Researchers thought a spike in youth suicides in 2004 may have been an anomaly. But the new study found the increase in suicides continued during 2005.

Looking at suicide trends among youngsters over a 15-year period, Jeff Bridge, from Nationwide Children's Hospital in Columbus, Ohio, found the rates of suicide among youths aged 10 to 19 were higher in 2004 and 2005 than would have been expected, based on suicide rate trends from 1996 to 2003.

"This is significant, because pediatric suicide rates in the U.S. had been declining steadily for a decade until 2004, when the suicide rate among U.S. youth younger than 20 years of age increased by 18 percent, the largest single-year increase in the past 15 years," said Bridge, an investigator in the Center for Innovation in Pediatric Practice.

"We now need to consider the possibility that this increase is an indicator of an emerging public health crisis. Studies to identify causal factors are important next steps," he added.

Bridge, whose findings were published in the Sept. 3 issue of the Journal of the American Medical Association, said several factors could be contributing to the increase in youth suicides. They include the influence of Internet social networking sites; an increase in the suicide rate among U.S. troops returning from Iraq and Afghanistan; and higher rates of untreated or undiagnosed depression.

One possible explanation for the increase could be that antidepressant use among children has been the subject of intense controversy in recent years, making doctors and parents more reluctant to use them.

In October 2003, the U.S. Food and Drug Administration issued a public health advisory, warning of an increased risk of suicide attempts or suicide-related behavior among children and teens taking antidepressants called SSRIs, or selective serotonin reuptake inhibitors.

One year later, the FDA directed manufacturers of antidepressants to revise their labeling to include a "black-box" warning. The warning alerts health-care providers about an increased risk of suicide and suicidal thoughts in children and teens.

This warning may have had a dampening effect on the drugs' use among children. A recent study found that the number of U.S. children being prescribed antidepressants has dropped since the warnings. Some experts have said this trend could be worrisome if it means that young patients who might benefit from SSRIs aren't getting them.

In a previous study, Bridge found that treating children with antidepressants was beneficial. "Our study shows that, at least in the short-term, treatment benefits appear to outweigh the risks," he said.

Diana Zuckerman, president of the National Research Center for Women & Families, agreed that the increase in youth suicides is now a trend, but the reasons for it are multi-faceted.

The increase among older teens may be due, in part, to the languishing economy. "When the economy is bad, and jobs are harder to find, it's a tough time for kids who are trying to get a job," she said.

It's also harder to get into college and afford it, Zuckerman said. "So, for kids who are college-bound, there are those stressors," she said.

Zuckerman also thinks that untreated depression may play a role in the increase suicide rate.

But overall, she thinks that children are more isolated, even from their families, than ever before.

"Kids and family members are spending more and more time apart," she said. "Apart might mean being on the computer. Kids and their families are not watching TV together, they're not eating meals together, they are not talking to each other nearly as much."

"There is a lot of data that shows when families don't eat together, kids get into trouble. And trouble means drug use, alcohol use, sex and suicide," she said. "Parents need to be more involved in the decision-making process about what their kids are doing."