• Science Update
The parents of children who have bipolar disorder are more likely to have bipolar disorder themselves than the parents of children who have severe mood dysregulation (SMD). This finding challenges the notion of some research that suggests SMD is a type of more broadly defined childhood bipolar disorder. The study by NIMH researchers was published in the August 2007 issue of the American Journal of Psychiatry.
The classic definition of bipolar disorder includes episodes of extreme, sustained mood swings. Children with bipolar disorder have manic episodes of elated mood and/or irritability and increased activity, in addition to episodes of depression. In contrast, children with SMD are chronically irritable and hyperactive, without clear-cut manic episodes. However, because both children with SMD and those with bipolar disorder can be irritable and hyperactive, children with SMD may be thought to possibly have another form of bipolar disorder, which can affect treatment decisions.
Because bipolar disorder is known to run in families, one way to test whether SMD is a type of bipolar disorder is to study the family's mental health. In their study, Melissa Brotman, Ph.D., Ellen Leibenluft, M.D., and colleagues in the NIMH Mood and Anxiety Disorders Program suggested that if SMD is a broadly defined type of bipolar disorder, then parents of children with SMD should have bipolar disorder as often as parents of children with strictly-defined bipolar disorder. They found that about 33 percent of parents of children with bipolar disorder had bipolar disorder themselves. In comparison, only about 2.7 percent of parents of children with SMD had bipolar disorder. Bipolar disorder was the only mental illness diagnosed at significantly different rates between the two parent groups.
According to the researchers, these findings suggest that children with symptoms of SMD may not have a type of bipolar disorder.
Brotman MA, Kassem L, Reising MM, Guyer AE, Dickstein DP, Rich BA, Towbin KE, Pine DS, McMahon FJ, Leibenluft E. Parental Diagnoses in Youth With Narrow Phenotype Bipolar Disorder or Severe Mood Dysregulation . Am J Psychiatry. 2007 Aug;164(8):1238-1241.