What older adults do while they sit affects dementia risk, study indicates
Adults aged 60 and older who sit for long periods watching TV or other such passive, sedentary behaviors may be at increased risk of developing dementia, according to a new study by researchers at the USC Dornsife College of Letters, Arts and Sciences and the University of Arizona.
The study also showed that the risk is lower for those who are active while sitting, such as when they read or use computers.
Published Aug. 22 in the Proceedings of the National Academy of Sciences, the study also revealed that the link between sedentary behavior and dementia risk persisted even among participants who were physically active.
“It isn’t the time spent sitting, per se, but the type of sedentary activity performed during leisure time that impacts dementia risk,” said study author David Raichlen, professor of biological sciences and anthropology at USC Dornsife.
“We know from past studies that watching TV involves low levels of muscle activity and energy use compared with using a computer or reading,” he said. “And while research has shown that uninterrupted sitting for long periods is linked with reduced blood flow in the brain, the relatively greater intellectual stimulation that occurs during computer use may counteract the negative effects of sitting.”
Physical activity and mental activity affect dementia risk
Even for individuals who are highly active physically, time spent watching TV was associated with increased risk of dementia, and leisure time spent using a computer was associated with a reduced risk of developing dementia.
“Our findings suggest that the brain impacts of sitting during our leisure activities are really separate from how physically active we are and that being more mentally active, like when using computers, may be a key way to help counter the increased risk of dementia related to more passive sedentary behaviors, like watching TV,” said study author Gene Alexander, professor of psychology at the University of Arizona.
Knowing how sedentary activities impact human health could lead to some improvements.
“What we do while we’re sitting matters,” Raichlen added. “This knowledge is critical when it comes to designing targeted public health interventions aimed at reducing the risk of neurodegenerative disease from sedentary activities through positive behavior change.”
About the study
In addition to Raichlen and Alexander, authors of the study include, from USC Dornsife, PhD student Katherine Sayre, Mark Lai, assistant professor of psychology, and Rand Wilcox, professor of psychology; and Yann C. Klimentidis and Pradyumna K. Bharadwaj of the University of Arizona.
The study was supported by grants from the National Institutes of Health (P30AG072980, P30AG019610, R56AG067200, R01AG049464, R01AG72445), the state of Arizona and Arizona Department of Health Services, and the McKnight Brain Research Foundation.