In fMRI studies that will be published soon, both 26 children with bipolar disorder and 22 children with severe mood dysregulation showed deficits in "response reversal" tasks (which would make a person more prone to experience frustration), compared with 34 control children, she said.
In this task, subjects are asked to select between two objects, told that one will win them points and the other will lose them points, and occasionally, the objects will switch roles without announcement. It’s an assessment of one’s ability to adapt to changes in the environment.
"In real life, it would sort of be as if a child is on the playground and then recess is over. The children have to change what they’re doing and adapt to the environment," Dr. Leibenluft said. "You could see how if you [weren’t able to adapt], you would end up extremely frustrated."
The fMRI studies demonstrated that when the control subjects made an error, the right caudate activated, sending them an error signal to rethink what they’re doing; the caudate did not alert the children with bipolar disorder or severe mood dysregulation.
The right inferior frontal gyrus, which plays an important role in attention when adaptation is required, activated in both the control children and those with bipolar disorder when they made an error in the task, but the children with severe mood dysregulation showed much less activation in this area, she said.
Studies will continue to tease out the similarities and differences between bipolar disorder and severe mood dysregulation as distinct categories or part of a spectrum. "This is where, ultimately, far down the line, imaging may be able to complement clinical assessment in differential diagnosis," she said.
Dr. Leibenluft’s research is funded by the National Institutes of Mental Health. The European College of Neuropsychopharmacology paid her expenses to speak at the meeting.