Misreading faces and seeing hostility where there is none could be a significant factor contributing to the poor social skills, aggression, and irritability that characterize bipolar disorder in children.

Researchers at the National Institutes of Health's National Institute of Mental Health say their study provides some of the first clues to the underlying workings of the episodes of mania and depression that disrupt friendships, school and family life in up to 1 percent of children.

Brain scans showed that the left amygdala, a fear hub, and related structures were activated more in youths with the disorder than in healthy youths, when they were asked to rate the hostility of an emotionally neutral face as opposed to a non-emotional feature, such as nose width.

Sheds Light on the Disorder

The more patients misinterpreted the faces as hostile, the more their amygdala flared.

Such a face-processing deficit could help account for the poor social skills, aggression, and irritability that characterize the disorder in children, suggest Drs. Ellen Leibenluft, Brendan Rich, Daniel Pine and colleagues

The study appears in the Proceedings of the National Academy of Sciences.