Sitting all day tied to risk of dementia

Study says effects may top exercise

In news that we shouldn’t take sitting down, a study just published in JAMA finds that people who stay seated for long hours at work and home are at much higher risk of developing dementia than people who sit less.

The negative effects of extended sitting can be so strong, researchers found, that even people who exercise regularly face higher risk if they sit for much of the day.

The study, which involved 49,841 men and women aged 60 or older, “supports the idea that more time spent in sedentary behaviors increases one’s risk of dementia,” said Andrew Budson, a professor of neurology at Boston University and coauthor of “Seven Steps to Managing Your Aging Memory,” who was not involved with the study.

The results also underscore just how pervasive the consequences of sitting can be, affecting our minds, as well as our bodies, and they hint that exercise by itself may not be enough to protect us.

The downsides of oversitting are well known to scientists and most of the rest of us. Past research shows that people who sit throughout the day, accumulating multiple hours of sedentary time at the office, commuting, and at home, in front of televisions and computers, are more likely to develop heart disease, obesity, diabetes, and other illnesses and die prematurely than people who often get up and move around.

Sitting can even undermine exercise. According to other recent research, people who work out but then sit for the rest of the day wind up erasing some of the expected metabolic benefits of their exertions.

But whether sitting likewise affects brain health hasn’t been as clear. Some studies have linked sitting and later memory problems, including Alzheimer’s disease and other forms of dementia. But they’ve mostly relied on people’s recall of how much they sit, which can be inaccurate.

So, for the new study, scientists at the University of Southern California in Los Angeles and other universities sought objective measures of sitting, and found it in the UK Biobank, a large repository of data about the lives, health, and deaths of hundreds of thousands of British men and women.

Many of the Biobank participants wore a sophisticated activity tracker for a week after joining the study to minutely record their movements — and stillness — throughout the day.

The scientists pulled records for almost 50,000 of these men and women aged 60 or older who didn’t have dementia when they joined the study.

If the men and women sat for at least 10 hours a day, their risk of developing dementia within the next seven years was 8 percent higher than if they sat for fewer than 10 hours.

The risks ballooned from there, reaching a 63 percent greater risk of dementia for people who spent at least 12 hours chair-bound.