Investigator Mani N. Pavuluri, M.D., Ph.D., and colleagues at the University of Chicago used functional magnetic resonance imaging (fMRI) to probe the brain-circuit dysfunctions underlying disturbances in emotion processing and emotional reactivity in children with bipolar disorder. The results of the study were reported in the March 2009 issue of the Journal of the American Academy of Child & Adolescent Psychiatry.
As Dr. Pavuluri explained, “problems of emotional processing are core aspects of pediatric bipolar disorder.” For the study, she and her team recruited 20 children, 10 healthy controls and 10 unmedicated children with bipolar disorder with a mean age of 14 years. The subjects were presented with a task that consisted of a "directed" emotion processing condition in which they judged whether the emotion in facial expressions was positive or negative, and also an "incidental" task where they judged whether faces expressing similar affect were older or younger than 35 years. In other words, they were assessed in terms of emotionally charged vs. uncharged thinking.
The research, which was supported by a NARSAD Young Investigator grant, showed that relative to the directed condition, the incidental condition elicited greater activation in the right amygdala and the right insula, the left middle frontal gyrus, and the left posterior cingulate cortex in the children with bipolar disorder in contrast to the controls, who showed greater activation in the right superior frontal gyrus. In both incidental and directed conditions, the bipolar children showed less activation in the right prefrontal cortex and greater activation in the posterior visual and face-processing regions.
The amydala is a key regulator of emotion. The study concluded that the increased amygdala activation observed in the subjects with pediatric bipolar disorder elicited by incidental emotional processing relative to directed emotional processing may indicate more intense automatic emotional reactivity. Furthermore, the right prefrontal systems that are believed to modulate affect seem to be less engaged in these children regardless of whether the emotion processing is incidental or directed, which may signify reduced top-down control of emotional reactivity.
(This article was adapted with permission from the Journal of the American Academy of Child & Adolescent Psychiatry.)