Last month, the Food and Drug Administration approved one of the medications, Risperdal, to treat bipolar in children. Experts say they expect that move will increase the use of Risperdal and similar drugs for young people.

"We are just inundated with stuff from drug companies, publications, throwaways, that tell us six ways from Sunday that we are failing to diagnose bipolar, said Dr. Gabrielle Carlson, a professor of psychiatry and pediatrics at Stony Brook University School of Medicine on Long Island. "And if you're a parent with a difficult child, you go online, and there's a Web site for bipolar, and you think: 'Thank God I've found a diagnosis. I've found a home."'

Some parents whose children have received the diagnosis say that, with time, the label led to effective treatment.

"It's been a godsend for us," said Kelly Simons, of Montrose, Colo., whose son Brit, 15, was prone to angry outbursts before going on medication. He now is an honor roll student.

Other parents say their children have suffered side effects of drugs for bipolar disorder without seeing much benefit.

Ashley Ocampo, 40, of Tallahassee, Fla., whose 8-year-old son, is being treated for bipolar, said that he had tried several antipsychotic drugs and mood stabilizers and that he had improved.

"He has gained weight," Ocampo said, "to the point where we were struggling find clothes for him. He's had tremors and still has some fine motor problems that he's getting therapy for.

"But he's a fabulous kid," she said, "and I think, I hope, that we're close to finding the right combination of medications to help him."