The unhealthiest way to sit: ‘Intellectually sedentary’ people at higher risk of dementia

LOS ANGELES – Older adults, even those who sit for lengthy periods of time, should pursue intellectually stimulating activities to reduce their risk of dementia, a study reveals.

A collaborative team of biological science and media researchers at the University of Southern California say that exercising one’s mind may be just as important as exercising one’s body. People over the age of 60 who watch television and passively engage in similar “intellectually sedentary” activities are placing themselves at a higher risk of developing dementia. On the other hand, older adults who read, do crossword puzzles, or work on computers are helping to lower their risk of developing dementia by keeping their brains active.

Sitting for long periods of time reduces blood flow to the brain. However, the researchers say that “greater intellectual stimulation that occurs [even] during computer use may counteract the negative effects of sitting.”

“We know from past studies that watching TV involves low levels of muscle activity and energy use compared with using a computer or reading,” says study co-author David Raichlen in a university release. “And while research has shown that uninterrupted sitting for long periods is linked with reduced blood flow in the brain, the relatively greater intellectual stimulation that occurs during computer use may counteract the negative effects of sitting.”

Just using your brain can offset the damage from sitting

The team of USC and University of Arizona researchers found people who practiced passive mental activities such as watching TV had a higher risk of dementia onset – regardless of whether or not they were physically active. The researchers reiterated that what older adults do while they’re sitting is crucial to brain health and to warding off cognitive decline in their later years.

Activities which stimulate the brain offset even the large amount of time older adults spend sitting in place. The authors add that the risk for developing dementia dropped among older adults who were intellectually active, even if they failed to engage in enough physical exercise.

The study tracked 145,000 older adults who did not have a diagnosis of dementia between 2006 and 2010. Using inpatient hospital records and other self-reported medical data, the researchers found that 3,507 positive cases ultimately turned up among the group sample over the course of 12 years.

“Although we know that physical activity is good for our brain health, many of us think that if we are just more physically active during the day, we can counter the negative effects of time spent sitting,” says study author Gene Alexander, a professor of psychology at the University of Arizona’s Evelyn F. McKnight Brain Institute.

‘What we do while we’re sitting matters’

The study corroborates a wide range of past research which warns older adults against settling for sedentary lifestyles and other activities which do not stimulate the mind. Radboud University Medical Center research published in 2018 found a direct correlation between sedentary behavior and dementia patients. The new research takes that a step further.

“Our findings suggest that the brain impacts of sitting during our leisure activities are really separate from how physically active we are,” Alexander says, “and that being more mentally active, like when using computers, may be a key way to help counter the increased risk of dementia related to more passive sedentary behaviors, like watching TV.”

“What we do while we’re sitting matters,” Raichlen continues, noting how older adults can now make changes to their leisurely activities. “This knowledge is critical when it comes to designing targeted public health interventions aimed at reducing the risk of neurodegenerative disease from sedentary activities through positive behavior change.”

The study is published in the journal Proceedings of the National Academy of Sciences.

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