Mid- and Late-Life Physical Activity May Reduce Dementia Risk By Up to 45%.
Mid- and Late-Life Physical Activity May Reduce Dementia Risk By Up to 45%
A new study provides insight into the relationship between physical activity and brain health, identifying modifiable behavior changes that people can make to delay a potential dementia diagnosis later in life.
Health experts have long touted the benefits of physical activity on both physical and mental health, but what remains less clear is the specific stages in life during which exercise can provide the greatest health-protective effects, particularly on cognition. A new study by School of Public Health and the Chobanian and Avedisian School of Medicine (CAMED) researchers suggests that higher levels of physical activity during midlife and late life may substantially lower a person’s risk for developing Alzheimer’s disease and other types of dementia.
Published in JAMA Network Open, the study found that exercising during midlife from ages 45 to 64 may lower dementia risk by 41 percent, while exercising during late life from ages 65 to 88 could lower this risk by 45 percent. The intensity of physical activity mattered during midlife, with high-intensity exercise yielding the lowest risk of dementia, but the researchers did not observe a difference in risk based on exercise intensity among older adults.
More than 55 million people worldwide are living with dementia, and that number is expected to rise to 78 million by 2030 and 150 million by 2050. There have been notable advances in drug treatments that can help slow the progression of different types of dementia—including Alzheimer’s disease, which is the most common form of the condition—but there is no specific cure to reverse a dementia diagnosis.
That’s why it’s critical to identify the modifiable factors that people can incorporate into their lives to delay this life-altering condition, and these findings build upon previous data that indicate that physical activity is among the most modifiable protective factors for cognition and brain health. The researchers hope this new insight into the benefits of physical activity during mid- and late life stages can help guide relevant decision-making during these life stages.
“We know that increasing levels of physical activity may help to reduce dementia risk, and these results support evidence that the benefits of physical activity on the brain may extend to earlier in life than previously thought,” says study senior and corresponding author Phillip Hwang, assistant professor of epidemiology.
The findings underscore the importance of being physically active through adulthood, says study lead author Francesca Marino, a postdoctoral research associate in the Department of Anatomy & Neurobiology at CAMED. “While all physical activity is likely beneficial, we found that more vigorous physical activity had the strongest links with dementia risk.Taking the time to be physically active now, particularly through higher-intensity activities that raise your heart rate, may help lower your risk of dementia in older age.”
There are several mechanisms through which physical activity can help lower dementia risk, she says. “Physical activity helps improve our brain structure and function and may also directly lower the amount of Alzheimer’s disease neuropathology, such as amyloid-beta and tau. It can also help lower inflammation and improve our cardiovascular health by lowering blood pressure or reducing the risk of diabetes, for example.”
For the study, Hwang and colleagues utilized data from more than 4,300 participants from the Boston University-based Framingham Heart Study Offspring cohort, including 1,526 people in the early adult stage, 1,943 people in midlife, and 885 people in late life. All of the participants were dementia-free at the beginning of the study. The team measured participants’ exercise levels using the physical activity index, a composite score based on the number of hours spent sleeping and in sedentary, slight, moderate, or heavy activities. They grouped participants into five different groups, from lowest to highest physical activity levels.
Notably, the researchers found that the benefits of physical activity differed depending on whether people were carriers of the APOE ε4 allele, which is considered to be the strongest genetic risk factor for Alzheimer’s disease. Among APOE ε4 noncarriers, physical activity was linked to a reduction in dementia risk during both mid- and late-life stages, but for carriers, this association was only observed in late-life.
While substantial research at SPH and beyond suggests that physical activity and other health-protective behavior changes early in life can help delay dementia, the study did not observe increased protective effects against dementia through physical activity in the early adult stage.
This finding was surprising to the researchers, but it doesn’t mean that physical activity during early adult years does not reduce dementia risk, they note.
“Since dementia is not typically diagnosed until older age, it is possible that we did not have enough follow-up information on individuals in the early adult life group,” Marino says. “This may have limited our ability to detect statistical associations.”
More research is needed to better understand how different aspects of physical activity—such as type of activity, duration, intensity, and timing—across the life course relate to the development of dementia, Hwang says.
“Since we only looked at baseline measures of physical activity in this study, we plan to analyze longitudinal measures of physical activity and changes in or patterns of physical activity over time across the adult life course in relation to dementia risk for future projects,” he says.