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Too Much Sitting May Shrink the Part of Your Brain Tied to Memory

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It may be time to ditch the desk chair: A new study links sitting too much each day with memory problems in middle-age and older adults.

Researchers from the University of California, Los Angeles (UCLA) found that long stretches of sedentary behavior — like spending all day in your desk chair — were linked to changes in a part of the adult brain that's critical for memory.

Earlier research has linked sedentary behavior to an increased risk of heart disease, diabetes and premature death in middle-age and older adults. The new study, published yesterday (April 12) in the journal PLOS One, builds on this, focusing on inactivity's impacts on the brain, according to a statement from the researchers.

Specifically, the new study linked sedentary behavior to thinning of the medial temporal lobe, a brain region involved in the formation of new memories, the researchers said in the statement. Brain thinning can be a precursor to cognitive decline and dementia in middle-age and older adults, the researchers added. [Don't Sit Tight: 6 Ways to Make a Deadly Activity Healthier]

The study included 35 people between the ages of 45 and 75. Researchers asked the participants about their physical activity levels and the average number of hours per day they'd spent sitting over the previous week.

Then, the researchers scanned the participants' brains. Using a high-resolution MRI scan, the scientists got a detailed look at the medial temporal lobe of each participant and identified relationships among this region's thickness, the participants' physical activity levels and their sitting behavior, according to the study.

The results showed that sitting for extended periods of time was closely associated with thinning in the medial temporal lobe, regardless of one's physical activity level. In other words, the study suggests that "sedentary behavior is a significant predictor of thinning of the [medial temporal lobe] and that physical activity, even at high levels, is insufficient to offset the harmful effects of sitting for extended periods," the researchers said in the statement.

The participants reported that they spent from 3 to 7 hours, on average, sitting per day. With every hour of sitting each day, there was an observed decrease in brain thickness, according to the study. 

And although the study found no significant correlations between physical activity levels and thickness of the medial temporal lobe, the researchers said in the statement that "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 noted that the study didn't prove that sitting led to thinner brain structures, but instead found an association between sitting for long periods of time and thinning structures.

In addition, thefindings are preliminary, and although the studyfocused on hours spent sitting, it did not take into consideration whether participants took breaks during long stretches of sedentary behavior. This, researchers said, could be a limitation of their results. 

Going forward, the researchers said they plan to survey people that sit for longer periods of time each day, in order to determine if sitting causes the observed thinning. They would also like to explore the role gender, weight and race play in the effect on brain health to sitting, according to the statement.

Originally published on Live Science.

Samantha Mathewson
Space.com Contributor