Phenomenology of bipolar disorder not otherwise specified in youth: a comparison of clinical characteristics across the spectrum of manic symptoms.

OBJECTIVES Controversy surrounds the diagnostic categorization of children with episodic moods that cause impairment, but do not meet DSM-IV criteria for bipolar I (BD-I) or bipolar II (BD-II) disorder. This study aimed to characterize the degree to which these children, who meet criteria for bipolar disorder not otherwise specified (BD-NOS), are similar to those with full syndromal BD, versus those with no bipolar spectrum diagnosis (no BSD). METHODS Children aged 6-12 years were recruited from nine outpatient clinics, preferentially selected for higher scores on a 10-item screen for manic symptoms. Interviews with the children and their primary caregivers assessed a wide array of clinical variables, as well as family history. RESULTS A total of 707 children [mean ± standard deviation (SD) 9.4 ± 1.9 years old] were evaluated at baseline, and were diagnosed with BD-I (n = 71), BD-II (n = 3), BD-NOS (including cyclothymia; n = 88), or no BSD (n = 545). Compared to BD-I, the BD-NOS group had less severe past functional impairment. However, current symptom severity and functional impairment did not differ between BD-NOS and BD-I, even though both groups were significantly more symptomatic and impaired than the no BSD group. Parental psychiatric history was similar for the BD-NOS and BD-I groups, and both were more likely than the no BSD group to have a parent with a history of mania. Rates of elated mood did not differ between BD-NOS and BD-I youth. CONCLUSIONS Children with BD-NOS and BD-I are quite similar, but different from the no BSD group, on many phenomenological measures. These findings support the hypothesis that BD-NOS is on the same spectrum as BD-I.