Unique, age specific aspects of the pediatric bipolar disorder (BP) phenotype continue to be debated. According to the DSM-IV1
criteria, irritability and elation are core features of the pathological alteration in affect and mood in the manic phase of bipolar disorder, but there is no consensus on the differential significance of these symptoms in children and adolescents. 2-12
In this regard, a recent series of reports13,14
, documenting a dramatic rise in the reported cases of bipolar illness among children and teens, underscores growing concern with diagnostic error in this age group and, accordingly, the need for rigorous, empirical research to illuminate unique psychopathological features of these core elements. While some assert that severe, explosive irritability is more common in bipolar children than euphoria or elation 2-5,12
Geller and colleagues,9,15
taking note of potential overlap in diagnostic symptoms between early childhood bipolar illness and multiple other forms of severe childhood psychopathology, have argued for the diagnostic centrality of elation and/or grandiosity in research of pediatric bipolar disorder in order to minimize risk of diagnostic imprecision. Notably, in a review and meta-analysis of seven studies, with differing methodologies, of juvenile bipolar subjects completed between 1982 and 2004, Kowatch and colleagues 16
report that rates of irritability and elation vary widely across study samples.
In an attempt to define diagnostic boundaries more sharply, Leibenluft and colleagues 17
have operationalized three clinical phenotypes of bipolar disorder: narrow, intermediate, and broad. Narrow phenotype bipolar disorder is defined as a child having at least one episode in which full DSM-IV criteria are met, including duration criteria and the presence of elation and/or grandiosity. The intermediate phenotype has two subtypes: 1) mania or hypomania NOS (episodes too short to meet DSM-IV duration criteria) and 2) irritable mania or hypomania. Broad phenotype children are characterized by chronic irritability and hyperarousal but specifically exclude patients with elation, grandiosity, and decreased need for sleep. Importantly, this same research group has also subtyped irritability according to course (chronic vs. episodic) and found that episodic irritability was associated with bipolar disorder and anxiety while chronic irritability, or broad phenotype, was more closely associated with ODD, CD, and ADHD and possible increased risk to develop MDD. 18
Other recent reports further underscore the potential importance of distinguishing irritability and elation within the pediatric bipolar spectrum. Rich and colleagues compared subjects with disruptive behavior disorders (DBDs) and severe mood dysregulation to narrow phenotype bipolar subjects and found differences in psychophysiological measures, thus indicating that the biological substrate of irritability may vary between diagnostic groups.19
Brotman and colleagues have compared parents of youth with DBDs and severe mood dysregulation to parents of youth with narrow phenotype bipolar disorder, finding that bipolar disorder was significantly more likely in parents of narrow phenotype bipolar disorder.20
Masi and colleagues reported on 136 BP-I patients (40% female) with mean age of 13.5 who were clinically sub-typed into chronic vs. episodic course and “prevalent elated” vs “prevalent irritable” and found that elated mood was more frequent in patients with an episodic course while irritable mood was more frequent in patients with a chronic course.21
Reflecting these disparate observations and commentary, the National Institute of Mental Health Research Roundtable on Pre-pubertal Bipolar Disorder22
has advocated further clinical observational research to extend our knowledge of the correlates and predictive value of these symptoms. Thus, at this time the differential significance of irritability versus elated mood with regard to factors such as disease course, psychosocial adjustment, non-affective diagnostic comorbidity, and treatment response remains conjecture.
The main goals of this study were to determine whether mania/hypomania in youth may be manifested with only irritability without elation and whether children with bipolar disorder who have irritability and no elation differ on socio-demographic, phenomenological, and familial features from those who have elation and no irritability and from those who have both. The most severe lifetime symptoms (at intake or in the past) were chosen because of the increased likelihood that these symptoms would be better remembered by parents and youth. The main hypotheses tested in this study are that, as indicated in the DSM-IV, BP may be manifested with irritability without elation and that groups formed based upon the presence or absence of irritability or elation will not differ when compared socio-demographically, phenomenologically, and with regard to family history during the most severe lifetime manic episode. An absence of a difference between the groups would add support for the equal importance of these symptoms in the diagnosis of BP and support the inclusion of subjects with irritable mania in future research studies of pediatric BP.
The participants were subjects enrolled in the Pittsburgh, Brown, UCLA multisite study, “Course and Outcome of Bipolar Illness in Youth” (COBY), which is investigating the long-term psychopathological course, outcome, and effectiveness of naturalistic treatment exposure in pediatric BP. The sample is ideally suited for this investigation because of the large sample, the rigorous application of diagnostic criteria, the availability of family history data, and the enrollment of all subjects in long term prospective follow-up assessments. Additionally, the large size of the COBY sample allows for the formation of mood consistent subgroups categorized by the most severe lifetime manic episode which allows for the investigation of the above hypotheses. Since COBY is following all subjects, future studies will be able to evaluate the above-noted hypotheses prospectively and the stability the manic symptoms overtime.