How much time do you spend sitting each day?
If you’re like many Americans, you spend about 40 percent of your workday plunked on a chair, according to the Bureau of Labor Statistics, and probably a lot more if you work in an office. That shakes out to somewhere between six and 10 hours a day, depending on your age, behavioral researcher Deborah Young told the American Heart Association.
Scientists have been warning for some time that all that sitting is doing damage to the heart and other muscles. Now a new study from UCLA suggests that sitting for too long actually causes a key part of the brain responsible for making memories to “thin” – and exercise doesn’t stop it.
For the study, published in the journal PLOS One, scientists looked at 35 people ages 45 to 75 and asked them how long they’d spent sitting and how much they had exercised over the previous week. Then they gave each person a detailed brain scan that provided a close look at the medial temporal lobe (MTL), a region of the brain that plays a key role in forming new memories.
The researchers found that people who sat for more of the day had significantly thinner brain structures. The researchers also found that exercising, even at high levels, did not reverse or offset the damage.
The researchers wrote than an undersized MTL can be a troubling warning sign of memory problems.
“MTL thinning can be a precursor to cognitive decline and dementia in middle-aged and older adults. Reducing sedentary behavior may be a possible target for interventions designed to improve brain health in people at risk for Alzheimer’s disease,” the researchers said in a news release.
The study doesn’t prove that sitting causes damage to the brain but does highlight a connection between sitting more often and having thinner structures in the MTL. The reason behind that connection is “uncertain,” the researchers say, though they speculate that sedentary behavior might increase inflammation and hurt the brain’s ability to generate new cells and blood vessels.
The next step, the scientists wrote, is to look at other factors that might come into play such as race, gender and weight, as well as what kinds of activities people were doing while sitting. For example, the scientists wrote there may be a difference between those who were “mentally active sitting” while solving crossword puzzles or writing, and those who were “mentally inactive sitting” while watching TV or playing games.
The results are the latest in a growing pile of evidence that excessive sitting can lead to serious risks. Another study published in 2017 found that risk of early death increases along with the amount of time people spend sitting. In that study, too, the researchers found that exercising didn’t seem to have much of an effect.
“The more we sit the worse it is. The longer the duration of sitting, the more negative the impact on our cardiovascular health,” Dr. Suzanne Steinbaum, a director of women’s heart health in New York, told CNN.
There are some ways to break out of the sitting habit, however. Scientists told The Washington Post they recommended doing things like sitting on a medicine ball instead of a chair, stretching the hips, walking around during commercials, and switching between standing and sitting while on the computer.