Sitting for long hours regularly can be bad for your body and mind. New research suggests that keeping your brain engaged can help fight certain injuries from inactivity.
Being engaged means activities like knitting or solving a puzzle, instead of mindlessly scrolling or staring at the screen.
Scientists at the Karolinska Institute in Stockholm surveyed 20,811 Swedish adults, mostly women between the ages of 35 and 64, about their weekly physical activity and how much time each day they spent “mentally active” and “mentally inactive” when they were doing nothing. They first surveyed participants in 1997 and followed up 19 years later to assess dementia risk and condition.
Sedentary behavior – long periods of sitting, lying down or sitting – is linked to “major risk factors for dementia,” such as high blood pressure, heart disease, diabetes and obesity, said Mats Hallgren, principal researcher at the Karolinska Institute and study author.
However, brain function is an important factor in preventing such damage.
The brain “works like a muscle,” he said. Not using it actively for a long time can end up negatively affecting the parts related to memory and learning.
On the questionnaire, being mentally busy while being sedentary included office work, sitting in a meeting, knitting and sewing. Activities such as using a computer to solve a puzzle are considered intellectually stimulating.
Watching TV or listening to music while sitting still counts as mental inactivity.
In the study, published Thursday in the American Journal of Preventive Medicine, participants who remained mentally inactive had “a significantly greater risk of developing some form of dementia in the future,” Hallgren said.
Concerns about ‘brain rot’ behavior
Using a mathematical model, the researchers then predicted how changes in cognitive function might affect the risk of dementia.
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They calculated that adding an hour of mentally active behavior while sitting reduced the risk of dementia by 4%; replacing an hour of mentally inactive behavior with mentally active behavior reduced the risk by 7%; and combining physical activity, such as walking, with active mental behavior reduced the risk by 11%.
The study has limitations. Because the first questionnaire was almost three decades ago, smartphones, social media and endless scrolling did not exist. Previous reviews have suggested that older adults derive cognitive benefits from phone use, but less is known about children and young adults. And because it is based on self-report, the study cannot conclude whether sedentary activities increase the risk of dementia, or whether people at high risk of dementia may engage in more sedentary activities.
Dr. Hussein Yassine, a professor of neuroscience at the University of Southern California Keck School of Medicine, speculates that phone and social media use may pose a similar risk by affecting our ability to concentrate.
“It will affect your ability to process information and build synapses in certain areas of the brain that help with concentration,” says Yassine. “So the next time you have a difficult task or you need to concentrate, you can no longer work properly because your brain networks have been hijacked by this response.”
Adam Brickman, a professor of neuropsychology at Columbia University, said the rise of short-form content like TikTok has greatly increased passive-aggressive behavior.
“If you think about how kids, and even adults, spend their time watching content that I don’t think any of us would classify as motivational or active behavior, it’s much higher today than it was in 1997,” said Brickman, who was not related to the new study.
Recent research has raised concerns about cognitive decline, popularly known as “brain rot,” including short attention spans that may accompany heavy use of short-form video.
“This kind of mindless scrolling from one YouTube video to the next, those kinds of sedentary behaviors, if repeated over time, are more likely to be associated with depression and anxiety and stress-related conditions, compared to active engagement and work-like scrolling,” he said.
Even though technology has changed, “the mechanisms that affect dementia are fundamentally the same for people today as they were 30 years ago,” Hallgren said.
His advice for reducing the risk of dementia is simple: “Sit still and move often, often.”
