June 2, 2006

Fear Circuit Flares as Bipolar Youth Misread Faces

photo of a brain scan The left amygdala and related structures (yellow area where lines intersect) are part of an emotion-regulating brain circuit where children with bipolar disorder showed greater activity when rating their fear of neutral faces.NIH, National Institute of Mental Health

Compared to healthy children, those with bipolar disorder (BD) see greater hostility in neutral faces and feel more fear when viewing them. They also have more activity in emotion-regulating areas of the brain when they focus on emotional aspects of neutral faces, researchers at NIH’s National Institute of Mental Health have discovered. The new 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% of children.

Studies using Magnetic Resonance Imaging (MRI) to see inside the brain have shown that the amygdala, a fear hub in the brain, is smaller in children with BD than in healthy age-mates. The data in adults isn't as clear. The NIMH research team reasoned that studying the disorder in children may yield insights into how BD develops. Using functional MRI, they measured brain activity in 22 bipolar and 21 healthy youth while they rated neutral faces.

In the May 29, 2006, Proceedings of the National Academy of Sciences, the researchers report that the left amygdala and its related structures were activated more in youth with BD than in healthy youth when they were asked to rate the emotional aspects of faces (hostility, subjects’ fearfulness), but not when they rated a non-emotional feature such as nose width. Those with BD rated themselves as more afraid, and rated the neutral faces as more hostile, compared to healthy peers. The more they misinterpreted the faces as hostile, the more their amygdalas flared. Such a face-processing deficit could help account for the poor social skills, aggression and irritability that characterize this disorder in children

“Our results suggest that children with bipolar disorder see emotion where other people don’t,” explained senior author Dr. Ellen Leibenluft.

The results suggest that BD likely stems from impaired development of specific brain circuits. The researchers will follow up with studies of children at genetic risk for developing BD to see if they have the same amygdala over-activation.

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