White matter microstructural abnormalities in euthymic bipolar disorder.

Area of Science:

• Neuroimaging
• Neuropsychiatry
• White Matter Disorders

Background:

• Abnormal diffusion parameters are documented in specific brain areas and white matter tracts in bipolar disorder.
• Previous research suggests localized white matter abnormalities in bipolar disorder.

Purpose of the Study:

• To determine if white matter abnormalities in bipolar disorder are generalized across large brain regions.
• To investigate the extent of white matter microstructural changes in bipolar disorder.

Main Methods:

• Diffusion parameters (mean diffusivity and fractional anisotropy) were measured in multiple white matter regions, including the corpus callosum and deep/periventricular white matter.
• 28 euthymic bipolar disorder patients and controls were studied.
• White matter hyperintensity loads were assessed as a potential confounding factor.

Main Results:

• Bipolar disorder patients showed significantly increased mean diffusivity across all measured sites and reduced fractional anisotropy in most sites compared to controls.
• Diagnosis significantly impacted callosal and deep/periventricular white matter diffusion parameters.
• Specific regions like the prefrontal and periventricular white matter exhibited increased mean diffusivity, while callosal and occipital white matter showed reduced fractional anisotropy.

Conclusions:

• Generalized white matter microstructural abnormalities are likely present in bipolar disorder.
• These abnormalities may be exacerbated by a history of substance use.
• Lithium treatment might have a mitigating effect on these white matter changes.