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 led by the Herbert Wertheim School of Public Health and Human Longevity Science at the University of California San Diego.
In the January 25, 2023 online edition of Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association, the team reported that in women aged 65 or older, every 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 also 33 percent lower for every additional 1,865 daily steps.
“Since the onset of dementia begins 20 years or more before symptoms appear, early intervention for slowing or preventing cognitive decline and dementia in older adults is essential,” says senior author Andrea LaCroix, Ph.D., MPH, Distinguished Professor at the Herbert Wertheim School of Public Health and Human Longevity Science at UC San Diego.
While there are several forms, dementia is a debilitating neurological condition that can lead to loss of memory, the ability to think, problem solve 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 this country. That number is expected to double by 2050.
More women are living with and at a higher 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 it down or reverse it. is not a cure,” said LaCroix.
However, because few large studies have examined device measures of exercise and sitting in relation to mild cognitive impairment and dementia, much of the published research on the associations of physical activity and sedentary behavior with cognitive decline and dementia is based on self-reported measures, said first author, Steven Nguyen, Ph.D., MPH, a postdoctoral researcher at the Herbert Wertheim School of Public Health.
For this study, the researchers collected data from 1,277 women as part of two supporting studies of the Women’s Health Initiative (WHI): the WHI Memory Study (WHIMS) and the Objective Physical Activity and Cardiovascular Health (OPACH) study. The women wore research-grade accelerometers and performed their daily activities for up to seven days to obtain accurate measurements of physical activity and sitting.
The activity trackers showed that the women took an 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 per day. Examples of light physical activity include housework, gardening, or walking. Moderate to vigorous physical activity can include brisk walking.
The study findings also showed that more sitting and prolonged sitting were not associated with a higher risk of mild cognitive impairment or dementia.
Together, this information is of clinical and public health importance, as there is little published information about the amount and intensity of physical activity necessary for a lower risk of dementia, Nguyen said.
“Older adults may be encouraged to increase exercise 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 that are increasingly worn by individuals and are easily adopted.”
The authors said further research is needed among large diverse populations, including men.
Co-authors include: John Bellettiere, UC 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. Stefanick, Stanford University School of Medicine; JoAnn E. Manson, Harvard Medical School; and Michael J. LaMonte, University at Buffalo — SUNY.
This research 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).