|Fear Circuit Flares as Bipolar Youth Misread Faces
Youth with bipolar disorder misread facial expressions as hostile and show
heightened neural reactions when they focus on emotional aspects of neutral faces,
researchers at the National Institutes of Health’s (NIH) National Institute of
Mental Health (NIMH) have discovered. The 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 one percent of children.
Brain scans showed that the left amygdala, a fear hub, and related structures,
activated more in youth with the disorder than in healthy youth when asked to
rate the hostility of an emotionally neutral face, as opposed to a non-emotional
feature, such as nose width. 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 characterizes the
disorder in children, suggest Drs. Ellen Leibenluft, Brendan Rich, Daniel Pine,
NIMH Mood and Anxiety Disorders Program, and colleagues, who report on their
findings May 29, 2006 in the Proceedings of the National Academy of Sciences.
“Since children seem to have a more severe form of the disorder, they may provide
a clearer window into the underlying illness process than adult onset cases,” explained
Leibenluft. “Our results suggest that children with bipolar disorder see emotion
where other people don’t. Our results also suggest that bipolar disorder likely
stems from impaired development of specific brain circuits, as is thought to
occur in schizophrenia and other mental illnesses.”
Magnetic Resonance Imaging (MRI) studies have shown that, unlike in adults with
the illness, the amygdala is consistently smaller in bipolar children than in
healthy age-mates. Also, the NIMH researchers had found earlier that bipolar
children falter at identifying facial emotion and have difficulty regulating
their attention when frustrated.
Using functional MRI, the researchers measured brain activity in 22 bipolar
youth and 21 healthy subjects while they rated faces. In addition to the amygdala,
other parts of the emotion-regulating circuit — nucleus accumbens, putamen,
and left prefrontal cortex — were also hyperactive in patients, compared
to healthy peers, during the emotional tasks. Patients rated themselves as more
afraid, and they rated the faces as more hostile, compared to healthy peers.
The groups did not differ on nose width ratings, confirming that the differences
were specific to perceiving emotional processes.
“By finding a brain imaging trait that may be more selective than current clinical
criteria, this line of research might help us refine our definition of pediatric
bipolar disorder,” said NIMH Director Thomas Insel, M.D. “The researchers are
following-up with imaging studies of children with bipolar spectrum disorders
and healthy children who are at genetic risk for developing the disorder to see
if they also have the same amygdala over-activation.”
Also participating in the study were: Dr. Deborah Vinton, Dr. Rebecca Hommer,
Dr. Stephen Fromm, Lisa Berghorst, NIMH; Dr. Roxann Roberson-Nay, Virginia Commonwealth
University; Dr. Erin McClure, Georgia State University.
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 activation than controls
when rating their fear of neutral faces. Structural MRI image with functional
MRI data superimposed.
Source: NIMH Mood and Anxiety Disorders Program
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