Kids' hostility may increase risk of severe illnesses later

By Marilyn Elias
USA Today

It's the first U.S. research to follow children over time, looking at how their hostility levels affect key heart disease risk factors.

"This clearly shows how psychology affects biology, even at younger ages," says study leader Karen Matthews of the University of Pittsburgh.

Matthews tested 134 youngsters ages 8 to 10 and 15 to 17, then followed them for an average of three years. She looked at how initial hostility levels influenced physical changes, such as high blood pressure and body weight, unhealthy blood fats and "insulin resistance" — ineffective processing of sugar.

The more hostile kids were to start with, the more likely they were to develop at least two of the four unhealthy physical conditions. Those scoring in the top 25 percent on hostility were 50 percent more likely than others to develop at least two of the physical problems. "The insulin resistance and high body-mass index (being overweight) are really driving this," Matthews says. Both have been tied to greater risk for Type 2 diabetes and heart disease.

Hostile kids who go around with chips on their shoulders may not attract many friends, Matthews says, so the overeating could be a "compensation" that leads to a vicious cycle of weight gain and more social rejection.

Hostility levels are about 30 percent genetic, she estimates. But parents can make a big impact by teaching youngsters how to manage anger and solve disputes without seething inside or erupting.

Angry kids are often in a high-stress "fight or flight" mode because they think people are out to get them, says behavioral pediatrician David Schonfeld of the Yale Child Study Center. That feeling prompts surges in cortisol, a stress hormone, which raises blood sugar. "And stressed people often nurture themselves by eating, so it doesn't surprise me that these kids would gain weight, too," he says.

In the "threatening world" scenario adopted by hostile children, the nervous system also increases glucose, says Thomas Boyce, a pediatrician at the University of California-Berkeley. His studies find that preschoolers low on the social totem pole have high cortisol levels. Resentment already might be building in them, he says.

That doesn't mean there's no stopping such attitudes or their harmful physical effects, Schonfeld says. Parents provide models that children imitate, good or ill.

"If every time someone cuts you off you say, 'He thinks he'll get away with that!' and then you speed up to cut the other guy off, your child's learning something," Schonfeld says. "It's important to teach kids that they're not being 'dissed' by every wayward look, and that people's behavior isn't always directed against them."