The secret to keeping your brain sharp may be staying active. A longitudinal study from the University of California, San Francisco finds that watching television and being inactive are linked with reduced cognitive skills. The study highlights the complex milieu of factors that contribute to physical and mental health.
For the study, the researchers followed more than 3,200 people for 25 years, from young adulthood through middle age. The researchers checked in with the participants at regular intervals. Every five years, they asked participants to report how much television they watched daily. Every two to five years, they evaluated how much exercise participants did. At the end of the 25-year period, the researchers conducted three tests to measure participants’ memory, focus, and mental quickness.
Exercising less and watching a lot of television was linked to worse cognitive performance. The participants who did not do much exercise or who watched three or more hours of television per day performed worse on tests of cognitive focus and speed than participants who exercised more or watched less television. Participants who had both a low level of physical activity and a high level of television viewing performed even worse on the cognitive tests.
While the research demonstrates an association between exercise, television, and cognitive function, it does not explain why they are connected. There are a number of possible explanations for the study results. It is possible that watching television is linked with poor cognitive performance because inactivity reduces brain power. It is also possible that watching television does not do enough to challenge the brain, leading to weakened cognitive skills. The researchers did not test the participants’ cognitive skills at the beginning of the study. It may be that people with lower scores are just more likely to watch a lot of television.
Regardless of the cause, it is clear that being physically active is related to better cognitive function in middle-aged adults. The finding could have an impact on understanding the cognitive decline that occurs as people age.
This research is published in JAMA Psychiatry.