The fitter you are, the lower your risk of Alzheimer’s disease

MINNEAPOLIS, MN. — When Fergie said she was working on her fitness in the hit song Fergalicious she wasn’t referring to Alzheimer’s. But, new research suggests she had the right idea after all. Scientists find the fitter you are; the lower your odds are of developing Alzheimer’s disease.

“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,” says study author Edward Zamrini, MD, of the Washington VA Medical Center in Washington, D.C., and a member of the American Academy of Neurology, in a press release. “So people can work toward making incremental changes and improvements in their physical fitness and hopefully that will be associated with a related decrease in their risk of Alzheimer’s years later.”

Adults who exercised the least had the greatest risk for developing Alzheimer’s

The study authors tracked the health of 649,605 military veterans for 9 years, with data taken from the Veterans Health Administration database. Health information included measuring each person’s cardiorespiratory fitness level — how well a person’s body can transport oxygen to muscles and how well the muscles absorb that oxygen while exercising. The average age was 61 years old, and there were no Alzheimer’s diagnoses at the beginning of the research study.

Researchers categorized participants into five groups depending on their fitness level on a treadmill test. The treadmill test measured their exercise capacity or the highest amount of physical exertion a person can handle. Middle-aged and older adults typically reach the highest fitness level with a brisk walk most days of the week or staying active for at least two and a half hours weekly.

Study participants in the lowest fitness category showed an Alzheimer’s development rate of 9.5 cases per 1,000 person-years. Alternatively, the fittest group showed a rate of 6.4 cases per 1,000 person-years. “Person-years” is a way of considering both the amount of participants in a study and the overall length of the research period.

Alzheimer’s diagnoses rates declined as fitness levels increased: The second least fit group displayed a rate of 8.5 cases. The middle group showed 7.4 cases, and the second most fit group had about 7.2 cases.

The team also considered other factors that could play a role in developing Alzheimer’s. But regardless, the fittest subjects were 33% less likely to develop Alzheimer’s disease than the least fit group. The second most fit group was 26% less likely to develop Alzheimer’s. The third most fit group was 20% less likely to have the disease. However, the least fit group had the highest risk compared to other groups of developing Alzheimer’s.

Exercise is one of many factors that influence the risk of Alzheimer’s

“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,” Dr. Zamrini concludes. “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.”

While the study shows the importance of exercise in preventing disease, the researchers note a person’s ethnicity could also influence their risk. In this study, most people were Caucasian, and future work will require a more diverse population sample to confirm the results.

The researchers will feature their work at the American Academy of Neurology’s 74th Annual Meeting.

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