Watching TV Is Linked to Cognitive Decline

Sitting in front of a TV too much doesn’t affect only your children. Even in midlife, television can interfere with your brain functioning.

Parents worry about whether letting their children watch TV (or play video games or stay glued to social media) will hurt their grades and mental development.

The clearest danger is that TV time could substitute for physical exercise, in-person socializing, or reading or other hobbies that help children develop.

Research also suggests that adults may lose cognitive functioning if they maintain a TV habit.

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One study was based on surveys of 10,700 adults in the United States between the ages of 45 and 64. In the late 1980s and again in the early 1990s, they reported whether they rarely, sometimes, or often watched television. Nearly 6,500 gave similar answers at both survey points, suggesting that their TV habits were stable.

In the late 1990s and then between 2011 and 2013, that group took tests of their working memory and speed at language tasks.

The researchers concluded that those who said they sometimes or often watched TV over the years had a 7 percent greater decline in their performance on the tests, compared to people who rarely watched TV. The TV-watchers, however, didn’t seem to have a higher risk of dementia. How much they exercised didn’t seem to affect the results either.

To see how watching TV affects the brain, a second study gave just over 1,600 participants brain scans. People usually have better cognitive skills if they have more gray matter, a darker tissue. This study had a scary finding: If the subjects reported watching TV even moderately, a decade later they had less gray matter than people who rarely watched TV.

In a third study, researchers looked at data for about 600 people with an average age of 30 when the study began and 50 at follow-up. Over two decades, they reported every five years about how many hours of TV they watched each day during the previous year. For most of the people, their watching habits didn’t change much.

When they underwent brain scans in midlife, those who reported watching more TV over the study’s 20 years had less gray matter. For every extra hour of watching, they lost about as much gray matter as people normally do during midlife.

Another way of looking at this information: TV doubled their expected cognitive decline (everyone loses function as they age). But, again, being physically active didn’t make a difference.

Is there a risk for dementia?

There is some good news here, however. If you’re worried about dementia, it appears from this research that watching TV won’t increase your chances. It also suggests that being physically active isn’t the only way to keep your gray matter.

Is all TV bad?

Although the research didn’t pin down which sedentary activities were linked to more gray matter, it would make sense that if you experience an activity that is stimulating or challenging it probably helps.

Some TV shows are complex and will keep you mentally stimulated. Having fun or revealing conversations with your friends and family about TV shows is also a big plus: Social connection is as good for you as exercise. Relaxing is important, too.

But if you can cut back on TV in favor of interesting or social hobbies, you might stay a bit sharper in your later years. Reading, writing, doing crossword puzzles, playing board or card games, engaging in group discussions, and playing music all count. In one study, mentally intact people in their 70s and 80s who said they did those activities frequently lowered their chance of impairment by half.

How to protect yourself from mental aging

• Exercise is your best bet to avoid the illnesses of later life, including cognitive decline and dementia. It may be helpful even for people who already have memory problems.
• A diet with plenty of fish, whole grains, and vegetables will help.
• Heavy drinking raises your dementia risk.
• Getting the right amount of sleep is important.
• Stay connected to others.
• Stimulate your mind. A tricky game of cards will keep you alert. It’s not too late, by the way, according to research with Scottish elders. What you do in your 70s can help you in your 80s.

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