About 3 percent of pre-adolescent and adolescent youth are estimated to have severe mood dysregulation (SMD), a condition similar to pediatric bipolar disorder. Since SMD was only recently defined, there are no systematic studies on its treatment, and children with SMD are often treated as if they have pediatric bipolar disorder. The classic definition of bipolar disorder includes extreme, sustained mood swings that range from over-excited, elated moods and irritability - the manic phase of the disorder - to depression. In contrast, children with SMD are extremely irritable and hyperactive, but do not have clear-cut manic episodes.
Defining pediatric bipolar disorder is a major issue in child psychiatry, because the disorder tends to be severe in this age group and the rate of diagnosed cases is rising. Until recent years, most studies of bipolar disorder were conducted in adults. Some researchers maintain that pediatric bipolar should be defined more broadly to include children with SMD, but a recent study conducted by researchers from the National Institute of Mental Health (NIMH) counters that belief. When the brain's electrical signals were measured during mildly frustrating situations, researchers found a very different pattern in children with SMD, compared with children who had bipolar disorder. The results indicate that different brain mechanisms may lead to irritability in children with SMD, suggesting that they may have an illness other than bipolar disorder and may require different treatments.
