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Science says too much TV now could literally shrink your brain later, so chill with the Netflix

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May 27, 2021, 9:55 AM EDT

Your parents probably used to tell you to switch the boob tube off already because all those Saturday morning cartoons would fry your brain. Turns out they were kind of right.

TV will not literally make your brain sizzle and steam come out of your ears—but don’t pick up the remote just yet. Studies by scientists Kelley Pettee Gabriel of the University of Alabama Birmingham, Priya Palta of Columbia Unviersity and Ryan Dougherty of Johns Hopkins University found it can end up shrinking the amount of gray matter you have years from now. Watching TV is seen as a non-stimulating sedentary behavior. Netflix bingeing might have gotten you through quarantine, but it may also lead to dementia and other degenerative brain diseases.

“We have only recently discovered that sedentary behavior may have different associations with health and disease than low or inadequate physical activity,” Gabriel told SYFY WIRE in an interview. “Now that we understand more, we are improving the ways we measure these behaviors. New methods to measure sedentary behaviors include wearable devices and more comprehensive questionnaires."

These preliminary studies are venturing into a largely unexplored frontier. While the positive effects of exercise on the brain have been much more thoroughly studied, what being sedentary does to cognitive function was usually an area left neglected. There are many other variables that will be considered as the research continues, such as whether some types of programs are more stimulating than others of if exercising while you watch TV has the same negative effects as kicking back to binge the whole second season of The Witcher.

Gabriel’s study, which was recently presented at the American Heart Association’s virtual Epidemiology, Lifestyle & Cardiometabolic Health Conference along with the two others, plugged in to how rates of TV watching in midlife were related to the amount of gray matter the subjects (average age 76) retained later in life. This involved self-reporting from the subjects on how often they watched TV in midlife, though they were not asked to specify any amount of time. The answer choices were seldom/never, sometimes or often/very often.

MRI of a brain with a lesion in the left thalamus (shown in white). Credit: BSIP/UIG/Getty Images

 

“TV viewing is only one type of sedentary behavior,” said Gabriel. “To examine this further, studies need to include wearable devices that measure total accumulated time spent sedentary, along with more comprehensive report-based measures that include measurement of time spent in other types of common sedentary behaviors.”

It is possible that other sedentary activities that require more brain power, like reading, may not have such a negative effect on the brain. That will have to go unknown for now. For Gabriel’s study, subjects underwent MRI scans that would show the amount of gray matter in the brain as well as other structural brain markers that could indicate the risk or onset of disease. You really don’t want to lose gray matter is heavily involved in vision, hearing, muscle control, decision-making and other functions.

Gray matter can be superficial, which is the stuff also known as the cerebral cortex, often seen splattered everywhere in zombie or slasher movies (another TV reference). Deep gray matter is made of lumps of neurons with extended nerve fibers. The team also looked into structural markers such as cerebrovascular lesions, white matter, which is also found in deeper brain tissue, and brain volume. Gabriel found the brains of those who answered that they watched TV sometimes, often or very often decades earlier were found to have more atrophy or deterioration, which was given away by their lower volumes of deep gray matter. Yikes.

“We still do not know how much physical activity and what intensity level is needed to optimize brain health,” she said. “The amount or intensity of physical activity might even vary by individual characteristics like age. We also need better measures of sedentary behavior. So, it’s too soon to tell, but other studies have shown the benefits of physical activity; despite time spent sedentary.”

For now, if you really want to know what monster Geralt of Rivia runs into next, get the Netflix app, go to the gym, get on the treadmill and watch on your smartphone while you feel the burn.