Physical activity helps prevent dementia, cognitive impairment in women

Walking daily and performing moderate-to-vigorous physical activity can help lower the risk of mild cognitive impairment (MCI) or dementia in ageing women, as shown in a study.

Among women at least 65 years of age, the risk of developing MCI or dementia decreases by 33 percent for every additional 1,865 daily steps (hazard ratio [HR], 0.67, 95 percent confidence interval [CI], 0.54–0.82) and by 21 percent for every additional 31 minutes of moderate-to-vigorous physical activity per day (HR, 0.79, 95 percent CI, 0.67–0.94). [Alzheimers Dement 2023;doi:10.1002/alz.12908]

Women in the highest quartiles of moderate-to-vigorous physical activity had a lower risk of MCI or dementia as compared with those in the lowest quartile (quartile 4: HR, 0.69, 95 percent CI, 0.45–1.06; quartile 3: HR, 0.79, 95 percent CI, 0.53–1.17; quartile 2: 1.28, 95 percent CI, 0.90–1.81; p=0.01 for trend). The same was true for the quartiles of daily steps (quartile 4: HR, 0.38, 95 percent CI, 0.23–0.61; quartile 3: HR, 0.64, 95 percent CI, 0.43–0.94; quartile 2: 0.73, 95 percent CI, 0.51–1.03; p<0.001 for trend).

Meanwhile, increased sitting time and prolonged sitting did not contribute to an increased risk of MCI or dementia.

This study is unique in that it examined accelerometer-measured physical activity, including steps, and sitting with incident Alzheimer disease and related dementias, according to first study author Dr Steven Nguyen from the University of California San Diego in San Diego, California, US.

Few large studies examined device measures of movement and sitting in relation to mild cognitive impairment and dementia, and much of the published research on this subject was based on self-reported measures, Nguyen added.

For their study, Nguyen and colleagues looked at 1,277 women (mean age, 82 years) who participated in Women's Health Initiative (WHI) ancillary studies. All women wore research-grade accelerometers for up to 7 days to provide accurate measures of physical activity and sitting time.

The accelerometer data showed that the women had a daily average of 3,216 steps, 276 minutes of light physical activity, 45.5 minutes of moderate-to-vigorous physical activity, and 10.5 hours of sitting time. Light physical activity included housework, gardening, or walking, whereas moderate-to-vigorous physical activity involved brisk walking, among others.

A total of 267 women were diagnosed with MCI or probable dementia over a median follow-up of 4.2 years.

“Physical activity has been identified as one of the three most promising ways to reduce risk of dementia and Alzheimer's disease. Prevention is important because once dementia is diagnosed, it is very difficult to slow or reverse. There is no cure,” senior author Dr Andrea LaCroix from the University of California San Diego pointed out.

“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,” LaCroix added.

In light of these findings, the authors emphasized the importance of promoting increased movement and at least moderate intensity physical activity among older adults to lower their risk of MCI and dementia.

“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,” Nguyen said.

The authors called for more studies to validate their findings in large diverse populations that include men.