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TV Viewing rots the brain | Blog | County Pathology Ltd

TV Viewing rots the brain

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High TV Viewing, Low Activity Linked to Poorer Cognition
Watching television for 3 hours or more a day in young adulthood, coupled with low levels of physical activity, may lead to poorer cognitive function in midlife, the first study of its kind suggests.

Lead author Tina Hoang, MSPH, Northern California Institute for Research and Education, San Francisco, and senior author Kristine Yaffe, MD, University of California, San Francisco, found that young adults aged approximately 25 years who watched television for 3 hours or more a day demonstrated poorer performance on several measures of executive function and processing speed 25 years later compared with those watching less.

When coupled with low levels of physical activity, watching a lot of television in young adulthood almost doubled the risk of performing poorly on the same measures of cognitive function in midlife.

"Our results indicate that the lifestyle behaviors in early adulthood that were evaluated in this study could have an effect on the risk of cognitive impairment in midlife," Hoang and colleagues observe.

"And they support a potential role for both physical activity and sedentary behavior as modifiable risk factors for prevention."

The study was published online December 2 in JAMA Psychiatry.

Young adults aged 18 to 30 years were recruited from population-based samples of four US cities.

The study was carried out from 1985 to 2011. Follow-up examinations were performed every 2 to 5 years over a 25-year period.

At years 5, 10, 15, 20, and 25, participants were asked how many hours a day, on average, they spent watching television. A pattern of high television viewing over 25 years was defined as activity levels within the top quartile of year 5 ― namely, 3 hours a day or more during two thirds of the visits.

At year 25, interviewers administered three cognitive tests: the Digit Symbol Substitution Test (DSST), which assesses processing speed and executive function; the Stroop test, which assesses executive function; and the Rey Auditory Verbal Learning Test (RAVLT), which assesses verbal memory.

Compared with participants with moderate to high long-term patterns of physical activity, young adults with low levels of physical activity were 47% more likely to do poorly on the DSST.

A total of 353 participants, or approximately 11% of the cohort, met the criteria for a long-term pattern of high television viewing.

"This high level [of television viewing] was associated with poor cognitive performance at year 25 on all cognitive tests," Hoang and colleagues report.