A new study spanning more than two decades found that adults who reported watching television “very often” in midlife later showed smaller brain volumes in regions tied to memory and decision-making, along with more signs of small-vessel brain damage linked to dementia.
“For years we’ve focused on how much people sit. Our findings suggest we should also pay attention to what they’re doing while they’re sitting,” said David Raichlen, a professor of biological sciences and anthropology at the USC Dornsife College of Letters, Arts and Sciences and senior author of the study.
Researchers published the findings July 10 in Alzheimer’s & Dementia, the flagship journal of the Alzheimer’s Association, drawing on data from 1,712 adults enrolled in the long-running Atherosclerosis Risk in Communities study. Participants reported their TV-watching and workday-sitting habits between 1987 and 1989, then underwent brain MRI scans more than two decades later, between 2011 and 2013.
Compared with people who said they never or seldom watched TV, those who watched it “very often” showed smaller frontal and occipital lobe volumes, reduced volume in regions associated with early Alzheimer’s disease and higher levels of white matter hyperintensities, a marker of small-vessel brain damage tied to stroke risk and cognitive decline. Those differences held up even after researchers accounted for physical activity, smoking, diabetes and body mass index.
Related: The TV Rating System Is Broken. What Are You Going to Do to Fix It?
Sitting itself, oddly enough, wasn’t the culprit. Adults who reported sitting through long workdays actually had larger frontal and occipital lobes and less white matter damage than the heaviest TV watchers.
“We frequently encourage the public not to spend too much time sitting down, but experts may want to expand that recommendation to encompass the activities done while sitting, since those seem to have distinct impacts on brain health,” said Natan Feter, the study’s corresponding author and a postdoctoral scholar in USC Dornsife’s Human and Evolutionary Biology program.
Researchers suspect mental engagement makes the difference. Desk work tends to involve planning, problem-solving and decision-making, while television asks little of the brain beyond following along. The study also found men’s brains showed far more of these changes than women’s, though researchers aren’t yet sure why the effect skews by sex.
The findings hand Christian parents another data point in the case for screen-time limits, not as a legalistic rule but as basic stewardship of the mind God gave each of us. Scripture never mentions an MRI, but Proverbs 4:23 offers old wisdom that fits a new study: “Above all else, guard your heart, for everything you do flows from it.” A mind shaped by passive hours in front of a screen is a different thing than one renewed by conversation, work, and purposeful rest, and Movieguide® has long argued that what families watch, and how much, is worth weighing carefully.
The study’s authors caution that their data relies on self-reported viewing habits rather than device-tracked time, and participants weren’t scanned at the study’s start, so the findings show an association rather than proven cause and effect. Still, the researchers say the takeaway holds: what a person does while sitting still may matter as much as how long they sit.
Read Next: Does YouTube Actually Want to Compete With TV?
Questions or comments? Please write to us here.
