Researchers say they've shown for the first time that treating a mother's depression can help prevent depression and anxiety disorders in her child, a provocative finding with potentially big public health implications.

The study was small, but the researchers and other experts called it convincing and said it illustrates how important a parent's well-being is to a child.

"It's a very dramatic and important finding," said co-author Dr. A. John Rush, a psychiatry professor at the University of Texas Southwestern Medical Center.

Depression runs in families and has a strong genetic component, but environmental factors can trigger it. The study results indicate that for children of depressed mothers, that trigger is sometimes their mothers' illness acting up, said lead author Myrna Weissman, a researcher at Columbia University and New York Psychiatric Institute.

Effective treatment for mothers could mean their children might avoid the need for prescription antidepressants, the researchers said.

"Depressed parents should be treated vigorously. It's a two-fer — the impact is not only on them but it's also on their children," Weissman said.

In the study, those children whose mothers' depression disappeared during three months of treatment were much less likely to be diagnosed with depression, anxiety or behavior problems than those whose mothers did not improve.

The results are "very plausible and very convincing and very useful," said Dr. Nada Stotland, vice president of the American Psychiatric Association and a psychiatry professor at Rush Medical College in Chicago.

"Our society gives a lot of lip service to how important mothers are but in fact we don't always appreciate just how profound their effects on their children are," said Stotland, who was not involved in the study.

While mothers often tend to put their own needs last, this research "is a good argument for them to take care of themselves first," she said. "It's a little like putting your own oxygen mask on first on the airplane. If you can't breathe, you can't help anybody."

The study appears in Wednesday's Journal of the American Medical Association and involved 114 depressed women assessed after three months of treatment. Of the 114 children participants, aged 11 to 12 on average, 68 had no psychiatric disorder when their mothers began treatment.

Thirty-eight women went into complete remission from depression during treatment, which for most was Forest Laboratories' antidepressant Celexa.

Forest supplied the drug and several study authors have financial ties to other antidepressant makers, but the study was funded by grants from the National Institute of Mental Health.

Among children with psychiatric problems, the remission rate was 33 percent after three months for those whose mothers recovered versus 12 percent among those whose mothers did not.

Among children without psychiatric problems at the outset, all whose mothers recovered also remained healthy, whereas 17 percent of those whose mothers remained depressed were diagnosed with psychiatric problems by the study's end.

Weissman said similar results likely would occur with different drugs and/or psychotherapy. She also said similar results likely would be found with depressed fathers, although none were studied.

Dr. Peter Robbins, a Fairfax, Va. psychiatrist, said he's seen similar results in his pediatric practice, and not just with depression.

For example, children with attention deficit/hyperactivity disorder often have similarly afflicted parents. Getting treatment for the parents, father or mother, yields improvement in the children's symptoms, he said.

The study underscores "that taking care of the kid means taking care of the whole family," Robbins said.

Here are some details about women and depression:

--Depression hits more than 19 million U.S. adults each year, including about 12 million women.

--Compared with men, women face double the risk of being diagnosed with clinical depression.

--About 1 in 8 U.S. women will be diagnosed with depression during their lifetime.

--Depression occurs most often during women's childbearing years, ages 25 to 44.

--Depression in women can include postpartum depression, which affects about 10 percent to 15 percent of all new mothers.

--Fewer than half the women who experience depression seek treatment.