A new study from Bradley Hospital and The Warren Alpert Medical School of Brown University, as well as two other institutions, adds to mounting evidence that clinicians consider irritability as a symptom when diagnosing pediatric bipolar disorder.
Reporting in the July issue of the Journal of the American Academy of Child and Adolescent Psychiatry, researchers say a small percentage of children with bipolar disorder experience manic episodes without extreme elation – one of the hallmarks of the disorder – and are diagnosed based on irritable mood alone.
"Diagnosing children with bipolar disorder is challenging. One of the chief controversies is whether irritability should be included among the criteria for this diagnosis because it can also overlap with a number of other psychiatric disorders, such as attention deficit hyperactivity disorder," says lead author Jeffrey Hunt, MD, a child psychiatrist and training director at Bradley Hospital. "Our findings confirm that while irritable-only mania is uncommon, it does exist – particularly in younger children – and should be considered in a bipolar diagnosis."
Bipolar disorder is characterized by dramatic mood swings from euphoria, elation and irritability – the manic phase of the disorder – to severe depression. Bipolar disorder often begins in late adolescence or early adulthood, although it can develop as early as the preschool years. Recent studies have shown that the number of children and teens being treated for bipolar disorder has grown dramatically in the last decade. Although it is unclear what has caused this increase, experts believe it may be due in part to more aggressive diagnoses by physicians and a greater awareness of pediatric bipolar disorder in the medical community.
Hunt and colleagues studied 361 children between the ages of 7 and 17 with bipolar disorder participating in the multi-site Course and Outcome of Bipolar Illness in Youth (COBY) study at Bradley Hospital and Alpert Medical School, the University of Pittsburgh and the University of California-Los Angeles. COBY is the largest and most comprehensive study of children and adolescents with bipolar disorder to date.
Researchers quantified the frequency and severity of manic symptoms of each participant, including whether irritability and elation were present. Based on this data, the group was then reclassified into three subgroups: elation-only, irritable-only and both elated and irritable.
Approximately 10 percent of children fell into the irritable-only category, while elated-only constituted about 15 percent. Nearly three-quarters experienced both elation and irritability. The irritable-only participants were significantly younger in age than the other two groups; however, there were no other sociodemographic differences between the groups. There were also no significant differences in terms of bipolar subtype, rate of psychiatric comorbidities, severity and duration of illness, and family history of mania and other psychiatric disorders. However, depression and alcohol abuse in second-degree relatives occurred more frequently in the irritable-only subgroup.
"The fact that the irritable-only and elation-only subgroup had similar clinical characteristics and family histories of bipolar disorder provides support for continuing to consider episodic irritability in the diagnosis of pediatric bipolar disorder," says Hunt, who is an assistant professor of psychiatry and human behavior at Alpert Medical School. Hunt is also training director of the child and adolescent fellowship and triple board residency programs.
The authors say continual, long-term follow-up of this study sample will help clarify whether the presence or predominance of elation or irritability at baseline will predict future clinical outcomes.
The research was funded by a grant from the National Institute of Mental Health. Study co-authors include Jennifer Dyl and the late Henrietta Leonard from Bradley Hospital and Alpert Medical School; Christianne Esposito-Smythers, Martin Keller, Lance Swenson and Robert Stout from Alpert Medical School; Boris Birmaher, David Axelson, Neal Ryan, Benjamin Goldstein, Tina Goldstein, MaryKay Gill and Mei Yang from the University of Pittsburgh Medical Center; and Michael Strober from the David Geffen School of Medicine, University of California at Los Angeles.
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