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18-01-2012 | Mental health | Article

Limbic network disruption may characterize bipolar disorder

Abstract

Free abstract

MedWire News: Results from a Chinese study show that bipolar disorder (BD) patients have gray and white matter abnormalities that indicate disorganization of the limbic network.

"Structural abnormality of both gray and white matter has been detected in patients with BD," write Tao Li (Sichuan University, Chengdu) and colleagues in Progress in Neuro-Psychopharmacology and Biological Psychiatry.

But they add that "results have been greatly inconsistent across studies of BD to date, most likely due to the inclusion of clinically heterogeneous samples."

To address this, the researchers enrolled 18 male inpatients with BD who were experiencing a first episode of psychotic mania and 27 age- and education-matched mentally healthy men (controls).

The BD patients were being treated with standard pharmacotherapy that included mood stabilizers and/or antipsychotic drugs, but treatment had started no more than 5 days before enrolment in the current study.

All of the participants underwent magnetic resonance imaging and diffusion tensor imaging (DTI) of the brain, with between-group differences in gray and white matter assessed using voxel-based morphometry (VBM) and voxel-based analysis of fractional anisotropy (FA) maps, respectively.

Results from the VBM analysis revealed no significant differences between BD patients and controls regarding whole brain gray and white matter volumes, or total intracranial volumes.

However, BD patients showed significantly increased gray matter volumes in the left thalamus and bilateral basal ganglia, including the bilateral putamen and extending to the left claustrum, compared with controls.

Results from the voxel-based analysis of DTI scans revealed that BD patients had significantly reduced FA values in left parietal white matter, corresponding to fibers of the left posterior corona radiata, compared with controls.

Li and team conclude: "Our study revealed increased gray matter volume in the thalamus, putamen and the claustrum, as well as reduced FA values of white matter in the posterior corona radiata among male patients, indicating the involvement of the limbic network in BD."

They add: "Further studies are essential to clarify this issue in female patients and to elucidate the pathophysiology and significance of brain structural abnormalities in BD."

By Mark Cowen

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