Sitting might be a comfortable and convenient way to spend much of your day, but a new study of older adults suggests it can lead to brain shrinkage and cognitive issues, irrespective of how much exercise you're managing to fit in.
The research counters the idea that periods of sitting can be balanced out by periods of being active, at least when it comes to brain health in people aged 50 or above.
The study researchers, from Vanderbilt University, the University of Pittsburgh, and Seoul National University, think that too much sitting or lying down (known as sedentary behavior) can impact the brain and increase the risk of different types of dementia later in life, including Alzheimer's disease.
"Reducing your risk for Alzheimer's disease is not just about working out once a day," says neurologist Marissa Gogniat, from the University of Pittsburgh.
"Minimizing the time spent sitting, even if you do exercise daily, reduces the likelihood of developing Alzheimer's disease."
The researchers recruited 404 volunteers, tracking their activity levels with wearables over the course of a week. Then, over the next seven years, cognitive tests and brain scans were used to assess their brain health.
Even though 87 percent of the volunteers were meeting the recommended weekly guidelines of at least 150 minutes of moderate-intensity exercise, those who sat more overall showed worse cognition.
They also showed more signs of neurodegeneration – including a faster thinning of the hippocampus, a part of the brain crucial to memory function and one of the first areas to show damage from Alzheimer's.
The association wasn't huge, and doesn't prove direct cause and effect, but it was noticeable: spending more time sitting seems to age the brain faster, and reducing that amount of time, rather than just exercising more, appears to be the best antidote.
Stronger associations were found in those already at a higher genetic risk of Alzheimer's, the data shows.
"This research highlights the importance of reducing sitting time, particularly among aging adults at increased genetic risk for Alzheimer's disease," says neurologist Angela Jefferson, from the Vanderbilt University Medical Center.
"It is critical to our brain health to take breaks from sitting throughout the day and move around to increase our active time."
Of course, these findings aren't a reason to give up more vigorous exercise. We know that being active does wonders for our physical and mental health, and even small amounts of exercise can keep the brain sharp.
What's most important here is that extra hours sitting down were linked to certain kinds of wear and tear in the brain. This isn't the first time that sedentary behavior has been linked with dementia and Alzheimer's, but it's another important and comprehensive set of data that researchers and health professionals can draw on.
"It is critical to study lifestyle choices and the impact they have on brain health as we age," says Jefferson.
The research has been published in Alzheimer's & Dementia.