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Increasing physical activity in midlife or later may reduce the chances of developing dementia by up to 45%, according to a recent study published in JAMA Network Open.
Researchers at the Boston University School of Public Health analyzed data from more than 4,300 people in the Framingham Heart Study Offspring, all of whom were dementia-free at the start of the study.
The individuals completed a questionnaire reporting their amount of sleep and level of physical activity (sedentary, slight, moderate or heavy), according to the study report.
Study design and key findings
The researchers analyzed the individuals’ physical activity throughout three life stages — early adult (ages 26-44 years), midlife (45-64 years) and late life (65-88 years).
They followed the participants for an average span of 37.2, 25.9 and 14.5 years, respectively, to monitor the onset of Alzheimer’s and other types of dementia.
Those in the top two quintiles of midlife physical activity were associated with a 40% lower all-cause dementia risk over a 26-year period, compared to those with the lowest activity level.
People in the top two quintiles of late-life physical activity were associated with a 36% to 45% lower dementia risk over 15 years.
“These results may help to inform more precise and effective strategies to prevent or delay the onset of dementia in later life, and support evidence that the benefits of physical activity on the brain may extend to earlier in life than previously thought,” study author Phillip Hwang, Ph.D., from the Department of Epidemiology at the Boston University School of Public Health, told Fox News Digital.
Higher activity in midlife was associated with lower dementia risk only in people without APOE4, a genetic variant linked to higher Alzheimer’s risk.
However, this was not the case with the late-life higher activity group, which showed reduced dementia risk among both APOE4 carriers and those without the gene, according to the study.
The exercise-brain link
“There are several possible mechanisms through which physical activity is thought to lower the risk of dementia, such as improving brain structure and function, reducing inflammation and exerting benefits on vascular function,” Hwang told Fox News Digital.
Physical activity may also directly impact Alzheimer’s disease pathology, such as the buildup of toxic beta-amyloid in the brain, according to the researcher.
“These potential mechanisms may contribute to facilitating cognitive reserve, which can delay late-life cognitive impairment.”
More research is needed to understand whether these possible causes all happen at the same time throughout a person’s life, or if different causes emerge at different stages, the researchers said.
Expert reactions
Dr. Cathryn Devons, M.D., who specializes in geriatric medicine at Phelps Hospital Northwell Health in Sleepy Hollow, New York, was not part of the study but commented on the findings.
Exercise can lower the risk of hypertension, stroke, vascular disease, cholesterol levels and diabetes — “all the things that put you at risk for circulatory problems to the brain,” she told Fox News Digital.
The doctor also noted that exercise is known to help to reduce inflammation, which can protect brain health.
Study limitations
One limitation of the study is that physical activity was based on self-reporting, Hwang told Fox News Digital.
“While we can say from these results that higher levels of overall physical activity are associated with reduced dementia risk, these results cannot translate well to recommendations about specific exercise types,” he said.
Also, the level of physical activity in early adulthood was not linked with all-cause dementia or Alzheimer’s dementia.
“We may have been underpowered to detect associations with early adult life physical activity due to the small number of dementia cases in this age group,” the authors noted.
Devons agreed that while the study may have limitations, it supports the idea of exercise lowering the risk of dementia.
