Early childhood temperament in pediatric bipolar disorder and attention deficit hyperactivity disorder.

Recent theories suggest that children with pediatric bipolar disorder (PBD) may exhibit more difficult temperaments premorbidly, including traits such as behavioral disinhibition and difficulty with emotion regulation. We investigated temperament characteristics retrospectively during infancy and toddlerhood in subjects with PBD (n=25), attention-deficit/hyperactivity disorder (ADHD; n=25), and healthy controls (n=25). Children with PBD were reported to experience increased difficult temperament in both infancy and toddlerhood compared to children with ADHD. Several characteristics of difficult temperament were associated with residual symptoms of mania and depression. Difficult premorbid temperament characteristics may be a specific indicator of a bipolar diathesis, or might signal underlying dysfunction in affective processes that significantly increase risk for a mood disorder.