Excessive TV Causes Cognitive Impairment and Earlier Death
How much television do you watch? Most of us realize that watching TV is a passive activity. Part of this passive activity requires we sit down. And stay there – at least while we’re watching. It also replaces activity that requires us to get up and move around. And when we get up and move around, we typically end up walking.
So you could say that watching TV is definitely less healthy compared to walking and doing things that require physical activity. But this should be true if we were sitting down doing anything, right? When we are sitting at the computer for example. Or if we were sitting down exchanging stories with friends of family.
Not so fast. Depending upon how it is used, watching television is apparently quite different from these other sitting activities, with respect to ones mental activity.
Watching more TV reduces cognitive performance later
Research from the Veterans Affairs Medical Center and San Francisco’s Northern California Institute for Research and Education, together with scientists from the University of California at San Francisco, conducted a 25-year study on watching television and cognition.
The researchers followed 3,247 people over this 25-year period. The study tracked people from their early adult years through 25 years later. Their average age at the beginning of the study was 25 years old.
The researchers used three tests to gauge the cognition levels of the subjects. These included the Digit Symbol Substitution Test (DSST), the Stroop test, and the Rey Auditory Verbal Learning Test. These measured cognitive executive function as well as processing speed – in addition to other cognitive functions.
The researchers then divided the people into four groups, depending upon the number of hours they watched television per day. Those who watched more than three hours of TV per day during the 25-year period were put in the high television-viewing group.
Approximately 11 percent of the whole population in this study was considered high television watchers. This totaled 353 of the entire group. There were 528 low television watchers among the population, adding up to 16 percent.
At the end of the 25 years, those in the high television-watching group were 64 percent more likely to score poorly on the DSST test and 56 percent more likely to have poor scores on the Stroop test. There were no significant differences for the Rey Auditory test.
These results were calculated after adjusting for other factors that tend to increase cognitive impairment – including lack of exercise. This means the numbers are specific to television rather than a lack of exercise caused by sitting down excessively in general.
Other potential causes for poor cognition removed from the equation included smoking, alcohol use, body weight and high blood pressure.
Low physical activity increases odds of cognitive decline
The researchers also calculated poor cognition incidence for those who watched more television combined with a lack of regular exercise.
Those subjects who had low exercise levels had low cognition performance on the DSST test an average of 47 percent more than those who exercised more.
This relationship between less exercise and cognitive impairment has also been seen in previous research.
Low physical activity plus more television increases cognitive decline incidence
The researchers then combined those subjects of the group that had low exercise activity with those who watched more television. These people had an even greater incidence of poor cognition 25-years later. Low-exercise, high-television watchers had nearly double the incidence of poor cognition on the DSST test, and more than double (120 percent higher) the incidence of poor cognition on the Stroop test.
Other research finds more TV equals earlier death
This is not the first study that has showed the association between health and television. Another recent study – this from scientists at the U.S. National Cancer Institute at the National Institutes of Health – found that greater TV equates to an earlier death.
The researchers followed 165,087 adults between 50 and 71 years old, beginning in 1994 and ending in 2011. The average follow-up period was 6.6 years.
The researchers found those who watched more than five hours of TV per day had a 28 percent greater incidence of death during the period compared to those who watched less than three hours per day.
The research also followed those who changed their viewing habits one way or another. Those who reduced their TV from more than five hours a day to between three and four hours per day had a 12 percent reduction in their incidence of death during the study period. And those who increased their TV from less than three hours to between three and four hours per day saw their death rates increase by 17 percent.
Finally, those who increased their TV viewing time from less than three hours to more than five hours saw a 45 percent increase in deaths during the period.
Certainly, the takeaway point here – also made by the researchers – was that greater television watching naturally decreases other forms of activity. This displacement so to speak, produces a greater risk of death.
Cognition and TV
In the first study above, potential relationships with other cognitive impairment causes were removed. This allowed the researchers to focus on the two areas – television watching and exercise: Together and separately.
Clearly, they found out that separately, increased-television watching increases cognitive impairment later in life. And separately, so does exercise.
But when combined together, a lack of exercise together with increased television watching doubles one’s risk of cognitive impairment later on.
The researchers of this first study above confirmed this in their conclusion:
“High television viewing and low physical activity in early adulthood were associated with worse midlife executive function and processing speed. This is one of the first studies to demonstrate that these risk behaviors may be critical targets for prevention of cognitive aging even before middle age.”
Does it matter what we watch?
Extending from some of the other cognitive studies in mind, what kind of television we watch should also be a consideration.
The research above quite certainly illustrates the risk of the passive activity involved in watching television. This could mean that one can reduce this passivity by carefully selecting the shows one views.
Certainly, those programs that educate and challenge the mind should produce different results over time. Right?
Maybe. Or maybe not. Computerized brain training programs have shown disappointing results in terms of increasing cognitive skills outside of the tasks they train for. Reviews of the research have shown that while a brain-training course might improve cognitive skills for those tasks included in the course: Outside of those tasks, cognitive improvements are questionable. This also includes what is called fluid intelligence.
But crystallized intelligence – that is, learning new things – does reduce cognitive decline if one utilizes those things learned in the real world. For this reason, learning a new language lessens cognitive impairment later in life – regardless of when the language is learned: And using this second language boosts brain health.
If we expand this logic, one could conclude that watching documentaries or programs that challenge our perspectives and teach us real-life things could allow for a greater use of our cognitive abilities. That is, if we then utilize those new things we learn.
Even so, we’ll still have to get up off the couch and exercise regularly. And even when we’re on the couch, we could be fidgeting.
Hoang TD, Reis J, Zhu N, Jacobs DR Jr, Launer LJ, Whitmer RA, Sidney S, Yaffe K. Effect of Early Adult Patterns of Physical Activity and Television Viewing on Midlife Cognitive Function. JAMA Psychiatry. 2015 Dec 2:1-8. doi: 10.1001/jamapsychiatry.2015.2468.
Keadle SK, Arem H, Moore SC, Sampson JN, Matthews CE. Impact of changes in television viewing time and physical activity on longevity: a prospective cohort study. Int J Behav Nutr Phys Act. 2015 Dec 18;12(1):156. doi: 10.1186/s12966-015-0315-0.
Dunstan DW, Barr ELM, Healy GN, Salmon J, Shaw JE, Balkau B, et al. Television viewing Time and Mortality. The Australian Diabetes, Obesity and Lifestyle Study (AusDiab) Circulation. 2010;121:384–91.
Wijndaele K, Brage S, Besson H, Khaw KT, Sharp SJ, Luben R, Wareham NJ, Ekelund U. Television viewing time independently predicts all-cause and cardiovascular mortality: the EPIC Norfolk study. Int J Epidemiol. 2011 Feb;40(1):150-9. doi: 10.1093/ije/dyq105.
Hambrick DZ. Brain Training Doesn’t Make You Smarter: Scientists doubt claims from brain training companies. Sci Amer. Dec 2, 2014.
Bak TH, Nissan JJ, Allerhand MM, Deary IJ. Does bilingualism influence cognitive aging? Ann Neurol. 2014 Jun;75(6):959-63. doi: 10.1002/ana.24158.