Experts had long believed that exercise could help protect against the development of dementia. However, although they had noted a general pattern of reduced risk, studies on the subject had been small, and often conflicting, with little consensus on what type, frequency, or intensity of exercise might be best.
“There is no really clear prescription that we can provide for physical activity,” said Dr. Joel Salinas, an assistant professor of neurology at New York University Grossman School of Medicine, who specializes in treating people with dementia. .
But three major long-term studies published in recent months have attempted to characterize the types, intensities, and durations of physical activity that confer the most general protection against dementia. These studies, which followed thousands and even hundreds of thousands of people for years, confirm that regular physical activity, in many ways, plays an important role in lowering the risk of developing dementia.
Vigorous exercise seems to be best, but even non-traditional exercise, like doing housework, can offer significant benefit. And surprisingly, it’s just as effective at reducing risk in people with a family history of dementia.
Many forms of exercise can stave off dementia.
In the first studyPublished July 27 in the journal Neurology, the researchers analyzed the health information of 501,376 participants who did not have dementia in a British database called the UK Biobank to establish links between physical activity and the risk of developing the disease.
One of the main advantages of this database was that it had “very rich data on the genetics” of the participants, said Dr. Huan Song, a researcher at Sichuan University West China Hospital, who was one of the authors of the study. study. This included a risk profile of participants based on whether they had genetic variants associated with dementia or had immediate family members with the condition.
At the start of the study, the participants filled out detailed questionnaires about their participation in physical activities, such as playing sports, climbing stairs or walking, and whether they regularly walked or cycled to work. They were also asked about various lifestyle factors, including how often they completed household chores.
One of the main limitations of the previous studies was that “the definition of physical activity is quite weak,” said Dr. Song. “Some use the full amount and some just focus on one mode of activity.” The British questionnaires offered specificity about exactly what activities the participants engaged in on a regular basis.
The participants were followed for 11 years, during which time 5,185 developed dementia. The study found that in participants who engaged in regular, vigorous activities, such as playing sports or exercising, the risk of developing dementia was reduced by 35 percent. Surprisingly, people who reported regularly completing household chores also experienced a significant benefit; they had a 21 percent lower risk.
“Some people sweat quite a bit when they’re doing chores around the house,” said Dr. Sandra Weintraub, a neurologist at Northwestern University Feinberg School of Medicine, who was not involved in this study. “It may be that if you do three hours of housework, you are as good as if you did 30 minutes of aerobic exercise.”
For Dr. Salinas, who recommends that people aim to get 150 minutes of moderate-to-high intensity exercise a week, the results strengthen the idea that regular moderate-to-vigorous exercise can promote brain health. Cultivating this exercise habit “probably has a very profound synergistic effect,” he said. “You get a lot more for your money in terms of helping to promote your own health through physical activity.”
Perhaps most encouraging, the association between physical activity and a lower risk of dementia extended to participants who had a family history of dementia.
“It’s very important to know that if you have a family history of dementia, you can use physical activity to lower your risk,” said Dr. Song.
Start by doing what you like the most.
the second role, published last week in Neurology, compiled 38 studies to see which leisure activities were associated with a lower risk of dementia. In all, the studies followed more than two million dementia-free participants for at least three years, during which time 74,700 developed dementia.
After controlling for age, education, and gender, the researchers found that participants who exercised regularly, defined as participating in activities such as walking, running, swimming, dancing, participating in sports, or working out at the gym, had a 17 percent lower risk of developing dementia compared to those who did not.
This meta-analysis shows that dementia prevention is not limited to one activity, or even one type of activity. Given the diversity of physical activities that participants do, “we recommend people do the exercise they like,” said Le Shi, a researcher at Peking University and one of the study’s authors.
When it comes to reaping the benefits of physical activity, it’s never too early to start. in a third study published this month, researchers followed more than 1,200 children ages 7 to 15 for more than 30 years. Those with higher levels of fitness as children had higher levels of cognitive functioning in midlife, suggesting that establishing a lifelong habit of physical activity could be beneficial for brain health.
Together, these studies suggest that the ways we move our bodies on a daily basis could add up over time. They also solidify the notion that regular, lifelong physical activity, in all its forms, goes a long way toward reducing the risk of dementia, even for people classified as high risk.
“Your brain is part of your body, and it will benefit from anything you do that is good for your overall health,” said Dr. Weintraub.
Rachel Fairbank is a freelance science writer based in Texas.
