Seriously depressed adolescents recover most rapidly if they take antidepressants and get a structured type of therapy, rather than one or the other, suggests a landmark government study out this month.

More than four out of five had greatly improved, with most no longer depressed after 36 weeks of treatment, whether they had therapy, medication or both.

"It's a good-news story," says John March, chief of child and adolescent psychiatry at Duke University Medical Center, who led the study on 327 kids, ages 12 to 17, with moderate to severe depression. It's the largest and longest study ever done on depression treatments for adolescents. About 5 percent of U.S. adolescents are affected by depression, an estimated 1.3 million, according to national surveys.

After 36 weeks, recovery rates were similar for those only in counseling, only taking Prozac or treated with medication and therapy, shows the study in the Archives of General Psychiatry. But depression lifted sooner for the "combination" group that took drugs and participated in cognitive behavioral therapy, which teaches stress relief and coping skills, March says.

A key safety concern about using Prozac without therapy was that the medication-only children were about twice as likely as the other children to be suicidal — either thinking about killing themselves or trying to, March says.

The Food and Drug Administration ordered black boxes for antidepressants in 2004, saying the medications slightly increased the risk of suicidal behavior in children. Because cognitive behavior therapy teaches stress management, it may offset that higher risk, March speculates.

Parents of seriously depressed kids shouldn't necessarily reject antidepressants because therapy proved as effective after nine months, says Benedetto Vitiello, chief of the child and adolescent treatment and research branch at the National Institute of Mental Health. "Nine months is a long time in the life of a child," Vitiello says. "He can fall behind in school, it can derail a lot of activities and social development."

Also, therapy is not widely available for kids, says Sheila Marcus, director of child and adolescent psychiatry at University of Michigan Medical School. "There's a tremendous shortage of therapists trained in (cognitive behavior therapy)," she says. The new study underscores that "the vast majority of depressed children in this country don't get optimal treatment."

Suicide rates for U.S. children rose 14 percent in 2004, and some have linked that spike to decreases in antidepressant prescriptions for kids after the FDA put a black box on the drugs that year. But suicide rates for 2005, covering the period after black boxes, won't be out until next summer.

"If it's the beginning of a trend in more suicides tied to fewer prescriptions, then there's reason for concern," says psychiatrist Richard Friedman of Weill Cornell Medical College in New York. "It would be terrible if people lost the bigger picture, that some children need the drugs, as this study proves."