Cardio Fitness and Exercise Prevent Cognitive Decline

According to new research from The University of Texas at Dallas’ Center for Vital Longevity (CVL), older persons whose physical fitness is maintained by regularly engaging in intense exercise have brains that are more similar to younger adults.

In a study that was released online on April 27 and in the print edition of Neuroscience in June, Dr. Chandramallika Basak, associate professor of psychology in the School of Behavioral and Brain Sciences, served as the study’s lead author. The study discusses how challenging exercise and cardiorespiratory fitness help older adults’ brains make up for age-related changes by enhancing their capacity for difficult cognitive tasks.

The findings highlight the need to maintain physical fitness and engage in frequent vigorous exercise to maintain neurological health.

“Age is just one marker for cognitive health, and fitness can be a significant modifying factor,” said Basak, who directs the Lifespan Neuroscience and Cognition Lab in the CVL. “The brain activation patterns of high-fit older adults in our study resemble those of the young adults during a complex cognitive task that requires switching attention focus and updating memory rapidly. This suggests that physical fitness can significantly modify age-related changes in the brain.”

Using functional MRI, the researchers monitored changes in blood oxygen level-dependent signals as the 52 study participants carried out activities requiring various forms of cognitive control. According to Basak, there is little research on how physical exercise and cardiorespiratory fitness affect cognitive processes including switching, updating, and event anticipation, which were assessed in the study.

“Our findings suggest that a lifestyle involving moderate to strenuous physical activity may help maintain cognitive processing in the prefrontal cortex of older adults that matches that of younger adults, while cardiorespiratory fitness may preserve neurovascular health of posterior brain regions,” Basak said. “What we mean by strenuous physical activity is a level of physical activity that actually gets your heart rate up and increases your lung capacity.”

The study included younger volunteers with an average age of 26, in addition to comparing high-fit and low-fit older adults with a median age of 73 who were matched on several factors, such as blood pressure and general cognition.

“Our findings suggest that a lifestyle involving moderate to strenuous physical activity may help maintain cognitive processing in the prefrontal cortex of older adults that matches that of younger adults.” Dr. Chandramallika Basak, associate professor of psychology in the School of Behavioral and Brain Sciences.

“If you don’t have younger adults in your sample, you don’t know whether physical fitness is helping the brain activation patterns of high-fit older adults resemble that of younger adults, or whether these activations are engagement of additional brain regions that help compensate for the detrimental effects of brain aging,” Basak said.

Based on how frequently they self-reported participating in challenging physical activities such jogging, swimming, cycling, singles tennis, aerobic dancing, or skiing, the older participants were divided into high-fit or low-fit categories.

All participants completed challenging cognitive control exercises that required them to recall two sets of numbers that were displayed on two contrasting colored backdrops. Determining whether the number displayed matched or differed from the number they had previously seen on that color was up to the participants. Depending on whether the background colors were predictable or unpredictable, whether the numbers needed to be refreshed in memory or not, and whether the attention needed to switch between different pieces of information or remain focused on the same, the tasks become harder.

The dorsolateral prefrontal cortex, a traditional working memory and cognitive control region of the brain that is activated more as tasks get more challenging, was found to be largely employed by young adults, according to fMRI scans.

Like firefighters responding to a multiple-alarm fire, the brain generally mobilizes its resources when a task becomes too challenging for one area to handle alone.

“Younger brains are more efficient. They don’t need to work hard,” Basak said. “They only need to use these extra resources when things get more difficult.”

Even when the job is straightforward, older brains over activate the dorsolateral prefrontal cortex.

“When a task is extremely difficult, this region’s activation typically drops in older adults whereas younger adults may still show an increase. This pattern, also known as the CRUNCH model, is a neural marker indicating that the older participants are not able to modulate this brain region anymore to support their task performance,” Basak said.

The CRUNCH (Compensation-Related Utilization of Neural Circuits Hypothesis) model does not, however, hold true for all aging persons, according to the study’s findings.

“What we found is that these high-fit older adults overactivated the dorsolateral prefrontal cortex only at moderate levels of task difficulty, whereas low-fit older participants used this region even for the simplest version of the task,” Basak said. “Moreover, high-fit older adults compensated by activating another brain region, the superior parietal lobe”.

“We found such protective effects in those subjects who regularly engaged in strenuous activity and exhibited high cardiorespiratory fitness, which compensates for the decline of cognition we normally see with age,” Basak continued. “Our results suggest that the CRUNCH model needs to be modified to take into account the protective effect of physical fitness on the aging brain.”

Young individuals and high-fit older subjects showed distinct variations in task performance and brain activity, but these differences were substantially lower than those between high-fit and low-fit older people.

“A lot of things get worse as we get older, and some of them can have an independent impact over and beyond just aging,” Basak said. “We showed that high levels of physical activity and high cardiorespiratory fitness allow you to recruit additional brain regions that help you compensate and maintain accuracy levels. So it seems that there are independent effects of fitness that may allow us to counteract some effects of aging.”

Paulina Skolasinska MS’21, a doctoral candidate in cognition and neuroscience, and Shuo Qin PhD’19, a current postdoctoral research researcher at the National University of Singapore, are additional authors on the work.

The work was funded by the Advanced Imaging Research Center, a partnership between the UT Southwestern Medical Center, UT Dallas, and other North Texas institutions, as well as the National Institute on Aging (R56AG060052) of the National Institutes of Health.

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