The consequences of misdiagnosis are not trivial. Stimulant drugs such as Ritalin and Adderall, which are commonly used to treat ADHD, are not only ineffective for bipolar disorder but may worsen its symptoms or even trigger manic episodes. Meanwhile these drugs may produce side effects such as weight loss, insomnia and nervousness. On the other hand, a child with ADHD who is mistakenly diagnosed with bipolar disorder will usually be prescribed one or more of several medications, including lithium, anticonvulsants such as Depakote or Lamictal, or atypical antipsychotics (Abilify, Zyprexa). All these drugs are ineffective for ADHD and can cause side effects such as weight gain and involuntary movements. Rare but more serious problems such as seizures (from lithium) can show up when the dosage is too high.
To reduce the problems of overlap and overdiagnosis, the authors of the DSM-5, to be published in 2013, have proposed adding a category called disruptive mood dysregulation disorder [see “Redefining Mental Illness,” by Ferris Jabr; Scientific American Mind, May/June 2012]. Symptoms of this illness would include frequent temper outbursts and chronically irritable, angry or sad moods. This addition could provide a diagnostic home for many children who would be excluded from a bipolar diagnosis but who did display some of its symptoms. With more accurate diagnosis, doctors hope, children in the two bipolar categories, as well as the new one, will receive more appropriate and therefore better treatment.
Despite the proliferation of categories, some children (those with symptoms like Eric's, for example) can be rightly diagnosed with bipolar disorder using stringent criteria. And no matter how they are labeled, children who display pathological mood swings experience significant distress and are in dire need of proper care.