A study of more than 650,000 US veterans found that those who performed the best on a treadmill test had a lower risk of dementia over 8.8 years of follow-up.
March 3, 2022
Being physically fit lowers your risk of developing dementia, according to one of the largest studies to test this idea to date.
Edward Zamrini at George Washington University in Washington DC and his colleagues studied the link between cardiovascular fitness and dementia in more than 650,000 people who had previously served in the US military.
Several studies have already shown that the fitter you are, the less likely you are to develop dementia, but Zamrini says those studies had small sample sizes and didn’t follow their participants long enough.
“Our study is different,” he says. “The cohort is large, with no symptoms of dementia at baseline and has a long follow-up.”
The participants in this study had an average age of 61 at the start and they were followed for an average of 8.8 years. At that time, 44,105 of them were diagnosed with dementia.
They were divided into five equal-sized groups based on their performance in a treadmill test at the start of the study, which measures the amount of oxygen used during exercise.
The team found that someone in the least fit group would reduce their risk of developing dementia by 13% if they moved to the second least fit group. If they joined the fittest group, their risk of developing dementia was reduced by 33%.
Most of the study participants were male, but a statistical test of the results from the 36,000 female participants showed no gender differences.
However, the results may have been affected by the fact that the participants were veterans. People in this group are more likely to have post-traumatic stress disorder or traumatic brain injury, which can exacerbate symptoms of dementia.
Although the study only included people who had no explicit symptoms of dementia at baseline, some people with dementia have no symptoms at the start of their condition, and therefore some participants may have started to develop dementia before participate in the study.
According to Zamrini, increased physical fitness can protect against dementia in several ways, such as improving blood flow to the brain and increasing connectivity between neurons. “It also reduces the risk of anxiety, depression, and other chronic disease risk factors,” he says.
Zamrini will present the results at American Academy of Neurology Annual Meeting in Seattle in April. Next, the team plans to search for biomarkers that can link cardiovascular fitness to the risk of developing dementia.
“This work has a clear demonstration of a progressive effect of aerobic fitness on dementia risk,” says Ozioma Okonkwo at the University of Wisconsin-Madison. Exercise can stimulate the production of a protein called brain-derived neurotrophic factor (BDNF), which is essential to our ability to learn and remember information, he says.
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