New government figures show a surprising increase in youth suicides after a decade of decline, and some mental health experts think a drop in use of antidepressant drugs may be to blame.

Suicides climbed 18 percent from 2003 to 2004 for Americans under age 20, from 1,737 to 1,985 deaths. Most suicides occurred in older teens, according to the data — the most current to date from the federal Centers for Disease Control and Prevention.

By contrast, the suicide rate among 15- to 19-year-olds fell in previous years, from about 11 per 100,000 in 1990 to 7.3 per 100,000 in 2003.

Suicides were the only cause of death that increased for children through age 19 from 2003-04, according to a CDC report released Monday.

"This is very disturbing news," said Dr. David Fassler, a University of Vermont psychiatry professor.

He noted that the increase coincided with regulatory action by the U.S. Food and Drug Administration that led to a black box warning on prescription packages cautioning that antidepressants could cause suicidal behavior in children.

Fassler testified at FDA hearings on antidepressants during 2003 and 2004 and urged caution about implementing black box warnings. The agency ordered the warnings in October 2004 and they began to appear on drug labels about six months later.

Psychologist David Shern, president of Mental Health America, called the new data "a disturbing reversal of progress."

Other research has linked certain antidepressants with decreasing suicide rates, Shern said, adding, "We must therefore wonder if the FDA's actions and the subsequent decrease in access to these antidepressants in fact have caused an increase in youth suicide."

The advocacy group receives funding from makers of antidepressants, government agencies and private donations.

The suicide data are in a report on vital statistics published in February's Pediatrics.

Antidepressant use among children decreased during the same time period. Data from Verispan show 3 million antidepressant prescriptions were written for kids through age 12 in 2004, down 6.8 percent from 2003. Among 13- to 19-year-olds, the number dropped less than 1 percent to 8.11 million in 2004. Steeper declines in both age groups occurred in 2005, according to the prescription tracking firm.

The suicide data are preliminary and don't show whether suicides might have been concentrated in one region or among one gender or ethnic group, said the CDC's Dr. Alexander Crosby.

"It's something that we want to look a little bit closer into," Crosby said. "It's probably too early to say" if declining use of antidepressants had anything to do with it, he said,

The CDC is expected to issue a more thorough report on the data in a month or two.

The data are concerning, but it's too soon to know if they're anything more than a statistical blip, said Dr. John March, a Duke University psychiatry professor. He led landmark National Institute of Mental Health research linking antidepressant use with an increased risk for suicidal behavior, but also showing that getting psychotherapy at the same time canceled out that risk.

Some mental health experts believe suicide prevention programs and effective use of treatment including drugs and therapy contributed to the decline in suicides that occurred in the 1990s.

Funding cuts for school-based suicide prevention programs might have contributed to the apparent rise noted in the new CDC report, said Emory University psychologist Nadine Kaslow. But the rise might not indicate a nationwide trend and needs to be investigated, she said.

"It's definitely concerning" but will need to be followed to see whether increases occurred in subsequent years, Kaslow said.