There's been lots of research into how too many hours lounging on chairs and sofas can harm the heart. Now, researchers say all that sitting might be bad for your brain, too.

A new study found that too much time spent sitting was correlated with an unhealthy "thinning" of tissue in a key brain area tied to memory.

And it appears that the link isn't simply due to the fact that folks who sit for hours each day aren't exercising -- there was something about the act of sitting itself that seemed to be key..

"We found that sedentary behavior, but not [levels of] physical activity, was associated with less thickness of the medial temporal lobe," a brain region that's crucial to the formation of new memories, explained a team led by Prabha Siddarth.

Siddarth is a biostatistician at the University of California, Los Angeles' Semel Institute of Neuroscience and Human Behavior.

One brain specialist called the research early, but "intriguing."

While the study can't prove that sitting helped cause the brain tissue thinning, the research "bears further exploration," said Dr. Marc Gordon, chair of neurology at Zucker Hillside Hospital in Glen Oaks, N.Y.

In the study, Siddarth's group asked 35 people, aged 45 to 75, about their physical activity levels and the average amount of time they spent sitting each day during the previous week. Each participant also underwent a scan of their medial temporal lobe.

Study participants who spent a lot of time sitting were more likely to have thinning of this brain region, the investigators found. And that included even those people who had relatively high levels of physical activity when they weren't sitting.

As Gordon noted, however, "not all sitting behavior is necessarily equal, and what people are doing while they are seated may have different effects [on brain health]."

Siddarth's team explained that "it is possible that there may be two distinct groups: mentally active sitting and mentally inactive sitting. In mentally active sitting, individuals may be attending to cognitive demanding tasks such as crossword puzzles, documentation, writing, or computer games. In mentally inactive sitting, individuals may be engaging in less demanding, passive tasks such as watching television or movies."

The study authors also noted that a thinning of the medial temporal lobe is suspected of being a forerunner of mental decline and dementia in middle-aged and older adults.

So, it's plausible that reducing the amount of time spent sitting could be a way to improve brain health in people at risk for Alzheimer's disease and other types of dementia, the researchers suggested.

And not only the brain might be helped: Prior research has shown that too much sitting increases the risk of heart disease, diabetes and premature death, the study authors noted.

Siddarth's team said it wants to conduct a long-term study to determine if too much sitting actually helps cause a thinning of the medial temporal lobe.