Even light physical activity may help prevent dementia

You don't have to be a marathon runner to help keep your brain healthy. Regular walks through your neighbor-hood or trips to the grocery store may still reduce your risk of dementia a bit, according to a study published online Dec. 16, 2021, by JAMA Network Open.

"We already knew from many studies that moderate- and vigorous-intensity physical activity was associated with a reduced risk for developing dementia," says Dr. Andrew Budson, Chief of Cognitive and Behavioral Neurology at the Harvard-affiliated VA Boston Healthcare System. "What's new in this study is that even light-­intensity physical activity was associated with a reduced risk."

About the study

This study was very well designed, says Dr. Budson. Not only was the sample size large — more than 62,000 people — but the researchers used careful criteria to determine whether people truly had dementia, and that they hadn't changed their exercise habits in response to a dementia diagnosis.

Study participants were age 65 or older and dementia-free at the start of the trial. All had health check-up data in a Korean national insurance database between January 2009 and December 2012.

Based on their self-reported activity, researchers divided them into four categories based on how close each person came to meeting the recommended activity range of 150 to 300 minutes per week of moderate-intensity physical activity or 75 to 150 minutes of vigorous-intensity physical activity.

The categories were

• inactive (didn't do any physical activity)
• insufficiently active (did less than the recommended activity range)
• active (met the recommended activity range)
• highly active (exceeded the recommended activity range).

The researchers then followed the participants for about three-and-a-half years. During that time, 3,757 of them were diagnosed with dementia.

Exercise appeared to be linked with individual risk. The more exercise someone got, the less likely that person was to develop dementia. But it wasn't only the active or highly active participants who saw a reduction in dementia risk. Even people in the insufficiently active category still had a lower risk for dementia than the people who were inactive.

Applying the findings

The findings are good news if you feel like you aren't getting as much exercise as you should.

"There are many people who are either unable to or do not wish to perform moderate- or vigorous-intensity physical activity on a regular basis," says Dr. Budson. "This study shows that if these individuals can perform light-intensity physical activity, they can still reduce their risk of dementia. Their risk reduction is not as great as those who exercise more, but it is certainly a risk reduction relative to those who are inactive."

The findings should also motivate you to squeeze more activity into your day whenever you can, he says.

"Even small decisions that we make in our daily life can affect our future risk for dementia," says Dr. Budson.

Take a short walk around the block each day, or try to do your own shopping or housework. Also aim to add more steps into your everyday activities. For example, make two trips with the laundry, instead of one.

"This study suggests that whether you decide to walk up or down the stairs, versus taking the elevator, makes a difference," he says.

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