Over the past 15 years, children and adolescents with severe irritability and aggressive outbursts have received increased attention from medical professionals as more and more of these youths have been diagnosed with pediatric bipolar disorder. In some cases, the pediatric patients clearly meet current diagnostic criteria for bipolar disorder, but in others, the diagnosis is unclear. Without validated biomarkers to diagnose bipolar disorder, the rising trend - with some data suggesting it may have increased as much as 400 percent from 1994 to 2003 - has become one of the greatest controversies in child and adolescent psychiatry. 

A growing number of researchers, however, believe that many of these pediatric patients may have a different disorder, which they have termed Severe Mood Dysregulation (SMD).  A youth with SMD will exhibit outbursts that go far beyond a typical temper tantrum and require clinical intervention, but they will not experience other symptoms such as the manic and prolonged euphoria that often presents with bipolar disorder.