Physical Fitness Tied to Lower Alzheimer's Risk

Physical fitness has been linked to a lower risk of Alzheimer's disease (AD), but even moderate levels of cardiorespiratory fitness offer some protection, new findings suggest.

"One exciting finding of this study is that as people's fitness improved, their risk of Alzheimer's disease decreased — it was not an all-or-nothing proposition," study investigator Edward Zamrini, MD, of the Washington VA Medical Center in Washington, DC, said in a news release.

The findings suggest that people can work toward making incremental changes and improvements in their physical fitness, which may help decrease their risk of dementia, Zamrini added.

The findings will be presented at the American Academy of Neurology (AAN) 2022 Annual Meeting in April.

Effective Prevention Strategy

Using the Veterans Health Administration database, the researchers identified 649,605 veterans (mean age, 61 years) free of AD and related disorders (ADRD) when they completed standardized exercise treadmill tests between 2000 and 2017.

They divided participants into five age-specific fitness groups, from least fit to most fit, based on peak metabolic equivalents (METs) achieved during the treadmill test: lowest-fit (METs, ±3.8), low-fit (METs, ±5.8), moderate-fit (METs, ±7.5), fit (METs, ±9.2), and highest-fit (METs, ±11.7).

In unadjusted analysis, veterans with the lowest cardiorespiratory fitness developed ADRD at a rate of 9.5 cases per 1000 person-years, compared with a rate of 6.4 cases per 1000 person-years for the most fit group (P < .001).

After adjusting for factors that could affect risk of ADRD, compared with the lowest-fit group, the highest-fit and fit groups were 33% and 26% less likely to develop ADRD, respectively, while the moderate-fit and low-fit groups were 20% and 13% less likely to develop the disease, respectively.

Fitness Group	Adjusted HR for ADRD (95% CI)
Low-fit	0.87 (0.85 to 0.90)
Moderate-fit	0.80 (0.78 to 0.83)
Fit	0.74 (0.72 to 0.76)
Highest-fit	0.67 (0.65 to 0.70)

The findings suggest that the association between cardiorespiratory fitness and ADRD risk is "inverse, independent, and graded," the researchers said in their conference abstract.

"The idea that you can reduce your risk for Alzheimer's disease by simply increasing your activity is very promising, especially since there are no adequate treatments to prevent or stop the progression of the disease," Zamrini added in the news release.

"We hope to develop a simple scale that can be individualized so people can see the benefits that even incremental improvements in fitness can deliver," he said.

The Next Vital Sign?

Commenting on the study for Medscape Medical News, Shaheen E. Lakhan, MD, PhD, a neurologist in Boston, Massachusetts, noted that "for decades and with increasing body of support from studies like this, we have known that preventing dementia is based on healthy behaviors for the brain including a proper diet (NASH and/or Mediterranean), exercise regimen (aerobic/cardio more than anaerobic/weight-lifting), sleep hygiene, and social and intellectual engagements."

"Frankly, what's good for the body is good for the brain," said Lakhan.

"It should be noted that the measure studied here is cardiorespiratory fitness, which has been associated with heart disease and resulting death, death from any cause, and now brain health," Lakhan said.

"This powerful predictor may in fact be the next vital sign after your heart rate and blood pressure from which your primary care provider can make a personalized treatment plan," he added.

"Accelerating this process, the ability to measure cardiorespiratory fitness traditionally from huge stationary machines down to wearables like a watch or ring, or even your iPhone or Android, is just on the horizon," Lakhan told Medscape Medical News.

"Instead of tracking just your weight, shape, and BMI, personal fitness may be tailored to optimizing this indicator and further empowering individuals to take charge of their health," he said.

The study was supported by the National Institute on Aging, the National Institutes of Health, the US Department of Veterans Affairs, the Washington DC VA Medical Center, and George Washington University. Zamrini and Lakhan have disclosed no relevant financial relationships.

American Academy of Neurology (AAN) 2022 Annual Meeting: Abstract 1475. To be presented April 2, 2022.

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