Researchers at the University of Illinois at Chicago used functional brain imaging to establish a link between emotional impairment and poor cognition in children with bipolar disorder.
"This study is very exciting because it shows that negative emotions affect cognition differently than positive emotions in these kids," said Dr. Mani Pavuluri, associate professor of psychiatry at UIC's Institute for Juvenile Research and the Center for Cognitive Medicine, and lead author of the study.
Using functional magnetic resonance imaging, Pavuluri and her colleagues examined the brain activity of teens while they were performing certain mental tasks. The researchers scanned the brains of 10 unmedicated bipolar patients with normal mood and compared them with 10 healthy subjects of the same age and gender.
The children, aged 12 to 18, were asked to match positive or negative words with colors to determine how stimuli impact different areas of the brain responsible for emotion and cognition.
When shown negative words, compared to neutral words, the bipolar patients showed increased activation in the part of the brain that regulates emotions. When shown positive words, they showed activation in the reward centers of the brain which are often associated with pleasure and addiction.
In healthy subjects, positive and negative words activated the regions of the brain associated with cognitive behavior such as thinking, reasoning and learning.
"We found that the amygdala, the part of the brain that is supposed to react to emotional stimuli, is over-reactive to negative stimuli in children with bipolar disorder," said Pavuluri. "And the part of the brain that controls cognitive behavior is under-reactive."