How much TV you watch as a young adult may affect midlife
Watching a lot of TV and having a low physical activity
level as a young adult were associated with worse cognitive function 25 years
later in midlife, according to an article published online by JAMA
Few studies have investigated the association between
physical activity in early adulthood and cognitive function later in life.
Coupled with the increasing prevalence of sedentary or screen-based activities,
such as watching television, these trends are of concern for upcoming
generations of young people.
Tina D. Hoang, M.S.P.H., of the Northern California
Institute for Research and Education at the Veterans Affairs Medical Center,
San Francisco, Kristine Yaffe, M.D., of the University of California, San
Francisco, and coauthors examined associations between 25-year patterns of
television viewing and physical activity and midlife cognition.
The study of 3,247 adults (ages 18 to 30) used a
questionnaire to assess television viewing and physical activity during
repeated visits over 25 years. High television viewing was defined as watching
TV for more than three hours per day for more than two-thirds of the visits and
exercise was measured as units based on time and intensity. Cognitive function
was evaluated at year 25 using three tests that assessed processing speed,
executive function and verbal memory.
Participants with high television viewing during 25 years
(353 of 3,247 or 10.9 percent) were more likely to have poor cognitive
performance on some of the tests. Low physical activity during 25 years in 528
of 3,247 participants (16.3 percent) was associated with poor performance on
one of the tests. The odds of poor cognitive performance were almost two times
higher for adults with both high television viewing and low physical activity
in 107 of 3,247 (3.3 percent) participants, according to the results.
The authors acknowledge a few limitations, including
possible selection bias and that physical activity and TV viewing were
“In this biracial cohort followed for 25 years, we
found that low levels of physical activity and high levels of television viewing
during young to mid-adulthood were associated with worse cognitive performance
in midlife. In particular, these behaviors were associated with slower
processing speed and worse executive function but not with verbal memory.
Participants with the least active patterns of behavior (i.e., both low
physical activity and high television viewing time) were the most likely to
have poor cognitive function. … Individuals with both low physical activity
and high sedentary behavior may represent a critical target group,” the
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