CHICAGO - Strong warnings by the U.S. Food and Drug Administration about suicide risks linked to antidepressant use in children and young adults have had a spillover effect on depression care in older adults, researchers said on Monday.

They said the warnings resulted in a lasting decline in depression diagnosis and treatment, even for older adults, and urged the FDA to revise its policy.

Policy actions are required to counter the unintended consequences of reduced depression treatment, Anne Libby of the University of Colorado and her colleagues wrote in the Archives of General Psychiatry.

U.S. and European regulators sent out a series of public health warnings on use of antidepressant drugs beginning in 2003 after clinical trials showed they increased the risk of suicidal thoughts and behaviors in children and teens.

In February 2005, the FDA added its strongest warning, a so-called black box, on the use of all antidepressants in children and teens to draw attention to the possible risks of these medications. In May 2007, it extended the warnings to young adults aged 18 to 24.

Many psychiatrists have criticized the warnings, saying they scare people away from effective treatment for depression, the leading cause of suicide.

And recent studies have suggested the drug warnings triggered an 8 percent rise in suicide among youth and teens in 2004, the biggest one-year gain in 15 years.

To understand the full impact of the warnings, Libby and colleagues analyzed managed care claims data from July 1999 through June 2007.

While they saw steady increases in the rate of depression diagnoses in each group between 1999 through 2004, the rate of diagnoses in children and teens fell sharply starting in 2004.

They found primary care doctors specifically diagnosed fewer cases of depression, with a 44 percent lower rate among children and adolescents, 37 percent lower among young adults and 29 percent lower among adults.

Doctors did not, apparently, turn to other drugs, including older antidepressants and anxiety drugs, the researchers said. Nor did they, evidently, offer non-drug treatments such as cognitive behavioral therapy, which aims at changing the way patients think.

Use of antidepressants called selective serotonin reuptake inhibitors or SSRIs, which affect a message-carrying brain chemical called serotonin, decreased in all three groups.

While the warnings achieved the intended effect of reducing antidepressant use in young people, Libby and colleagues said they had a persistent, unintended effect on depression diagnosis and treatment, and urged the agency to revise its policy.

Because the team looked at health insurance claims data, they could not address why doctors diagnosed fewer cases of depression. We don't know why. What we can say is that the warnings definitely changed behavior, Libby said in a telephone interview.

She said it may be that patients are not seeking treatment or that doctors are not making diagnoses because they do not feel they have good treatments to offer.

The shortage of psychiatrists, especially child and adolescent psychiatrists in the community, is felt by every clinician who has ever been asked for help by desperate parents with a suicidal child, they wrote.

We appreciate these efforts to look at possible impacts of our labeling changes, and we continue to gather data and assess this situation, Sandy Walsh, a spokeswoman for the FDA, said in an e-mail.

Walsh said the trends being seen are a concern but noted the agency also tracks other data, including suicide data from Centers for Disease Control and Prevention.

(Additional reporting by Lisa Richwine in Washington; Editing by Maggie Fox and Paul Simao)

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