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I like to think of myself as a moderately active septuagenarian. On a fairly regular basis, for example, I’ll hoist a couple thousand pounds before breakfast and then pedal my bike up the hill to the office a mile away, where I’ll spend the next several hours . . . sitting in front of my computer.

It’s pretty well accepted these days that exercise is good for our gray matter, but I find myself wondering sometimes whether the accumulated hours I spend planted in a chair staring at a screen negates whatever cognitive benefits I may accrue from my well-intentioned workouts. Sitting, as they say, is the new smoking.

So, I was (partially) relieved to learn recently that it may not be sitting itself that raises the risk of a scrambled brain but what we happen to be doing while we’re occupying a chair. That’s what David Raichlen, PhD, a University of Southern California professor of biological sciences and anthropology, and his team of researchers concluded in a study published in the journal Proceedings of the National Academy of Sciences.

“It isn’t the time spent sitting, per se, but the type of sedentary activity performed during leisure time that impacts dementia risk,” Raichlen explains. “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] relatively greater intellectual stimulation that occurs during computer use may counteract the negative effects of sitting.”

Collecting information from U.K. Biobank, Raichlen’s team analyzed self-reported data on sedentary behavior between 2006 and 2010 from more than 145,000 adults 60 years old and older without a dementia diagnosis. Tracking hospital records of the participants 12 years later, they learned that 3,507 of them had developed some form of dementia. After adjusting for demographics and lifestyle characteristics such as exercise, smoking, alcohol use, sleep patterns, and social engagement, researchers concluded that time spent watching TV or using a computer were both “significantly associated with dementia risk” — regardless of an individual’s level of physical activity. But those who spent more time glued to the tube than tapping away on a keyboard were more likely to develop the disease.

“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,” notes study coauthor Gene Alexander, PhD, a professor of psychology at the University of Arizona.

But that’s not what the data revealed, he adds. No matter how much we move our bodies, it doesn’t negate the effects of chair (or couch) time. “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 [while sitting], 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.”

This is somewhat reassuring. While I spend a fair amount of time each day parked in front of my laptop, I tend to resist TV’s siren song now more successfully than I did in my younger days. I long ago lost any interest in Netflix bingeing — there’s always a good book to read — but I must admit that I languished on the couch for a few hours recently while watching a football game involving two teams that I cared nothing about. And I’m not even that interested in football.

Whether any of this makes me more or less susceptible to losing my marbles in the years ahead is anyone’s guess. Raichlen and his crew admit that self-reported data can be unreliable, and they note that the questionnaires participants completed only identified sedentary behavior at a single point in time and that those behaviors may have changed during the follow-up period. “Future studies examining change in sedentary and physical activity behaviors will help us understand the role of long-term sedentary behavior in brain health,” they write.

I’ll be interested to see what subsequent research reveals about this connection, but I’m keener on seeing the Super Bowl in my rearview mirror. That’s when the NBA season really starts to heat up, and I suspect I’ll be tuning in. If you’re going to let TV scramble your gray matter, after all, you might as well enjoy what you’re watching.

Craig Cox
Craig Cox

Craig Cox is an Experience Life deputy editor who explores the joys and challenges of healthy aging.

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