In recent years, there's been a dramatic increase in the number of children being diagnosed with serious psychiatric disorders and prescribed medications that are just beginning to be tested in children. The drugs can cause serious side effects, and virtually nothing is known about their long-term impact. "It's really to some extent an experiment, trying medications in these children of this age," child psychiatrist Dr. Patrick Bacon tells FRONTLINE. "It's a gamble. And I tell parents there's no way to know what's going to work."

In The Medicated Child, FRONTLINE producer Marcela Gaviria confronts psychiatrists, researchers and government regulators about the risks, benefits and many questions surrounding prescription drugs for troubled children. The biggest current controversy surrounds the diagnosis of bipolar disorder. Formerly called manic depression, bipolar disorder was long believed to exist only in adults. But in the mid-1990s, bipolar in children began to be diagnosed at much higher rates, sometimes in kids as young as 4 years old. "The rates of bipolar diagnoses in children have increased markedly in many communities over the last five to seven years," says Dr. Steven Hyman, a former director of the National Institute of Mental Health. "I think the real question is, are those diagnoses right? And in truth, I don't think we yet know the answer."

Like many of the 1 million children now diagnosed with bipolar, 5-year-old Jacob Solomon was initially believed to suffer from an attention deficit disorder. His parents reluctantly started him on Ritalin, but over the next five years, Jacob would be put on one drug after another. "It all started to feel out of control," Jacob's father, Ron, told FRONTLINE. "Nobody ever said we can work with this through therapy and things like that. Everywhere we looked it was, 'Take meds, take meds, take meds.'"

Over the years, Jacob's multiple medications have helped improve his mood, but they've also left him with a severe tic in his neck which doctors are having trouble fully explaining. "We're dealing with developing minds and brains, and medications have a whole different impact in the young developing child than they do in an adult," says Dr. Marianne Wamboldt, the chief of psychiatry at Denver Children's Hospital. "We don't understand that impact very well. That's where we're still in the Dark Ages."

DJ Koontz was diagnosed with bipolar at 4 years old, after his temper tantrums became more frequent and explosive. He was recently prescribed powerful antipsychotic drugs. "It is a little worrisome to me because he is so young," says DJ's mother, Christine. "If he didn't take it, though, I don't know if we could function as a family. It's almost a do-or-die situation over here." DJ's medicines seem to be helping him in the short run, but the longer-term outlook is still uncertain. "What's not really clear is whether many of the kids who are called bipolar have anything that's related to this very well-studied disorder in adults," says Dr. Thomas Insel, the director of the National Institute of Mental Health. "It's not clear that people with that adult illness started with what we're now calling bipolar in children. Nor is it clear that the kids who have this disorder are going to grow up to have what we used to call manic-depressive illness in adulthood."

While some urge caution when it comes to bipolar in children, FRONTLINE talks with others who argue that we should intervene with drug treatments at even younger ages for children genetically predisposed to the disorder. "The theory is that if you get in early, before the first full mood episode, then perhaps we can delay the onset to full mania," says Dr. Kiki Chang of Stanford University. "And if that's the case, perhaps finding the right medication early on can protect a brain so that these children never do progress to full bipolar disorder."