Over the past few decades, there's been an amazing increase in the number of children diagnosed with autism. Some experts think this is due to broader diagnostic criteria for autism. Some point to vastly increased services for autistic children. Others think that something in the environment is triggering an autism epidemic.
It occurred to Cornell University management professor Michael Waldman, Ph.D., that the increase in autism cases came at the same time as increased opportunities for very young children to watch TV. Could it be, he wondered, that the explosion in children's TV programming, DVDs, VCRs, and video/computer games is behind the explosion in autism diagnoses?
Waldman asked his colleagues in the medical world to look at the issue. Nobody would. So he assembled a research team and did the study himself — using tools more often seen in economic studies than in medical studies. The results bolstered his suspicions.
"We are not claiming that we have definitive evidence. But we have evidence that is awfully suggestive of a link between TV watching and autism," Waldman tells WebMD. "Someone should nail this down one way or the other."
Waldman will present the study at this week's National Bureau of Economic Research health economics conference.
Autism is usually diagnosed when a child is about 3 years old. Any effect of TV watching would have to happen before that age. But few studies, Waldman found, have compiled statistics on the TV habits of U.S. toddlers.
But there are statistics, compiled by the U.S. Bureau of Labor Statistics, on when families watch TV and how much TV they watch. These statistics show that toddlers watch more television when it's raining outside than when it isn't raining.
Waldman and colleagues then looked at county-by-county autism rates in California, Oregon, and Washington. All three states have huge regional variations in annual rainfall. Sure enough, Waldman found that autism rates tended to be higher in the rainiest counties.
"We ran the tests a number of different ways, and basically every way we run it, we get the same thing. If it rains more, autism goes up. If it rains less, autism goes down," Waldman says. "That is a fine theory by itself, but still one can't be sure it is TV and not some other indoor toxin that is to blame."
So the researchers did a second test: They looked at the percentage of houses that subscribed to cable television in California and Pennsylvania. Cable television, Waldman reasoned, was linked not only to more TV watching, but also to the availability of more programming for very young children.
Sure enough, they found that areas with the most cable TV subscribers had the most autistic children. "Our view is there is no obvious thing correlated with both rain and cable-TV access except television viewing," Waldman says.
Until more direct studies confirm or disprove this conclusion, Waldman and colleagues recommend that parents follow the American Academy of Pediatricians' recommendation of no TV before age 2, and no more than an hour or two of TV a day for older children.
Child development expert Leslie Rubin, M.D., finds Waldman's study interesting. But he does not think it proves a link between autism and television viewing. Rubin is director of developmental pediatrics at Emory University and director of the center for developmental medicine at the Marcus Institute, Atlanta.
"They are looking at trends in the diagnosis of autism more than the actual prevalence of autism itself," Rubin tells WebMD. "They correlate these diagnostic trends with rain and county, and at another level with the proliferation of cable TV and stuff like VCRs and DVDs and computer games. They all happened at the same time, but I can't see that one is the cause of the other."
This doesn't mean that Rubin rejects Waldman's idea that TV can trigger autism.
"TV viewing might be associated with autism if a child has that tendency and is not forced or coaxed or encouraged to engage in social interactions but instead is allowed to sit in front of a television," he says. "The whole goal of autism treatment is to encourage social interactions. We know that makes the single biggest difference in children's outcomes — how they relate to others. So if they watch TV instead of interacting, they are going to get more withdrawn."
Like Waldman, Rubin says Americans — including medical researchers — don't pay enough attention to what television does to kids. "We use TV for babysitting, as a substitute for social interactions, as the sole form of entertainment for children and families," he says. "Instead of kids going out to socialize, they stay home and watch TV. So if they have tendencies toward autism, these would be accentuated by the absorption of TV instead of being challenged by social interactions."
Obviously, Rubin isn't just talking about kids with autism. He's talking about all of our kids — and all of us.
"Social experiences are important for kids as they grow up. Social experiences shape a person's life," he says. "If children watch TV for most of their lives, I think there will be some sort of negative impact. This may well be associated with some diagnostic condition."
By Daniel DeNoon
Reviewed by Louise Chang, M.D