Over 45 and have never exercised? You still have time
What's the story
Scientists have long emphasized the brain-protective benefits of exercising early in life, but new research shows that starting later still makes a difference. According to a study published on November 19 in the journal JAMA Network Open, people who maintained the highest levels of physical activity in midlife and late life had a 41% and 45% lower risk of developing dementia, respectively. The study defined midlife as ages 45 to 64, and late life as ages 65 to 88.
Paradigm shift
Shift in perspective on exercise and brain health
Dr. Sanjula Singh, an instructor in neurology at Harvard Medical School, said that the findings of the study have prompted a shift in the conversation from "exercise is good for the brain" to "there may be key windows when exercise matters most for brain health." She highlighted that midlife is a time when risks for certain health issues increase, making exercise even more important.
Research goals
Study's aim and limitations
Dr. Phillip Hwang, lead author and assistant professor at Boston University School of Public Health, explained that 57 million people worldwide are living with dementia, and this number is expected to triple by 2050. The study aimed to see whether physical activity's effect on dementia risk changes across adulthood. He noted, however, that it could not determine exact exercise amounts because it measured a mix of sleep, sedentary time, and different activity levels.
Supporting evidence
Other studies support findings on exercise and dementia risk
Other studies have also supported Hwang's findings with more specific guidance. A 2022 study found that people who walked just 3,800 steps per day lowered their risk of dementia by 25%. Riding a bike instead of using a car, bus or train for transport has been linked to a 19% lower risk of dementia and a 22% reduced risk of Alzheimer's disease.
Activity guidelines
WHO's recommendations on physical activity for adults
The World Health Organization (WHO) recommends adults to engage in at least 150-300 minutes of moderate-intensity aerobic activity or 75-150 minutes of vigorous-intensity aerobic activity each week. This could include activities like brisk walking for 150 minutes, vigorous running or cycling for 75 minutes, and strength training a couple of times per week.
Participant details
Study's participant demographics and limitations
The new study's findings are based on 1,526 early adult life participants (ages 26-44), nearly 2,000 middle-age adults, and nearly 900 older adults. Physical activity levels in early adult life weren't linked to dementia risk either way. Even for older adults with the strongest genetic risk factor for Alzheimer's disease—the APOE e4 gene—high physical activity was still associated with a 66% lower risk of dementia.