The number of American children and adolescents treated for bipolar disorder increased 40-fold from 1994 to 2003, researchers are to report onTuesday, in the most comprehensive study to look at the controversialdiagnosis. And experts say the numbers have almost certainly risenfurther in the years since.

Most experts believe the jump reflects the fact that doctors aremore aggressively applying the diagnosis to children, not that thenumber of new cases has gone up. But the magnitude of the increase issurprising to many experts, who say it is likely to intensify a debateover the validity of the diagnosis that has shaken the field of child psychiatry in recent years.

Bipolar disorder is characterized by extreme mood swings and, untilrelatively recently, it was thought to emerge only in adulthood. Some psychiatrists say that the disorder is too often missed in children, and thatincreased awareness — reflected in the increasing use of the diagnosis— is now allowing youngsters who suffer from it to get the treatmentthey need. But others argue that bipolar disorder is overdiagnosed. Theterm, they say, has become a diagnosis du jour, a catch-all now appliedto almost any explosive, aggressive child. Once children are labeled,these experts add, they are treated with powerful psychiatric drugsthat have few proven benefits in children and potentially seriousside-effects, like rapid weight gain.

The spread of the diagnosis has been a boon to drug makers,according to these experts, because treatment typically includesmedications that can be three to five times more expensive than thoseprescribed for other disorders, like depression or anxiety.

“I think the increase shows that the field is maturing when itcomes to recognizing pediatric bipolar disorder, but the tremendouscontroversy reflects the fact that we haven’t matured enough,” said Dr.John March, chief of child and adolescent psychiatry at Duke University’s school of medicine, who was not involved in the research.

“From a developmental point of view, we simply don’t know howaccurately we can diagnose bipolar disorder, or whether those diagnosedat age 5 or 6 or 7 will grow up to be adults with the illness,” hesaid. “The label may or may not reflect reality.”

Most children who qualify for the diagnosis do not go on to developthe classic features of adult bipolar disorder, like mania, researchershave found. They are far more likely to become depressed.

But Dr. Mani Pavuluri, director of the pediatric mood disorders program at the University of Illinois,Chicago, said that label is often better than any of the otherdiagnoses that difficult children often receive. “These are kids thathave rage, anger, bubbling emotions that are just intolerable for them,and it is good that this is finally being recognized as part of asingle disorder,” to better tailor treatment, she said.

In the study, researchers from New York, Maryland and Madridanalyzed data from a National Center for Health Statistics survey ofoffice visits, which focused on doctors in private or group practices.The researchers calculated the number of visits in which doctorsrecorded a diagnosis of bipolar disorder, and found that the numberswent up from roughly 20,000 such diagnoses in 1994 to about 800,000 in2003

“I have been studying trends in mental health services for sometime, and this finding really stands out as one of the most strikingincreases in this short a time,” said Dr. Mark Olfson of the New YorkState Psychiatric Institute at Columbia University,the senior author of the study, which appears in the September issue ofArchives of General Psychiatry, which is to be published Tuesday.

The increase makes bipolar disorder more common among children thanclincial depression, the authors said. The study found thatpsychiatrists made almost 90 percent of the diagnoses, and thattwo-thirds of the young patients were boys. About half the patientsalso had been identified as having other mental difficulties, mostoften attention-deficit disorder.

The treatment given the children almost always included medication.About half received antipsychotic drugs, like Risperdal from Janssen orSeroquel from Astrazeneca, both developed to treat schizophrenia; a third were prescribed so-called mood stabilizers, most often the epilepsy drug Depakote; and antidepressantsand stimulants were also common. Most children were on some combinationof two or more drugs, and about four in 10 received some psychotherapy.

Their regimens were very similar to those of a group of adults withbipolar diagnoses, the study found. “You get the sense looking at thedata that doctors are generalizing from the adult literature andapplying the same principles to children,” Dr. Olfson said.

The rise in bipolar diagnoses in children reflects several factors,experts say. Bipolar symptoms do appear earlier in life than previouslythought, in teenagers and young children who later develop thefull-blown disorder, recent studies suggest. The label also givesdoctors and desperate parents a quick way to try to manage children’srages and outbursts, in an era when long-term psychotherapy andhospital care are less accessible, they say.

In addition, in recent years drug makers and company-sponsoredpsychiatrists have been encouraging doctors look for the disorder, eversince several drugs were approved to treat the disorder in adults. Lastmonth the Food and Drug Administrationapproved one of these medications, Risperdal, to treat bipolar inchildren — which many experts say they expect will escalate the use ofRisperdal and similar drugs in young people.

“We are just inundated with stuff from drug companies, publications,throwaways, that tell us six ways from Sunday that, ‘Omigod, we’remissing bipolar,’ ” said Dr. Gabrielle Carlson, a professor ofpsychiatry and pediatrics at Stony Brook UniversitySchool of Medicine on Long Island. “And if you’re a parent with adifficult child, you go online, and there’s a Web site for bipolar, andyou 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 godsendfor us,” said Kelly Simons, of Montrose, Colo., whose son Brit, 15, wasprone to angry outbursts until given a combination of lithium, amood-stabilizer and Risperdal several years ago. He is now on lithiumalone and he is an honor-roll student.

Others say their children have suffered from side effects of drugs given for bipolar disorder, without getting much benefit.

Ashley Ocampo, 40, of Tallahassee, Fla., the mother of an 8-year-oldboy, Nicholas Ryan, who is being treated for bipolar disorder, saidthat he had tried several antipsychotic drugs and mood stabilizers, andthat he had been better lately.

But, she said in an interview, “He has gained weight, to the pointwhere we were struggling find clothes for him; he’s had tremors, andstill has some fine motor problems that he’s getting therapy for.”

She added, “But he’s a fabulous kid, and I think, I hope, that we’reclose to finding the right combination of medications to help him.”