Why Sitting May Be Bad for Your Brain

Sitting for hours without moving can slow the flow of blood to our brains, according to a cautionary new study of office workers, a finding that could have implications for long-term brain health. But getting up and strolling for just two minutes every half-hour seems to stave off this decline in brain blood flow and may even increase it.

Delivering blood to our brains is one of those automatic internal processes that most of us seldom consider, although it is essential for life and cognition. Brain cells need the oxygen and nutrients that blood contains, and several large arteries constantly shuttle blood up to our skulls.

Because this flow is so necessary, the brain tightly regulates it, tracking a variety of physiological signals, including the levels of carbon dioxide in our blood, to keep the flow rate within a very narrow range.

But small fluctuations do occur, both sudden and lingering, and may have repercussions. Past studies in people and animals indicate that slight, short-term drops in brain blood flow can temporarily cloud thinking and memory, while longer-term declines are linked to higher risks for some neurodegenerative diseases, including dementia.

Other research has shown that uninterrupted sitting dampens blood flow to various parts of the body. Most of those studies looked at the legs, which are affected the most by our postures, upright or not. Stay seated for several hours, and blood flow within the many blood vessels of the legs can slacken.

Whether a similar decline might occur in the arteries carrying blood to our brains was not known, however.

So for the new study, which was published in June in the Journal of Applied Physiology, researchers at Liverpool John Moores University in England gathered 15 healthy, adult, male and female office workers.

The scientists wanted to recruit people who habitually spent time at a desk since, for them, long hours of sitting would be normal.

The researchers asked these men and women to visit the university’s performance lab on three separate occasions. During each, they were fitted with specialized headbands containing ultrasound probes that would track blood flow through their middle cerebral arteries, one of the main vessels supplying blood to the brain.