Tue, 23 August 2022 at 1:16 pm
People over 60 who spend a lot of time sitting down watching television are at increased risk of developing dementia, according to new research – but the risk is reduced if they do a “less passive” activity while seated.
Using a computer or reading, which involves “relatively greater intellectual stimulation”, can mitigate the negative effects of sitting, the study revealed.
The study, conducted by researchers at the University of Southern California (USC) and University of Arizona, showed the link between sedentary behaviour and dementia persisted – even if participants were physically active.
However, the type of activity while sitting is key when assessing the potential effect on the brain.
“What we do while we’re sitting matters,” said study author David Raichlen, professor of biological sciences and anthropology at the USC Dornsife College of Letters, Arts and Sciences.
“It isn’t the time sitting, per se, but the type of sedentary activity performed while sitting that impacts dementia risk,” he said.
“We know from past studies watching TV involves low levels of muscle activity and energy use compared with using a computer or reading.
“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.”
Researchers used self-reported data from the UK Biobank, a medical database of more than 500,000 people, in a bid to establish links between sedentary activity and dementia in older people.
More than 145,000 participants aged 60 or older were asked to complete touchscreen questionnaires about their behaviour between 2006 and 2010.
None of them had a diagnosis at the start of the study.
But after a follow-up on average 12 years later, more than 3,500 positive cases were found.
The researchers took into account demographics including sex, race and ethnicity and jobs, together with lifestyle choices related to exercise, smoking, alcohol consumption, socialising and sleeping.
And the results were unchanged in people who were highly physically active.
“Although we know physical activity is good for our brain health, many of us think that if we are just more physically active during the day, we can counter the negative effects of time spent sitting,” said study author, Gene Alexander, professor of psychology and the Evelyn F. McKnight Brain Institute at the University of Arizona.
“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 behaviours, like watching TV.”