- Watching large amounts of TV may shrink your brain over time, according to new research.
- This brain shrinkage is linked to cognitive issues down the road.
- There are a few ways to reduce the health risks associated with TV viewership, according to doctors.
There’s nothing like catching up with your favorite show after a long, stressful day. But new research suggests that regularly watching a lot of TV could have a big effect on your brain—and not in a positive way.
The study, published in Alzheimer’s and Dementia: Journal of the Alzheimer’s Association, analyzed data from more than 1,700 adults with an average age of 53. (The participants were part of the Atherosclerosis Risk in Communities Study, a long-term U.S. population study that examines cardiovascular and brain health.) The researchers asked participants how often they watched TV in their free time, along with how much time they spent sitting at work. About 20 years later, the participants were given MRI brain scans.
Ultimately, the researchers found that those who watched TV “very often” in their free time had smaller volumes in brain areas that are connected with early signs of Alzheimer’s disease. Those with high TV viewership also had greater amounts of white matter hyperintensities, which have been linked to cognitive decline and dementia. Additionally, they had smaller frontal and occipital lobes. (The frontal lobes play a role in planning, decision-making, and other executive functions; the occipital lobes are responsible for visual processing.)
“Sedentary behavior has become a major part of modern life, but not all sedentary activities are the same,” says Natan Feter, Ph.D., lead study author and postdoctoral research associate at the University of Southern California. “Spending an hour reading a book is very different from spending an hour passively watching television.”
So, should you change your TV viewing habits? Here’s what experts want you to keep in mind.
Meet the experts: Soma Sengupta, M.D., Ph.D., chair of neurology and neurologist-in-chief at Tufts Medical Center; Anna Hohler, M.D., director of neurology for Northwell in Westchester, chair of neurology at Northern Westchester Hospital, and chief of neurology at Phelps Hospital; Kang Hsu, M.D., internal medicine physician; Randy D’Amico, M.D., neurosurgeon at Northwell’s Lenox Hill Hospital; Natan Feter, Ph.D., lead study author and postdoctoral research associate at University of Southern California.
What’s behind the link?
It’s important to call out a few caveats first. One is that the study was observational, meaning it doesn’t prove that watching a lot of TV causes shrinkage in some areas of the brain. Instead, it simply found a link between the two. Also, the researchers didn’t take MRI scans of participants’ brains before the 20-year follow-up, making it hard to tell if the shrinkage and hyperintensities had developed during that 20-year period or already existed at the beginning of the study.
Still, there does seem to be something to this correlation, particularly because it doesn’t seem the effects can be explained away as the result of sedentary behavior alone. The researchers also found that those who spent a large portion of their workday sitting had larger frontal and occipital lobes and lower white matter hyperintensity volumes—essentially the opposite of what the researchers discovered in people who watched a lot of TV. This suggests that people who spent their workdays sitting had better brain health than those who spent time sitting and watching TV. The researchers theorized that this could be because people who sit while they work are often problem-solving and being intellectually stimulated, while people who watch TV may simply be taking it in.
But doctors say there are a few things about TV that may not be so great for brain health. One is that TV is a passive activity. “Unlike reading, learning a new skill, working, or even using a computer for problem-solving, television often requires little active mental engagement,” says Soma Sengupta, M.D., Ph.D., chair of neurology and neurologist-in-chief at Tufts Medical Center. “Over many years, less cognitive stimulation could contribute to less ‘exercise’ for brain networks involved in planning, memory, and attention.”
Watching TV may also replace healthier activities, says Anna Hohler, M.D., director of neurology for Northwell in Westchester, chair of neurology at Northern Westchester Hospital in Mount Kisco, New York, and chief of neurology at Phelps Hospital in Sleepy Hollow, New York. “Over many years, individuals who spend a large amount of time watching television may be replacing activities that help maintain and strengthen neural networks involved in memory, attention, executive function, and problem-solving,” she says.
Add Prevention as a preferred source in your Google search results.
Use your Google account to add this to your settings.
Heavy TV viewing is also associated with other lifestyle behaviors that may impact brain health, like long periods of sitting, snacking, poorer sleep, or lower levels of physical activity, Feter says. “Although we accounted for many of these factors in our analyses, they may still contribute to the observed associations,” he says.
Dr. Sengupta says it’s also possible that people who have subtle changes in their brain health may choose more passive activities like watching TV years before symptoms develop.
But the study doesn’t actually prove that TV causes brain shrinkage, says Randy D’Amico, M.D., neurosurgeon at Northwell’s Lenox Hill Hospital. “It’s more of a statement that our sedentary time matters,” he says.
Are there ways to make watching TV healthier?
The study didn’t differentiate between various types of TV programming. However, Dr. Sengupta says that some shows may be more “mentally demanding” than others. She cites these as options as potentially more “cognitively engaging”:
- Documentaries that teach new information
- Complex dramas or mysteries that require you to follow different storylines
- Educational or science shows
“If TV is watched in ways that force you to think, predict, remember key plot elements, or discuss ideas, it likely behaves more like cognitively active ‘sitting’ than passive viewing,” says Kang Hsu, M.D., an internal medicine physician in Washington.
One more thing to consider, per Dr. Hohler: “Adding closed captions stimulates the brain in a more active way, as it includes a reading component.”
Still, Dr. Sengupta stresses that there isn’t strong evidence to suggest that choosing “smarter” TV shows counteracts the changes highlighted in the study. “The broader issue appears to be how mentally active you are while spending long periods sitting,” she says.
Dr. Hohler also suggests that you avoid long TV viewing sessions. “Taking regular breaks, staying physically active throughout the day, and ensuring television doesn’t replace sleep, exercise, social interaction, or mentally-stimulating activities are all important strategies for maintaining long-term cognitive health,” she says. She also suggests doing “light physical activity” while you watch TV, like walking on a treadmill, using a stationary bike, stretching, or doing simple exercises. These “can help counteract the effects of prolonged sitting and may support both cardiovascular and brain health,” Dr. Hohler says.
There are other ways to make watching TV more stimulating, Dr. Hohler adds. “Watching with friends or family and discussing the content can add an important social and cognitive component,” she says.
The bottom line
Dr. D’Amico stresses that TV isn’t necessarily bad for your brain as a whole. “It’s just as important to just think about what television is replacing,” he says. “If hours of passive screen time come at the expense of exercise, learning, social connection, or sleep, that’s where I become concerned. Brain health is about maintaining an active, engaged lifestyle.”
Read the full article here