Older bipolar disorder patients have inferior frontal lobe gray matter volume deficits, including in areas associated with the anterior limbic network, US researchers have discovered.

Although structural magnetic resonance imaging (MRI) studies have revealed inconsistent results in the assessment of volumetric changes in bipolar disorder patients, several investigations have indicated that regional abnormalities are present in such patients, predominantly in the frontal and temporal lobes.

John Beyer and colleagues from Duke University Medical Center in Durham, North Carolina administered structured clinical interviews and performed MRI scanning on 56 bipolar disorder patients with an average age of 60.5 years and 43 healthy individuals with an average age of 58.1 years. The cerebrum was divided into 16 units using image parcellation.

There were no significant differences between patients and controls in terms of age, gender, or race, the team notes in the International Journal of Geriatric Psychiatry. There were also no differences in total gray matter volume between patients and controls.

However, analysis revealed a significant bilateral difference in gray matter volume in patients versus controls in the anterior half of the brain, particularly in the anterior??”inferior brain regions. This difference remained significant even after controlling for age and gender.

Again, no overall total white matter volume differences were observed between patients and controls. Some differences were found in anterior brain regions, but these did not remain after taking into account age and gender.

“Our observation of decreased gray matter volume in the inferior frontal areas of the brain suggests that these areas may play a primary role in the mood and cognitive symptoms of bipolar disorder, and complements previous structural neuroimaging studies that suggest an underlying neuropathology in the anterior limbic network,” the researchers conclude.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

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