Research has also shown prolonged sitting can contribute to the development of cancer, back pain, and many other health issues.

The Connection Between Sitting and Dementia

To analyze the link between a sedentary lifestyle and dementia, the researchers turned to the UK Biobank, a medical data repository on half a million people living in the United Kingdom. 

The database had information on nearly 50,000 people aged 60 or older who wore accelerometers, which are wrist devices that track movement, continuously for one week sometime between 2013 to 2015. None of the people had dementia when they began wearing the accelerometer.

Researchers for the new study used medical records to determine that, about six years after people participated in the week-long experiments, 414 of them had developed dementia.

After analyzing the accelerometer data, they found that a participant's risk of developing dementia increased if they spent about 10 waking hours a day sedentary, meaning they were sitting or reclining and expending little energy (riding a bike, for example, would not have been considered sedentary, according to Aslan).

The risk shot up from there, with participants who were sedentary for 15 waking hours having triple the chance as their non-sedentary counterparts of developing dementia.

“The number of sedentary bouts per day was not associated with higher risk of incident dementia,” the researchers wrote. Instead, the total number of sedentary hours was what mattered.

“This is a very important study, “ said Schultz. “Instead of relying on subjective feelings about exercise, they used objective wrist detectors. And there was five to eight years of follow up, which in the over 60 age group is typically enough to pick up differences in dementia risk between groups.”

However, she pointed out that the study didn’t analyze sedentary behavior in younger people, so it’s still unclear whether something like a career-long desk job might impact future dementia risk. 

“While not fully understood, reduced physical activity leads to a range of negative effects, including weight gain, increased inflammation, and reduced blood flow to the brain,” she said. “Combined, these factors may increase a person’s dementia risk, most likely due to direct and indirect damage to brain cells.” 

How To Avoid Being Sedentary

Schultz said that dementia specialists believe lifestyle changes can reduce the risk of developing symptoms by as much as 50%—which seems like a compelling reason to get moving.

One way to stay active is to find something you enjoy, experts said, whether that's taking a dancing class or walking in the neighborhood. 

And, suggested Schulz, it helps to get your spouse or partner on board. “If the spouse decides that they need to help their loved one by both of them exercising, then our patients, I find, are much more likely to engage in regular exercise,” he said.

While the study suggests that just being non-sedentary for fewer than 10 hours a day can benefit brain health, Fredericks said that 30 minutes of that non-sedentary time should be devoted to moderate-intensity cardio, such as jogging or swimming. 

“If you are already getting enough aerobic exercise, strength training, flexibility, and balance exercises are also key for both brain health and preventing injury,” Caldwell added.

If you have limited mobility, Aslan pointed out other strategies for keeping your brain sharp. "People may be able to find other ways to reduce their risk of dementia, like engaging in more cognitively active tasks while being sedentary, such as solving puzzles, reading, or using a computer," he said.