More than six million children in the US – some as young as two – take behaviour modifying drugs. FRONTLINE questions how and why these children are being diagnosed, whether the drugs are safe, and if the real epidemic is the diagnosis itself.

What were once dismissed as temper tantrums in children are now seen as evidence of bipolar disorder – manic depression. Increasingly, children are being prescribed powerful drugs that some say have yet to be fully tested for side-effects.

Like many 'bipolar' children, five-year-old Jacob Solomon was originally diagnosed with attention deficit disorder. Over the years he was given one drug after another. "Nobody ever said we can work with this through therapy," says his father, Ron. "Everywhere it was, 'Take meds, take meds.'"

Other parents, however, seem more convinced of the value of drugging their children, while Dr Kiki Chang of Stanford University suggests catching the symptoms early may actually prevent the child from developing full bipolar disorder in later life.