Researchers from the University of California at San Francisco, working with the Veterans Affairs Medical Center and other research agencies, have found that watching television may affect cognition, specifically as it relates to executive function and processing speeds.

The study followed 3,247 people over a 25-year period, beginning in their early adult years. Those that frequently watched television during their early adult years had a 64 percent higher incidence of poor cognitive performance compared to less frequent television watchers. This was after adjusting results for the effects of many other known lifestyle factors that affect cognition such as smoking, alcohol use and body mass index.

The effects of television watching worsened when combined with reduced physical activity during young adult years. Those with low physical activity and a high frequency of watching television were twice as likely to have poor cognition compared to those that had low television viewing combined with high physical activity during that period.