Older women were less likely to develop mild cognitive impairment or dementia if they walked more daily and engaged in moderate to vigorous physical activity, according to a new study from the Herbert Wertheim School of Public Health and Longevity Sciences at the University of California, San Diego.
In the online edition of January 25, 2023 Alzheimer’s disease and dementia: Journal of the Alzheimer’s Association, the team reported that among women age 65 and older, each additional 31 minutes of moderate-to-vigorous physical activity per day was associated with a 21 percent reduced risk of developing mild cognitive impairment or dementia. The risk was also 33 percent lower with each additional 1,865 daily steps.
“Given that the onset of dementia begins 20 years or more before symptoms appear, early intervention to delay or prevent cognitive decline and dementia in older adults is critical,” said senior author Andrea LaCroix, PhD, MPH, professor emeritus Herbert Wertheim School of Public Health and Longevity Sciences at the University of California, San Diego.
Although there are several types, dementia is a debilitating neurological disease that can lead to loss of memory, ability to think, solve problems or reason. Mild cognitive impairment is an early stage of memory loss or thinking problems that are not as severe as dementia.
According to the US Department of Health and Human Services, more than 5 million people in this country suffer from dementia. This number is expected to double by 2050.
More women are living with dementia and are at greater risk of developing dementia than men.
“Physical activity has been identified as one of the three most promising ways to reduce the risk of dementia and Alzheimer’s disease. Prevention is important because once dementia is diagnosed, it is very difficult to slow or reverse it. There is no cure,” Lacroix said.
However, because few large studies have examined device measures of movement and sitting in relation to mild cognitive impairment and dementia, most of the published research on the association of physical activity and sedentary behavior with cognitive decline and dementia is based on self-reported measures. said first author Steven Nguyen, PhD, MPH, a graduate student at the Herbert Wertheim School of Public Health.
For this study, researchers sampled data from 1,277 women as part of two complementary studies of the Women’s Health Initiative (WHI) – the WHI Memorial Study (WHIMS) and the Objective Physical Activity and Cardiovascular Health (OPACH) study. The women wore research-grade accelerometers and went about their daily activities for seven days to get accurate measures of physical activity and sitting.
The activity trackers showed that the women took an average of 3,216 steps, 276 minutes of light exercise, 45.5 minutes of moderate to vigorous exercise and 10.5 hours of sitting per day. Examples of light physical activity include housework, gardening, or walking. Moderate to vigorous physical activity may include brisk walking.
The results of the study also showed that more sitting and prolonged sitting was not associated with a higher risk of mild cognitive impairment or dementia.
Taken together, this information has important implications for clinical practice and public health, as there is little published information on the amount and intensity of physical activity needed to reduce the risk of dementia, Nguyen said.
“Older adults can be encouraged to increase at least moderate-intensity exercise and take more steps each day to reduce the risk of mild cognitive impairment and dementia,” Nguyen said.
“The findings regarding the number of steps per day are particularly noteworthy because the number of steps is recorded by a variety of wearable devices that people increasingly wear and can be easily imitated.”
The authors said further research is needed in different populations, including men.
Co-authors include: John Bellettiere, University of California, San Diego; Kathleen M. Hayden and Stephen R. Rapp, Wake Forest University School of Medicine; Chongzhi Di, Fred Hutchinson Cancer Center; Priya Palta, Columbia University Irving Medical Center; Marcia L. Stefanik, Stanford University School of Medicine; Joan E. Manson, Harvard Medical School; and Michael J. Lamont, University at Buffalo – SUNY.
This study was funded in part by the National Institute on Aging (P01 AG052352, 5T32AG058529-03) and the National Heart, Lung, and Blood Institute (R01 HL105065). The Women’s Health Initiative was funded by the National Heart, Lung, and Blood Institute (75N92021D00001, 75N92021D00002, 75N92021D00003, 75N92021D00004, 75N92021D00005).