Researchers say TV is not to blame for ADHD

CHILD DEVELOPMENT
Television's critics often blame the ''electronic babysitter" for contributing to a host of children's problems, from obesity to sloth to violent behavior. But when a pair of Texas researchers saw a 2004 study blaming hyperactivity on excessive TV watching, they couldn't remain silent. Tara Stevens and Miriam Mulsow felt that the research leaped to conclusions based on an overly broad definition of attention deficit/hyperactivity disorder, or ADHD. Now, after a review of the TV-watching habits of 5,000 kindergartners and first-graders, the two say they see no connection between TV exposure and ADHD. The Texas Tech University researchers said 5-year-olds whose parents limited television watching or spent more time with them were just as likely to be diagnosed with ADHD a year later as children who watched more TV and spent less time with parents. The earlier study had found that heavy TV watching between the ages of 1 and 3 increased the risk of attention problems by age 7, but Muslow said the researchers defined attention problems to include symptoms not normally associated with ADHD.

BOTTOM LINE: Even if TV does not shorten children's attention span, the Texas researchers say there are still good reasons to limit children's viewing. ''Probably the more important issue is making sure that TV doesn't keep the kids from doing things they ought to do," said Mulsow.

CAUTIONS: Neither the Texas study nor the earlier research were based on direct examinations of children, instead relying on national databases that keep track of kids' lifestyle and development. As a result, all the findings are based on analysis of other people's observations.

WHAT'S NEXT: Stevens and Mulsow call for a study that follows children over time, tracking the amount and type of TV watched and who is diagnosed with ADHD.

WHERE TO FIND IT: Pediatrics, March 2006

SCOTT ALLEN

ARCHEOLOGY

Easter Island's population may be younger than thought

When Western explorers discovered the South Pacific's Easter Island in the 18th century, they found a starving population living among mysterious stone monuments on a deforested island. Ever since, there has been speculation about the origins of the island civilization and the cause of its collapse. For years, archaeologists assumed that the first Polynesian settlers arrived on the island during the 8th century, building a society that flourished for centuries. Then, the thinking went, the islanders suddenly started building their immense stone statues -- a task that used up the island's limited resources, sparking deforestation, erosion, and widespread starvation. But a new study calls this timeline into question. The latest radiocarbon dating of soil samples believed to contain evidence of the island's first settlement indicates that the earliest traces of civilization date only to the 13th century, just before the statues starting going up. The find means that humans likely arrived on the island during the 13th century, setting ecological catastrophe into motion soon after. ''There's no longer a long period when people would have been on the island and had no impact," said Terry Hunt, an archaeologist at the University of Hawaii at Manoa and lead author of the study.

BOTTOM LINE: Polynesians likely settled Easter Island during the 13th century and began building statues and altering the island's environment nearly immediately.

CAUTIONS: Because the study calls into question many previously obtained radiocarbon dates that Hunt and his team analyzed and rejected because of problems in methodology, more dating is needed to confirm the new chronology.

WHAT'S NEXT: The shifted chronology suggests a host of follow-up studies to better characterize the relationship between the island's human, plant, and animal inhabitants. The latest finding ''shakes our confidence in what we actually know about the island," Hunt said. ''What else is going to surprise us?"

WHERE TO FIND IT: Science, published online March 9, 2006

EMILY ANTHES

BREAST CANCER

One in 10 tumors diagnosed would never pose health risk

Screening women for breast cancer by mammography saves lives by detecting tumors in their early stages, but this strategy comes at a price. Mammography is so sensitive that it can lead to overdiagnosis, causing people to undergo difficult cancer treatments for slow-growing tumors that would not have caused problems within their lifetimes. A research team lead by Sophia Zackrisson at Malmo University Hospital in Sweden has found that one in 10 breast cancers found in women between the ages of 55 and 69 may not end up being lethal. But because it is still impossible to determine which tumors will have significant consequences, doctors believe it's better to overdiagnose and overtreat than to miss potentially lethal tumors.

BOTTOM LINE: Although the benefits of mammography outweigh the risks, women should be aware that there is a chance they will be unnecessarily diagnosed with cancer.

CAUTIONS: The Swedish researchers estimated the rate of overdiagnosis by following women 15 years after they participated in a mammography screening trial. However, mammography equipment used in clinics today is more sensitive than the machines used in this study, so the current rate of overdiagnosis is likely much higher.

WHAT'S NEXT: Zackrisson's group is interested in performing larger follow-up studies to include younger women. Women diagnosed with breast cancer at a younger age have more time to develop problems from slow-growing tumors, which would increase the importance of mammography and make overdiagnosis less of a concern.

WHERE TO FIND IT: British Medical Journal, March 3, 2006, free online at http://bmj.bmjjournals.com/cgi/rapidpdf/bmj.38764.572569.7C

ZARA HERSKOVITS