other.

Participants who exercised also showed an increase in their overall attention levels and ability to focus. In a press release Burns said, "Basically, the more exercise you did, the more benefit to the brain you saw. Any aerobic exercise was good, and more is better." 

The KU researchers conclude that physical activity that actually improves your overall fitness level may be necessary to optimize brain function as you age. 

If you'd like to read more on this topic, check out my Psychology Today blog posts, 

© Christopher Bergland 2015. All rights reserved.

Follow me on Twitter @ckbergland for updates on The Athlete’s Way blog posts.

The Athlete’s Way ® is a registered trademark of Christopher Bergland.

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