Increased Dementia Risk Linked to Poor Cardiorespiratory Fitness

We all know that slogging to the gym on a regular basis has positive effects on our future well-being. While this sentiment should seemingly be a motivating factor to keep oneself in shape, it tends to do little in the way of inspiring us to get out of bed early on those chilly winter mornings. Well, perhaps some new data from investigators at UT Southwestern's O'Donnell Brain Institute could cause a greater sense of urgency to improve our overall health. The researchers have just released new data that adds to the growing amount of evidence that exercise improves brain health and could be a lifesaving ingredient that prevents Alzheimer's disease (AD). Findings from the new study were published recently in the Journal of Alzheimer’s Disease, in an article entitled “Cardiorespiratory Fitness and White Matter Neuronal Fiber Integrity in Mild Cognitive Impairment.”

“This research supports the hypothesis that improving people's fitness may improve their brain health and slow down the aging process,” explained lead study investigator Kan Ding, M.D., a neurologist at the Peter O'Donnell Jr. Brain Institute.

The UT Southwestern team focused their research white matter within the brain, which is comprised of millions of bundles of nerve fibers used by neurons to communicate. Moreover, the researchers enrolled older patients at elevated risk to develop AD who had early signs of memory loss, or mild cognitive impairment (MCI). The scientists subsequently determined that lower fitness levels were associated with weaker white matter, which in turn correlated with lower brain function.  

Interestingly, unlike previous studies that relied on study participants to assess their own fitness, this study objectively measured cardiorespiratory fitness with a scientific formula called maximal oxygen uptake. Scientists also used brain imaging to measure the functionality of each patient's white matter. Additionally, patients were then given memory and other cognitive tests to measure brain function, allowing scientists to establish strong correlations between exercise, brain health, and cognition.

“Evidence suggests that what is bad for your heart is bad for your brain,” noted senior study author Rong Zhang, Ph.D., a professor at UT Southwestern and director of the cerebrovascular laboratory in the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas. “We need studies like this to find out how the two are intertwined and hopefully find the right formula to help prevent AD.”

The ongoing trial, which includes six medical centers across the country, aims to determine whether regular aerobic exercise and taking specific medications to reduce high blood pressure and cholesterol levels can help preserve brain function. It involves more than 600 older adults at high risk to develop AD.

While this study builds upon prior investigations linking healthy lifestyles to better brain function—including a 2013 study from Dr. Zhang's team that found neuronal messages are more efficiently relayed in the brains of older adults who exercise—it also leaves plenty of unanswered questions about how fitness and AD are intertwined. For instance, what fitness level is needed to notably reduce the risk of dementia? Is it too late to intervene when patients begin showing symptoms?

“A lot of work remains to better understand and treat dementia,” concluded Dr. Ding. “But, eventually, the hope is that our studies will convince people to exercise more.”