Experts in the U.S., in an attempt to define the abnormalities in the brains of people with bipolar disorder, have used used functional MRI to measure levels of metabolic activity in different areas of the brain.
The investigators say their work could lead to new drug treatments and better coping strategies for sufferers of the condition.
People with bipolar disorder suffer from extreme swings in mood, from depression to mania.
Dr. Stephen M. Strakowski and colleagues from the University of Cincinnati - Department of Psychiatry used functional MRI, to examine the brains of 10 patients with bipolar disorder while they were in a manic episode along with 15 healthy people.
Strakowski explained that the study participants performed a "stop-signal task," in which they were instructed to respond to projected letters depending on the letter color, which provided a measure of impulse control.
According to Strakowski, during the test, bipolar patients exhibited increased activation in a network of brain regions known to involve the control of emotion and emotional expression, and found that these mood networks are connected with the cognitive networks, so when mood networks are over activated they interfere with cognition, which leads to reduced impulse control.
The researchers looked at areas of the posterior brain which are usually involved in attentional processes in healthy people. These areas become activated as attentional tasks become more difficult.
The researchers say that it appears that in bipolar patients these areas are activated at baseline, which suggests that they try to recruit these compensatory areas to manage the interference from the emotional network.
Strakowski says this means that bipolar patients tend not to trade speed for accuracy as tasks become more complicated, and they won't slow down to do better.
He is hopeful that the findings will lead to new therapeutic approaches for bipolar disorder, such as helping patients learn how to delay reactions so that decision-making is more functional.
The researchers will be assisted by these results in the next stage of their work, which is to use other imaging methods like magnetic resonance spectroscopy to define neurochemical abnormalities that underlie these abnormal activations.
Drug development might in future directly target these neurochemical abnormalities.
The study was presented at the International Conference on Bipolar Disorder in Pittsburgh.