Interest in childhood mood disorders has increased substantially in recent years. This has served as an important antidote to earlier views that assumed, largely on a theoretical basis, that mood disorders were uncommon in children (1). However, the realization that these conditions could be observed in childhood and that they shared important core features with mood disorders in adolescents and adults also came with an awareness of the important effects of development and developmental level on the expression of these conditions. Research and clinical work in childhood mood disorders has been complicated by factors such as the difficulties around differential diagnosis, since the initial presentation may be misleading and diagnostic certainty may be achieved only over time and with the wisdom of hindsight. For example, a child with bipolar disorder can initially exhibit symptoms of overactivity and inattention, and a child with major depression may display irritable mood and anxiety rather than overt depression as the prominent feature. Further problems are posed by the potential for serious mood disorders to impact negatively on the child’s development and, in turn, for the child’s developmental level to modify the presentation of the disorder (1). Three articles in this issue are concerned with mood disorders in children.
Miller and colleagues evaluated the influence of clinical variability and sex differences on regional measures of EEG asymmetry in adults with histories of childhood-onset depression. As they note in their article, this work is based on the findings that asymmetry in frontal brain activity may be a marker for vulnerability to depression and a more general pattern of differences in right and left cortical modulation of emotional expression. In their study, Miller et al. evaluated 55 young adults with histories of well-documented childhood-onset depression and 55 adults with no psychiatric history. EEG patterns were then related to childhood and adult diagnoses; EEG asymmetry differences varied with gender and current symptoms as well as with diagnostic history (e.g, for those individuals with childhood-onset depression who eventually exhibited bipolar disorder). As Miller and her colleagues note, the observed sex differences in EEG asymmetry are particularly important and emphasize the need for future work; such differences are also of interest in light of reported differences in drug responsiveness and the potential for providing more robust biological markers (2).
Geller and co-workers report the results of a 2-year prospective follow-up of children with prepubertal and early adolescent bipolar disorder. As they note, there has been a relative dearth of research on the course of early-onset bipolar disorder. They studied a large group of patients over a 2-year period and, it is important to note, required the presence of mania with elation or grandiosity for study inclusion, thus avoiding the potential for diagnosis to be based only on the criterion for mania (which overlaps with attention deficit hyperactivity disorder [ADHD]). In effect, their use of this criterion means that they selected a group of subjects for whom there would be the most agreement that they did indeed exhibit stringently defined bipolar disorder. As Geller and colleagues note, rates of relapse were quite high. Living in an intact biological family was a predictor of positive outcome, whereas low maternal warmth was a significant predictor of rate of relapse. While various explanations for the relatively poor outcome must be considered, the important possibility that children are less responsive to mood stabilizers cannot be ruled out. The Geller et al. data add significantly to the small but growing body of work on prepubertal-onset bipolar disorder (3).
In their clinical case conference, State and colleagues address the problem of mania and ADHD in a prepubertal child. The boundary between these two conditions has proven a rather difficult one to demarcate (in contrast to adolescence, in which the major differential diagnosis is with schizophrenia ). As State et al. note, the nature of the association between ADHD and bipolar disorder remains controversial, with some arguing that the association is a "true" one (5) and others arguing equally as strong that is it artifactual (6). This debate is an important one, since the tendency to see multiple true disorders would logically lead to polypharmacy, which may or may not be justified. This clinical case conference captures many aspects of this current debate: the child had a history of attentional difficulties and impulsivity and a family history of mood disorder and was first hospitalized for threatening suicide. Although his depressed mood improved following hospitalization, his attentional problems continued. After the introduction of methylphenidate to treat the latter difficulties, he developed more overtly manic symptoms, including pressured speech, diminished sleep, aggression, agitation, and possible grandiosity. The introduction of lithium and haloperidol was associated with some improvement, but eventually the patient was hospitalized on a third occasion following escalating behavioral difficulties. State and colleagues rightly emphasize the adverse impact of the child’s psychiatric problems on his educational achievement and the difficulties of differential diagnosis in a child whose disorder is evolving over time. Their report also underscores the need for additional data to address the problems of comorbidity with ADHD. This problem is particularly important, since children often do not exhibit the more typical euphoria and grandiosity of adults. The problem of comorbidity here is a significant one in that treatment with stimulants or antidepressants may precipitate mood episode switches, although this issue remains controversial.
These three studies underscore the importance of research on childhood mood disorders. The lack of treatment efficacy data on these conditions is most unfortunate. As State and colleagues indicate, there are currently no placebo-controlled trials of mood-stabilizing agents in children with bipolar disorder. Various issues remain to be resolved by future research. These include the problem of comorbidty and the issue of whether more sophisticated diagnostic schemes are needed for this population. The important issue of the treatment of attentional symptoms in children with family histories of mood disorder or features suggestive of mood disorder also remains a major priority.
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