Boston University–Led Research Finds Mid- or Late-Life Exercise May Cut Risk of Dementia
Epidemiologist Phillip Hwang says high levels of physical activity could lower dementia risk by up to 45 percent
Dementia cases are expected to surge over the next 25 years; mid- and late-life exercise may help reduce the risk of a diagnosis, a BU-led study suggests. Photo via iStock/AscentXmedia
Boston University–Led Research Finds Mid- or Late-Life Exercise May Cut Risk of Dementia
Epidemiologist Phillip Hwang says high levels of physical activity could lower dementia risk by up to 45 percent
With the number of dementia cases worldwide expected to triple over the next quarter century, new Boston University research highlights a potential way to thwart the disease: exercise. And the adage, “It’s never too late to start,” may apply. That’s the hopeful possibility raised in a study led by Phillip Hwang, a BU School of Public Health assistant professor of epidemiology.
The research, published in the journal JAMA Network Open, involved more than 1,500 participants in the BU-led Framingham Heart Study, an eight decade–old research initiative. The researchers found that a high level of physical activity in mid- or late-life was associated with a lower risk of dementia of 45 and 41 percent, respectively. (The research defined mid-life as between the ages of 45 and 64, with late life categorized as ages 65 to 88.)
Previous studies by others corroborate the link between exercise and cognitive health. For example, 2022 research reported that people who walked just 3,800 steps per day lowered their risk of dementia by 25 percent. Another study found that biking rather than using a car or mass transit was associated with a reduced risk of dementia and Alzheimer’s of 19 and 22 percent, respectively.
The Brink asked Hwang, who is also an investigator with the Framingham Heart Study, about the implications of his research.
Q&A
with Phillip Hwang
The Brink: What type of exercise did your later-in-life subjects do—cardio, strength training, both? And how vigorous must the exercise be to reduce dementia risk?
Hwang: From this study at least, we cannot say what type of exercise, or how much exercise specifically, one needs to do, since the measure of physical activity used in the study, PAI [Physical Activity Index], reflects overall daily physical activity. It is a composite measure based on the number of hours a person spends sleeping, in sedentary behavior, and doing light, moderate, and heavy activities in a day. This is a limitation of using this particular measure of physical activity, which does not provide much clinical interpretability, only relative comparisons between different physical activity levels. However, finding ways to be more active and moving around is important, especially if more time is typically spent being sedentary.
The Brink: What was the study’s methodology? Did you review decades of exercise and dementia records of the participants?
This was a secondary data analysis, where all the information was already collected and available. I did not have to wait or follow up with participants for information on physical activity and/or dementia diagnosis. The main part of the project consisted of analyzing the data.
The Brink: Do you know how many of your mid- and late-life study subjects had been exercising all their lives, as opposed to taking up exercise later in life?
We did not evaluate information on physical activity collected earlier in life. This is something we plan to pursue as a future project to examine physical activity patterns and changes over time across the adult life course.
The Brink: Why does exercise reduce the risk of dementia? What’s the physiological mechanism involved?
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.
Physical activity may also directly impact neurodegenerative disease pathology, such as beta-amyloid in the case of Alzheimer’s disease. [Beta-amyloid is a protein that causes sticky plaques, which can kill brain cells.] These potential mechanisms may contribute to facilitating cognitive reserve, which can delay late-life cognitive impairment. More research is needed to understand whether these potential mechanisms act together at the same times during the life course, or if different mechanisms exist independently during middle or late-life.
The study was funded primarily by the National Heart, Lung, and Blood Institute of the National Institutes of Health.
