Sitting has been called “the new smoking” for a while now, the point being that a sedentary lifestyle may be just as harmful to a long and healthy life as a pack-a-day habit. It’s a catchy way to encourage us to move around more often, because everybody except for a few tobacco industry executives agrees that puffing on cigarettes is bad for your health. The latest warnings about the hazards of too much couch time, on the other hand, may be a slightly harder sell — especially for people of a certain age who are already doing all they can to preserve their cognitive function.
The results of a study published last month in JAMA suggest that clocking too many hours each day in a sitting position may increase a senior’s risk of slipping into dementia. If that wasn’t enough to get our attention, researchers added that the deleterious effects of those sedentary hours are not mitigated by getting up and moving around.
This may require some explanation.
A research team led by David Raichlen, PhD, a University of Southern California professor of biological sciences and anthropology, analyzed data from the UK Biobank measuring the movement patterns and health status of nearly 50,000 dementia-free British men and women over 60. The subjects had worn devices that recorded their activity — and nonactivity — over the course of a week, and Raichlen’s team traced their health records for the next seven years to determine how their movement patterns may have affected their cognitive abilities.
What they found was a disturbing link between too much sitting and a dementia diagnosis. Those who sat for 10 hours a day were 8 percent more likely than their less sedentary peers to develop the disease. And those who clocked in with at least 12 hours of nonactivity (not counting sleep) were a whopping 63 percent more likely to struggle with cognitive dysfunction.
“Sitting in the office all day, then in front of the TV and in the car and all the other ways we find to sit, it adds up,” Raichlen tells the Washington Post. “These extreme levels of sedentary behavior are where we see a much higher risk [for dementia].”
Why that might be the case remains a bit of a mystery, but Raichlen believes it may have something to do with a reduced flow of cerebral blood, robbing the brain of the oxygen and fuel it needs to operate at full capacity.
More surprising — or deflating — was the study’s conclusion that no amount of exercise seemed to reduce the risk of dementia among those who sat for 10 hours a day or more. The same was true even for those who rose from their chairs for short breaks during the day. If you stationed your rear end in a chair for that amount of time, even a daily two-hour workout wouldn’t lower your chances of facing cognitive dysfunction down the road.
“It looks like you can’t exercise your way out of the risk,” Raichlen notes.
But, if we’re to believe his results, a moderate reduction in your daily sitting time can make a big difference. The study found that those whose sedentary time peaked at 9.5 hours a day — a mere 30 minutes less than the 10-hour threshold — experienced no increased risk of developing dementia. We are left to imagine why that might be the case.
Before you start obsessing over your daily movement patterns, however, take note that Raichlen’s study only establishes a possible link between sedentary habits and dementia. There’s nothing in his findings that indicate sitting for extended periods causes cognitive dysfunction. That will take additional research, which is probably a good thing as it may take some time for public-health influencers to come up with a catchy slogan. “Sitting is the new . . . slightly mysterious factor that may or may not raise a senior’s risk of developing dementia” doesn’t exactly encourage us to sit up and take notice.
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