Sitting is sitting… Except When It’s Not

September 21, 2022

Not all sitting is the same when it comes to brain health, according to a new report.

The study found that older men and women who sit for long periods of time doing passive activities like watching TV were at higher risk of developing dementia years down the road. People who engaged in cognitively stimulating activities like using a computer while sitting, on the other hand, were at lower risk of dementia.

The findings add to growing evidence that keeping the mind active is good for the brain, and that cognitive stimulation may help to lower the risk of Alzheimer’s disease and other forms of dementia. They also suggest that “active” sitting, in which we engage the mind with intellectually challenging activities like card games, reading or doing crossword puzzles, may be better in the long term for brain health than “passive” sitting like watching television.

“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 Dr. David Raichlen of the University of Southern California. “We know from past studies that 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.” The findings were published in the Proceedings of the National Academy of Science.

For this very large study, researchers analyzed health records and lifestyle habits from 146,651 people who were part of the U.K. Biobank, a large database of medical information of people living in Britain. All were over 60 — their average age was about 65 — and none had Alzheimer’s or other serious memory problems at the start of the study.

The researchers tracked their TV and computer habits over a 12-year period. During that time, 3,507 of them had developed Alzheimer’s or other forms of dementia.

The researchers found that watching TV, a mentally passive activity, while sitting increased the likelihood of developing dementia. On the contrary, using a computer while sitting lowered the risk.

The risk of dementia was independent of whether people also engaged in physical activities while they weren’t sitting. Other studies have shown that exercise and other physical activity can lower dementia risk. This study found that even in people who got lots of exercise, spending time watching TV was associated with a higher risk of dementia, while spending time using a computer was tied to a lower dementia risk.

“Although we know that 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 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.”

“What we do while we’re sitting matters,” Dr. Raichlen added. So next time you hit the couch or armchair, think before turning on the TV. Read a book or magazine, play a word game on the computer tablet, or listen to classical music. All may be better for the brain in the long term.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University. 

Source: David A. Raichlen, Yann C. Klimentidis, M. Katherine Sayre, et al: “Leisure-time sedentary behaviors are differentially associated with all-cause dementia regardless of engagement in physical activity.” Proceedings of the National Academy of Sciences, August 22, 2022


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