US researchers have published preliminary studies that show that sitting down for too long can reduce the thickness of the medial temporal lobe, a brain structure that is very involved in memory. This alteration could eventually be responsible for Alzheimer’s disease.
Neuroscience and epidemiology studies suggest that exercise is a promising way to delay the onset of Alzheimer’s disease. This is due to a beneficial effect of physical activity on several brain structures involved in memory and cognition. However, physical activity does not appear to alter the thickness of the medial temporal lobe.
The authors of a recently published study note that, however, the effect of staying seated for a long time in the day on the brain is less studied and therefore less clear. To find out more, the researchers recruited 35 people who did not have dementia, aged between 45 and 75 (25 women, 10 men). All volunteers underwent MRI to assess medial temporal lobe thickness, which was found to be normal. They also completed a questionnaire about their physical activity patterns and the number of hours spent in a sitting position. All have also passed memory tests.
The researchers then invited the participants to spend between 3 and 15 hours a day in the sitting position. Surprisingly, it was found in imaging that, in the participants who spent between 3 and 15 hours a day sitting down, the thickness of the medial temporal lobe decreased, potentially exposing them to the risk of developing Alzheimer’s disease.
The conclusions of this preliminary study are that, although a sedentary lifestyle has an effect on the brain that can lead to Alzheimer’s disease, physical activity was also associated with a smaller decrease in medial temporal lobe thickness. The authors conclude that further studies are needed to understand the relationships between physical inactivity, physical activity, brain transformations and Alzheimer’s disease.