Watching Just This Much TV Weekly Raises Your Dementia Risk, Study Says
Researchers have found that longer viewing leads to a higher chance of the condition.
Sitting down in front of the TV to catch up with your favorite shows can be the perfect way to unwind after a long day. Unfortunately, while an episode here and there might be OK, we've also been told from a young age that it's not the healthiest of habits to overindulge in binge-watching sessions. But according to research, there's also a health risk for older adults who can raise their risk of dementia by taking in too much TV weekly even later in life. Read on to see how much viewing can be potentially bad for your brain health.
Watching 24.5 hours of TV a week can increase your risk of developing dementia.
A study published in February 2019 in the journal Scientific Reports set out to better understand how television viewing habits could affect cognition in people aged 50 and older, with the study's authors arguing that most research on the topic tends to focus on children and young adults. To test their theory, the team gathered 3,662 participants with an average age of 67 who all resided in England and had not been diagnosed with dementia. The group then reported how much TV they watched each day and had their cognition tested. Researchers observed how well each could remember a list of 10 common words and could come up with as many words as they could from a specific category in a minute—first in 2008 or 2009, and then again in 2014 or 2015.
Results of the study show that participants who watched more than 24.5 hours of TV per week—or 3.5 hours a day—saw an average of an eight to 10 percent decrease in verbal memory, the BBC reported. Participants who watched less than 3.5 hours a day saw a four to five percent decrease by comparison.
Watching too much TV can keep the brain from more stimulating activities such as reading or exercise.
The team concluded that watching television itself may not be damaging to the brain. Instead, a high amount of hours spent in front of the TV creates long periods of sedentary behavior that passively distract the brain and prevent people from engaging in other stimulating activities, such as exercise or reading.
"Research suggests that television is a bit of unusual activity for the brain because you've got lots of bright and fast-moving images so your brain is very alert, but at the same time it is quite a passive activity to engage in, and this has been shown to lead to a less-focused brain," Daisy Fancourt, PhD, one of the study's authors from University College London (UCL), said in a statement. "Overall, this suggests that adults over the age of 50 should try and ensure television viewing is balanced with other contrasting activities."
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Experts said more information on what participants were watching may be needed to clarify the results.
The authors also pointed out shortcomings in their research, including that the reported viewing hours didn't include which types of programs were being watched. "Older people tend to like watching more soap operas, which can be stressful because they identify closely with the characters," Andrew Steptoe, PhD, one of the study's authors from UCL, told the BBC. "This may create cognitive stress which could contribute to memory decline."
Outside experts also offered differing opinions on the findings, with some pointing out that more context may also be needed behind viewing numbers. "There is still a lot we don't know, such as whether memory reductions are affected by what we watch, whether we watch alone or whether you interact with the TV…We also don't know whether changing behavior would improve memory," Dame Til Wykes, PhD, a professor of clinical psychology and rehabilitation from King's College London, told the BBC. "Although this result will cause us to think carefully about screen time, a lot more research is needed before we panic and closely measure TV time like a step counter."
Still, others said the findings reinforce the idea that too much viewing could be bad for cognitive health. "While TV may not rot the brain as traditional wisdom may suggest, even moderate watching is associated with some very real changes among viewers aged over 50," Bob Patton, PhD, a lecturer in clinical psychology from the University of Surrey in the U.K., said of the study.
Other studies have found a connection between dementia and increased TV watching.
Other recent studies have established a connection between watching more TV and an increased risk of dementia. Research presented at the American Heart Association's Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Conference in May 2021 considered data from three studies. Results showed that participants who reported watching more television during mid-life—defined as between the ages of 40 and 70—saw a greater degree of cognitive decline and a reduction in the volume of gray matter in their brains later in life compared to those who reported watching less TV, Live Science reports.
"In our findings, television viewing remained associated with cognitive function and gray matter volume after accounting for physical activity, suggesting that this sedentary behavior may impart a unique risk with respect to brain and cognitive health," Ryan Dougherty, PhD, lead author of one of the studies and a postdoctoral fellow in the Department of Epidemiology at the Johns Hopkins Bloomberg School of Public Health, said in a statement. He added that since that specific processes begin in middle age that can lead to the onset of dementia, it was "a period [where] modifiable behaviors, such as excessive television viewing, can be targeted and reduced to promote healthy brain aging."
However, Dougherty also argued that simply sitting still didn't account for watching TV being a particularly harmful activity. "In the context of cognitive and brain health, not all sedentary behaviors are equal; non-stimulating sedentary activities such as television viewing are linked to greater risk of developing cognitive impairment, whereas cognitively stimulating sedentary activities [such as reading, computer and board games] are associated with maintained cognition and reduced likelihood of dementia," he said in the statement.