Comparison of manic and depressive symptoms between children and adolescents with bipolar spectrum disorders.

Objective: To compare the most severe lifetime (current or past) mood symptoms, duration of illness, and rates of lifetime comorbid disorders among youth with bipolar spectrum disorders [BP (bipolar-I, bipolar-II and bipolar-not otherwise specified)].
Methods: A total of 173 children (<12 years) with BP, 101 adolescents with childhood-onset BP, and 90 adolescents with adolescent-onset BP were evaluated with standardized instruments.
Results: Depression was the most common initial and frequent episode for both adolescent groups, followed by mania/hypomania. Adolescents with childhood-onset BP had the longest illness, followed by children and then adolescents with adolescent-onset BP. Adjusting for sex, socioeconomic status, and duration of illness, while manic, both adolescent groups showed more 'typical' and severe manic symptoms. Mood lability was more frequent in childhood-onset and adolescents with early-onset BP. While depressed, both adolescent groups showed more severe depressive symptoms, higher rates of melancholic and atypical symptoms, and suicide attempts than children. Depressed children had more severe irritability than depressed adolescents. Early BP onset was associated with attention-deficit hyperactivity disorder, whereas later BP onset was associated with panic, conduct, and substance use disorders. Above-noted results were similar when each BP subtype was analyzed separately.
Conclusions: Older age was associated with more severe and typical mood symptomatology. However, there were differences and similarities in type, intensity, and frequency of BP symptoms and comorbid disorders related to age of onset and duration of BP and level of psychosocial development. These factors and the normal difficulties youth have expressing and modulating their emotions may explain existing complexities in diagnosing and treating BP in youth, particular in young children, and suggest the need for developmentally sensitive treatments.