Couch potatoes, rejoice: lounging around might not be so bad — at least for your brain.
While exercise is known to help lower dementia risk, new research suggests that even a small change in how you spend your time sitting could also make a difference.
That’s welcome news for Americans, who spend an average of 9.5 hours a day glued to their seats, whether at work or relaxing at home.
“Sedentary behavior is common, but fortunately, it can also be modified,” Mats Hallgren, lead author of the study and senior researcher at the Karolinska Institute in Sweden, said in a press release.
“Our study shows that not all sitting is the same — how we use our brains while sitting may be an important factor for future cognitive and mental health,” he added.
To dig deeper into how our sedentary habits influence cognition, Hallgren and his colleagues followed 20,811 Swedes aged 35 to 64 over nearly two decades.
At the start, the participants filled out detailed questionnaires about their daily habits, including how much time they spent on passive activities, like watching TV or listening to music, versus mentally active ones, such as office work, knitting, playing cards or other brain-engaging tasks.
On average, they reported 116.3 minutes per day of passive sitting and 239.9 minutes per day of mentally active sitting.
Fast forward 19 years, and the researchers checked Sweden’s national health records to see who developed dementia, a syndrome marked by gradual declines in memory, thinking and communication skills that interfere with daily life.
During that time, 569 participants were diagnosed, and the findings suggested that how they spent their sitting time could have played a role.
The researchers found that each extra hour per day of mentally active sitting was linked to a 4% lower risk of dementia. Even better, swapping one hour of passive sitting for an hour of mentally active sitting cut dementia risk by 7%.
“We found that longer periods of mentally passive sedentary behavior were associated with a higher risk of dementia,” Hallgren explained. ‘When passive sitting was instead replaced with mentally active activities, the risk decreased.”
Interestingly, the benefits of mentally active sitting were stronger for participants aged 50 to 64 than for those in their late 30s and 40s, suggesting older adults might get more brain protection from keeping their minds busy while taking some physical downtime.
The researchers suspect something called cognitive reserve could be at play.
Cognitive reserve acts like a mental safety net, helping your brain improvise and find new ways to get things done, keeping you sharp even as aging, disease or injury take their toll.
The study authors suggest that mentally active work in midlife may build this reserve, with its protective effects only showing up later in life.
Imaging studies back this up, showing real changes in both the structure and function of adults’ brains who stay mentally active through work, social activities and other intellectual pursuits.
The researchers also theorized that older adults might get an extra brain boost from how they spend their sitting time — engaging in cognitively stimulating leisure activities like reading, writing or doing puzzles — while younger adults, often stuck sitting at work, may get mental stimulation but also higher levels of stress.
“While all sitting involves minimal energy expenditure, it may be differentiated by the level of brain activity,” Hallgren said.
“How we use our brains while we are sitting appears to be a crucial determinant of future cognitive functioning and, as we have shown, may predict dementia onset.”
But the study had its limits.
For one, participants reported their habits back in 1997, long before smartphones, social media and endless streaming took over. Their routines also likely changed over the 19-year follow-up, something the data didn’t capture.
Still, Hallgren said the findings are worth paying attention to, especially in today’s sedentary world. Across the US, only 1 in 4 adults and 1 in 5 adolescents meet physical activity guidelines for aerobic and muscle-strengthening activities — meaning most people are logging way too many hours in their chairs.
“Our study adds the observation that not all sedentary behaviors are equivalent; some may increase the risk of dementia, while others may be protective,” Hallgren said.
“It is important to remain physically active as we age, but also mentally active-especially when we are sitting.”
After all, if a small tweak while sitting could help fend off dementia, it might be worth swapping a little couch time for some brain-boosting activity.
Across the country, about one in 10 older adults are living with dementia, the most common form being Alzheimer’s disease.
As the US population ages, those numbers are expected to soar. Researchers estimate that 42% of Americans over 55 will eventually develop dementia, with women and Black adults facing higher risks.
By 2060, cases nationwide are projected to double, with roughly 1 million new diagnoses each year.
