Further evidence of unique developmental phenotypic correlates of pediatric bipolar disorder: Findings from a large sample of clinically referred preadolescent children assessed over the last 7 years

A comparison of the prevalence, clinical correlates, and patterns of comorbidity among children with bipolar disorder (BPD) assessed in the early 1990s (1st cohort) with those evaluated over the last 7 years (2nd cohort). Subjects in both cohorts were children aged ≤12 years referred to a child psychiatry service and evaluated with identical assessment methods. Children with a DSM-III-R BPD diagnosis (1st cohort, n=43; 2nd cohort, n=129) were identified. For comparison purposes, we used attention-deficit/hyperactivity disorder (ADHD) children without BPD referred to the same clinic during the same time period (1st cohort, n=164; 2nd cohort, n=450). Analogous to 1st cohort findings, 2nd cohort results showed that (1) mania was identified in 17% of subjects; (2) the clinical picture was predominantly irritable and mixed, and the course was chronic; (3) BPD children frequently met criteria for major depression, ADHD, psychosis, and anxiety disorders; and (4) BPD children had high rates of psychiatric hospitalization and had evidence of severely impaired psychosocial functioning. These findings confirm that pediatric BPD is a severe clinical disorder afflicting a sizable number of referred preadolescent children. Its unique phenotypic features and patterns of comorbidity support the hypothesis that clinically referred pediatric bipolar disorder represents a very severe developmental subtype of bipolar disorder.