Sitting too much interferes with “mental skills that help people plan, organize and pay attention.” That’s what California researchers found when they followed 3,200 study participants’ television watching and exercise habits over twenty-five years.
Those who watched more than 3 hours of television a day performed worse on three tests of cognitive function “that assessed the speed at which they processed information, their verbal memory and executive function.” Those “who both exercised the least and watched more than 3 hours of TV per day were twice as likely to perform poorly on the cognitive tests, compared with those who spent little time watching TV but exercised more.
“It is not clear exactly why spending more time watching TV may be linked to worse cognitive performance later in life. One hypothesis is that television viewing is not a cognitively engaging way of spending time, Hoang said.
“Or it could be that people who watch a lot of TV and don't exercise much may have other unhealthy lifestyle habits, such as a poor diet, which might also contribute to their worse cognitive function, she said.”
Previous studies linked television watching to further cognitive decline, Alzheimer’s. One study found those who were physically inactive and whose primary recreational activity from ages 40 to 59 was television watching increased their risk for Alzheimer’s by 250%. Another found each one hour of television viewing from the ages 40 to 59 increases the risk of Alzheimer’s Disease by 1.3 times. Since 46% of the risk for Alzheimer’s is associated with heredity and 21% with physical inactivity, it could explain why television watching is especially detrimental to the cognitive function of some individuals.