The study, published in the journal Pediatrics, is not the first to link behavioral issues to so-called sleep-disordered breathing -- where children chronically snore, mouth-breathe or seem to stop breathing for several seconds at a time as they sleep (what doctors call "apnea").

"We didn't invent the association," noted lead researcher Karen Bonuck, of the Albert Einstein College of Medicine in New York.

But, she said, this is the largest study yet to look at the question, following more than 13,000 children from infancy to the age of seven.

Of those kids, 45 percent remained free of nighttime breathing problems, based on parents' reports. The rest had symptoms at some point during infancy or early childhood.

Eight percent of the children fell into what the researchers dubbed the "worst case" group; they had breathing symptoms that "peaked" between the ages of two and three, and then persisted.

Overall, Bonuck's team found, children with sleep-disordered breathing at any time were more likely to develop symptoms of behavioral or emotional disorders -- like attention deficit hyperactivity disorder (ADHD) or anxiety -- by age seven.

About 13.5 percent had such symptoms at age seven, versus just over eight percent of kids who'd been free of sleep-disordered breathing.

And the biggest risk was seen in the worst-case group. By age 7, nearly 18 percent of those kids had possible behavioral or emotional disorders.

The researchers can't say for sure whether all of those children had outright disorders, such as ADHD. Their results are based on a screening questionnaire given to parents. And the children would have to be further evaluated to get a diagnosis, Bonuck explained.

What's more, it's not certain that the breathing problems are directly to blame.

But, Bonuck said, the researchers did factor in a range of variables that could help account for the link -- like parents' income and education, race, birthweight and whether moms smoked during pregnancy.

"Even considering all those variables, overall, sleep-disordered breathing seemed to have the strongest effect," Bonuck said.

Among the "worst case" kids, for example, sleep-disordered breathing was linked to a 72 percent increase in the risk of behavioral and emotional symptoms at age seven -- even with other factors considered.

"This provides strong evidence that the (breathing) symptoms we looked at could promote these behavioral and emotional symptoms," Bonuck said.

Still, she stressed, no one is saying sleep-disordered breathing is the whole story. "Certainly, emotional and behavioral disorders are multi-factorial," Bonuck said.

As for parents, she advised "not panicking."

"But parents can pay attention to their child's breathing," Bonuck said. "And if they have a concern, they should ask their pediatrician about it."

"What (the study) found is intuitively what we'd expect to see," said Dr. Sanjeev V. Kothare, interim medical director of the Center for Pediatric Sleep Disorders at Children's Hospital Boston.

Kothare, who was not involved in the study, agreed that parents should talk to their pediatrician if they notice their child is snoring and has other tell-tale symptoms.

Those, he said, may include not only mouth-breathing and episodes of apnea, but also "daytime behaviors" like sleepiness or, on the other end of the spectrum, hyperactivity.

Kothare noted that the American Academy of Pediatrics (AAP) already recommends that pediatricians should screen all children for snoring and, if needed, refer them to a sleep center for further evaluation.

So it's important, Kothare said, for parents to be aware of kids' snoring.

If a child does have sleep-disordered breathing, there are a number of potential treatments. In many kids, especially 3- to 6-year-olds, the problem is caused by enlarged tonsils or adenoids, and removing the tissue can improve nighttime breathing -- as well as daytime symptoms, Kothare noted.

For other children, excess pounds feed the nighttime breathing problems, and most will improve if they shed the extra weight, according to the AAP.

Another treatment option is continuous positive airway pressure (CPAP), where children wear a special mask that delivers steady air pressure through the nose while they sleep.

SOURCE: bit.ly/x5N27K Pediatrics, online March 5, 2012.

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