According to a preliminary study presented to the Congress of the American Academy of Neurology in February 2022, people in excellent physical shape are less likely to develop Alzheimer's disease than people who are less physically fit.

“An exciting finding from this study is that as fitness increased, the risk of Alzheimer's disease decreased,” said study author Edward Zamrini, MD, from Washington VA Medical Center in Washington, D.C., and a member of the American Academy of Neurology. “People can therefore work towards gradually changing and improving their physical fitness, and this will hopefully be linked to a corresponding reduction in Alzheimer's risk years later. ”

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The study involved 649,605 military veterans from the Veterans Health Administration database with an average age of 61 years, who were followed for an average of nine years. They did not have Alzheimer's disease at the start of the study.

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The researchers determined the participants' cardiovascular fitness, which is a measure of how well the body transports oxygen to the muscles and how well the muscles can absorb oxygen during physical exertion.

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The participants were divided into five groups, ranging from lowest to highest fitness levels. The fitness level was determined based on the participants' performance in a treadmill test. This test measures physical performance, i.e. the highest level of physical effort that a person can endure. Middle and older people can achieve the highest level of fitness if they walk briskly for at least two and a half hours most days of the week.

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The group with the lowest fitness level developed Alzheimer's disease at a rate of 9.5 cases per 1,000 person-years, compared with 6.4 cases per 1,000 person-years in the group with the best fitness level. Person years take into account both the number of people in a study and the time spent in the study. The case rate declined as fitness levels increased, with the second-least group having a rate of 8.5, the middle group 7.4 and the second-fittest group 7.2.

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Other factors that could influence Alzheimer's risk were considered in this study and found that people in the most athletic group had a 33% lower risk of developing Alzheimer's than people in the least athletic group. The second-highest fitness level group was 26% less likely to develop Alzheimer's disease, 20% lower in the middle group and 13% lower in the group with the lowest fitness level than in the group with the lowest fitness level.

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“The idea that you can reduce your risk of Alzheimer's disease simply by increasing your activity is very promising, especially as there are no adequate treatments to prevent or stop the progression of the disease,” Zamrini said.

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“We hope to develop a simple scale that can be customized so people can see the benefits that even gradually improving fitness can bring.”