Cognitive flexibility in phenotypes of pediatric bipolar disorder

Objective: Clinicians and researchers debate whether children with chronic, nonepisodic irritability should receive the diagnosis of bipolar disorder (BD). To address this debate, we evaluated cognitive flexibility, or the ability to adapt to changing contingencies, in three groups of children: narrow-phenotype BD (NP-BD; full-duration manic episodes of elevated/expansive mood; N = 50; 13.1 +/- 2.9 years), severe mood dysregulation (SMD; chronic, nonepisodic irritability; N = 44; 12.2 +/- 2.1 years), and healthy controls (N = 43; 13.6 +/- 2.4 years). Cognitive flexibility is relevant to symptoms of BD involving dysfunctional reward systems (e.g., excessive goal-directed activity and pleasure-seeking in mania; anhedonia in depression). Method: We studied simple and compound reversal stages of the intra-/extradimensional shift task and change task that involves inhibiting a prepotent response and substituting a novel response. Results: On the simple reversal, NP-BD youths were significantly more impaired than both the SMD group and controls. On the compound reversal, NP-BD and SMD youths performed worse than controls. On the change task, NP-BD youths were slower to adapt than SMD subjects. Conclusions: Phenotypic differences in cognitive flexibility may reflect different brain/behavior mechanisms in these two patient populations.