Adults age 60 and older who spend long periods of time watching TV or engaging in other inactive, sedentary behaviors may have an increased risk of developing dementia, according to a new study by researchers at USC and the University of Arizona.
Their study also showed that the risk was lower for those who were active while sitting, such as when they read or used a computer.
The study is published today in the journal Proceedings of the National Academy of Sciences. It also revealed that the association between sedentary behavior and dementia risk persisted even in physically active participants.
“It’s not time spent sitting, but sedentary activity during leisure time, that affects the risk of dementia,” said study author David Raichlen, professor of biological sciences and anthropology in the USC Dornsife College of Letters, Arts. and science.
“We know from previous studies that watching TV reduces muscle activity and energy use compared to commuting or reading,” he said. “And while research has shown that long periods of uninterrupted sitting are linked to reduced blood flow to the brain, the relatively greater intellectual stimulation that occurs during computer use may counteract the negative effects of sitting.”
The researchers used self-reported data from the UK Biobank, a large-scale biomedical database of more than 500,000 participants across the United Kingdom, to investigate potential links between sedentary leisure activity and dementia in older adults.
More than 145,000 participants age 60 and older — not all of whom were diagnosed with dementia at the start of the project — used touchscreen questionnaires to self-report information about their level of sedentary behavior during the 2006-2010 baseline survey period. .
After an average of about 12 years of follow-up, the researchers used in-hospital patient records to determine the dementia diagnosis. 3 thousand 507 positive cases have been found among them.
Next, the team adjusted for certain demographics (eg, age, gender, race/ethnicity, type of employment) and lifestyle characteristics (eg, exercise, smoking and alcohol use, sleep duration and social interaction) that may affect brain health. .
Effects of physical activity, mental activity on risk
Even after the scientists accounted for physical activity levels, the results remained the same. Even among highly physically active people, time spent watching TV was associated with an increased risk of dementia, and leisure time spent using a computer was associated with a reduced risk of developing dementia.
“We know that physical activity is good for our brain health, but many of us think that if we are too physically active during the day, we can counteract the negative effects of time spent sitting,” said study author Jean Alexander, professor. Psychology and the Evelyn F. McKnight Brain Institute at the University of Arizona.
“Our findings suggest that the effects of leisure time on the brain are independent of how physically active we are,” Alexander said, adding that “being mentally active, like using a computer, may be a key way to help cope. TV Increased risk of dementia associated with passive sedentary behaviors such as looking.”
Knowing how sedentary activities affect human health may lead to some improvements.
“It’s what we do while we’re sitting that matters,” Raichlen added. “This knowledge is important when it comes to designing public health interventions aimed at reducing the risk of neurodegenerative disease from sedentary activities through positive behavior change.”
This study was supported by grants from the National Institutes of Health (P30AG072980, P30AG019610, R56AG067200, R01AG049464, R01AG72445), the State of Arizona and the Arizona Department of Health Services, and the McKnight Brain Research Foundation.