Tots' TV time tied to asthma risk

Consumer Reports News: March 10, 2009 11:08 AM

You might laugh if you saw our TV. Inside a spacious cabinet sits a tiny 13-incher from the early '90s— the first major purchase I made after college. Needless to say, we're not a family of big TV watchers (pun intended). But that doesn't mean my son hasn't occasionally spent long stretches glued to our smallish screen. Typically I regret these TV binges, as he's generally out of sorts afterward, with what's best described as a TV hangover. A surefire cure? Having him romp around the backyard for 20 minutes or so after.

For my son, the immediate effects of watching lots of TV are obvious. But what, if any, are the long-term effects, especially if a young child watches hours of TV every day? This is an area of keen interest for parents and researchers, especially in relation to how TV viewing affects brain development and the risk of childhood obesity. A new study* suggests another area of concern: lung development and asthma.

In the study, researchers identified more than 3,000 children who had no symptoms of wheezing at age three-and-a-half, and then followed them for eight years. Their parents were interviewed annually about any wheezing and whether their child had been diagnosed with asthma. They were also asked about their child's television viewing from age three-and-a-half. (They were not quizzed about use of personal computers or game consoles, as these were not widespread when the study began in the mid-'90s.)

By age 11 1/2, 6 percent of the children had been diagnosed with asthma overall. But within this group, the risk varied considerably depending on how much TV the children had watched at a young age. Those who had watched more than two hours a day at age three-and-a-half had double the risk of asthma eight years later, compared with children who had watched less. These findings held up even after researchers took into account several other things that could have affected the children's risk, such as being very overweight or having a mother who smoked while pregnant.

However, this doesn't mean that TV watching actually triggers asthma. Instead, researchers think watching a lot of TV signifies a less active lifestyle, which may make asthma more likely. Other studies, they point out, have suggested that breathing patterns associated with inactive behaviors like TV viewing might lead to changes in how young lungs develop.

This study wasn't perfect, as the researchers relied on parents to estimate their child's TV viewing and didn't consider some things known to influence asthma risk, such as whether family members smoke around a child. But it does raise important questions about how increased periods of inactivity might affect a young child's lungs. And as most parents will attest, TV viewing is one of the few things that can make otherwise active children sit still for extended lengths of time.

What you need to know. Sitting glued to the TV for hours every day isn't the healthiest of habits for anyone, but especially not for young children, who need lots of physical activity to grow up fit and strong. So how much TV is too much? Studies don't yet provide a clear answer. But as a general guide, the American Academy of Pediatrics* recommends that children under age two not watch any TV, and that older kids be limited to one to two hours a day (even less if they also use other entertainment media).

Sophie Ramsey, patient editor, BMJ Group has partnered with The BMJ Group to monitor the latest medical research and assess the evidence to help you decide which news you should use. 

Read more on asthma symptoms in children, find out what could be triggering your child's asthma, and see our Treatment Ratings (subscribers only) for effective ways to relieve symptoms and prevent attacks.

*links to PDF

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