For many people, relaxing means settling onto the sofa and switching on the television. It's an easy way to unwind after a busy day, but new research suggests that not every way of spending downtime affects the brain in the same way.
Researchers at the University of Southern California, writing in Alzheimer's & Dementia, found that frequent television viewing during midlife was associated with brain differences decades later.
Their findings suggest that the activity people choose while sitting may matter as much as the time they spend sitting, reports Science Daily.
A different pattern
The team analysed data from about 1,700 adults taking part in the long-running Atherosclerosis Risk in Communities (ARIC) study. Participants reported their television habits during midlife, and more than 20 years later underwent MRI brain scans.
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People who said they watched television very often were more likely to have smaller brain regions involved in memory, decision-making and visual processing. They also showed more signs of changes in the brain's white matter, which previous research has linked to cognitive decline and dementia.
More than screen time
One of the study's most notable findings was that sitting at work did not show the same association. Participants with desk-based jobs often had healthier brain measurements than those who spent much of their free time watching television.
The researchers suggest that mentally demanding activities such as planning, analysing information and solving problems may help keep the brain active, even while people remain physically inactive.
The findings remained after accounting for factors including exercise, smoking, alcohol use, diabetes and body weight.
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- Around 1,700 adults were followed for more than two decades.
- Frequent TV viewing was linked to several long-term brain differences.
- The study found an association, not proof of cause and effect.
The researchers caution that the study cannot show television directly caused the observed brain changes, and participants' viewing habits were self-reported.
Even so, the findings add to growing evidence that brain health may depend not only on how long people sit, but also on how they choose to spend that time.
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