Too much sitting may lead to cognitive decline, dementia: study

Los Angeles — Long periods of inactivity may lead to atrophy of the part of the brain responsible for memory, according to a preliminary study from the University of California, Los Angeles.

Researchers surveyed 35 people between the ages of 45 and 75 who did not have dementia about their physical activity levels and the average hours per day they spend sitting over a seven-day period. Participants also underwent MRIs, which provided a high-resolution image of the medial temporal lobe, the region of the brain involved in the formation of new memories.

The researchers – who cited past research on the connection between physical activity and the delay of the onset of dementia and Alzheimer’s disease – found that more sitting led to thinner medial temporal lobes, which can be an early sign of cognitive decline and dementia in middle-aged and older adults. They stress, however, that their findings do not prove that excessive sitting causes thinner brain structures – only that increased sedentary time is associated with thinner brain regions.

“The finding … is clinically relevant and suggests that reducing this behavior may be a possible target for interventions designed to improve brain health in middle-aged and older adults,” the researchers said. “Better understanding the effects of sedentary behavior on our brains is important given the global epidemic of physical inactivity and sedentary lifestyles.”

The researchers also concluded that physical activity, no matter the level, does not compensate for the harm done by sitting for extended periods.

The study was published April 12 in the journal PLOS ONE.