UCSD study links physical activity to decreased dementia risk among women

Moderate to vigorous exercise and daily walks can reduce the risk of developing dementia among senior women, according to a study by UC San Diego researchers published Jan. 25.

A team from UCSD’s Herbert Wertheim School of Public Health and Human Longevity Science found that among women 65 or older, each additional 31 minutes per day of moderate to vigorous physical activity was associated with a 21 percent lower risk of developing mild cognitive impairment or dementia. The risk was 33 percent lower with each additional 1,865 daily steps.

“Given that the onset of dementia begins 20 years or more before symptoms show, the early intervention for delaying or preventing cognitive decline and dementia among older adults is essential,” said senior author Andrea LaCroix, a professor at the Wertheim School.

Dementia is a debilitating neurological condition that can cause loss of memory and the ability to think, solve problems or reason. Mild cognitive impairment is an early stage of memory loss or thinking problems that is not as severe as dementia.

According to the U.S. Department of Health and Human Services, dementia affects more than 5 million people in the United States, and the number is expected to double by 2050.

More women live with and are at higher risk of developing dementia than men, the UCSD researchers said in their study, published in the online edition of Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

“Physical activity has been identified as one of the ... most promising ways to reduce risk of dementia and Alzheimer’s disease,” LaCroix said. “Prevention is important because once dementia is diagnosed, it is very difficult to slow or reverse. There is no cure.”

Due to a lack of scholarly studies on the issue, much of the published research on the association of physical activity and dementia is based on self-reported measures, according to the UCSD study’s first author, Steve Nguyen, a postdoctoral scholar at the Wertheim School.

For the study, researchers sampled data from 1,277 women, who wore research-grade accelerometers and went about their daily activities for up to seven days to obtain measurements of physical activity and sitting.

The activity trackers showed the women averaged 3,216 steps, 276 minutes in light physical activities, 45½ minutes of moderate to vigorous physical activity and 10½ hours of sitting per day. Examples of light physical activity could include housework, gardening or walking. Moderate to vigorous activity could include brisk walking.

“Older adults can be encouraged to increase movement of at least moderate intensity and take more steps each day for a lower risk of mild cognitive impairment and dementia,” Nguyen said. “The findings for steps per day are particularly noteworthy because steps are recorded by a variety of wearable devices increasingly worn by individuals and could be readily adopted.”

The authors said further research is needed among large, diverse populations that include men. ◆