Previous Findings Unclear
A limited number of studies had already explored the TV-cognition link in older people. A European study included subjects aged 65 to 84. The researchers concluded that TV viewing and mild cognitive impairment were linked. A US study found watching soap operas and talk shows was associated with poorer cognition in older women. Another found television viewing among the middle-aged increased the risk of developing Alzheimer's. But because sitting for protracted periods is also associated with dementia, it's not clear from these studies what is being measured -- watching TV or sitting. And the results might also suggest that people who spend a lot of time in front of the tube don’t have much on the ball to start with. So psychologists from University College London carried out a far more robust study than anything conducted so far. They wanted to know if TV watching in older adults harms cognitive ability, and if so, whether this is regardless of other possible influences. To do this, they looked at data from the English Longitudinal Study of Ageing. This is a comprehensive long-term health and lifestyle resource that gathers information on people over 50 living in England. The study included 3,662 dementia-free men and women with an average age of 67. Besides filling out a questionnaire concerning how much TV they watched, they also underwent tests of verbal memory and semantic fluency (basically, the ability to recall and express some simple information). To assess verbal memory, ten words are presented to the participants by a taped voice every few seconds. They have to recall the words immediately after hearing them and then again several minutes later. In between, they have to complete other cognitive tasks. For the semantic fluency test, the subjects had to name as many animals as possible in one minute. These tests were chosen because they've been shown to predict cognitive decline. In their analysis, the researchers took into account not only activity levels, but also age, gender, marital status, employment, education, income, health conditions, newspaper reading and internet use.Too Much TV Doubles Memory Loss
Six years later, after the tests were repeated, the researchers found those who watched TV for more than 3½ hours a day saw their verbal memory decline by 8 to 10 percent compared to 4 - 5 percent in those who watched less. Semantic fluency was not significantly affected. In their paper, the study authors, Dr. Daisy Fancourt and Professor Andrew Steptoe, explained their finding based on previously conducted lab experiments that measured brain activity and specifically explored the effects of TV viewing on cognition. They write that television "leads to a more alert but less focused brain," and is also the most passive way of receiving fast-paced changes in images, sounds and action. This "alert-passive interaction" explains why the experimenters found, on the one hand, a more activated brain, and on the other, "poor short and long-term memory following viewing, and low brain-wave activity." The researchers believe this is the most likely explanation for cognitive loss, because other screen activities such as gaming or internet use, which are more interactive, have been shown to improve cognition in older people.Violent Programming May Make You Stupid
Another possible explanation, they suggest, is due to programs that depict "graphic scenes, violence, or the creation of suspense." These lead to chronic stress, which is known to have negative consequences for brain health. Finally, they suggested the results of their study could have a very simple explanation. If people weren't watching a lot of TV, they might otherwise be engaged in activities that are cognitively beneficial like reading or socializing. A number of experts were asked for their opinion of the study. They all agreed it was well conducted and scientifically sound, but while it provides some evidence of cause and effect, it’s not final proof that excessive TV viewing lowers cognition. Professor Tara Spires-Jones, a leading neuroscientist from the University of Edinburgh, Scotland, said, "... more work will need to be done to fully understand whether watching television is truly the culprit in contributing to memory decline as we age. "Having said that, the evidence that remaining active and engaged is good for cognition during aging is overwhelming, so being active instead of watching TV is likely to be good for us all.”