Understanding Extreme Irritability in Children

Results of a new study may help improve the diagnosis and treatment of two debilitating childhood mental disorders — pediatric bipolar disorder and a syndrome called severe mood dysregulation (SMD).

Defining pediatric bipolar disorder is a major issue in child psychiatry because the disorder tends to be severe in this age group and the number of diagnosed cases is rising. 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.

Some researchers maintain that pediatric bipolar disorder should be defined to include children with SMD, which was only recently recognized as a distinct disorder. Children with SMD are extremely irritable and hyperactive but do not have clear-cut manic episodes. There are no systematic studies on its treatment, and children with SMD are often treated as if they have bipolar disorder.

To compare the two disorders, Dr. Ellen Leibenluft and her colleagues at NIH's National Institute of Mental Health (NIMH), in collaboration with researchers at the University of Maryland, enrolled 21 children between 7 and 17 years old with SMD, 35 with bipolar disorder and 26 with neither for comparison. The researchers measured electrical signals in different areas of the children's brains during tasks designed to be mildly frustrating.

In the February 2007 issue of the American Journal of Psychiatry, the team reported that children in both the SMD and bipolar disorder groups became more frustrated than comparison children. The children with the two disorders, however, had very different brain activity patterns. Different brain mechanisms may therefore lead to the irritability in these two disorders, suggesting they may require different treatments.

"These aren't children with the occasional bad moods you see in most kids," NIMH Director Dr. Thomas Insel commented. “They're typically very ill, with symptoms that interfere with their lives in major ways. Establishing clear diagnostic criteria is an essential step toward making sure they get the help they need.”

Clinicians currently diagnose mental illnesses like these based on symptoms alone. This research supports the idea that clinicians may one day be able to use biological measurements to help make psychiatric diagnoses.

— by Susan Cahill