Elevated Systemic Inflammation Is Associated with Reduced Corticolimbic White Matter Integrity in Depression.

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Inflammation is increasingly recognized as a factor in neural circuit dysfunction and major depressive disorder (MDD) pathogenesis.
• The specific impact of inflammation on white matter pathway integrity in MDD is an emerging area of research.

Purpose of the Study:

• To investigate the relationship between peripheral inflammation and white matter integrity in individuals diagnosed with MDD.
• To determine if markers of inflammation correlate with microstructural alterations in specific white matter tracts.

Main Methods:

• Quantitative anisotropy (QA) derived from diffusion magnetic resonance imaging (dMRI) was used as a measure of white matter integrity.
• QA was regressed against C-reactive protein (CRP) levels in 176 participants with MDD, with adjustments for age, sex, and BMI.
• Robustness of associations was tested by controlling for up to twelve potential confounders.

Main Results:

• A significant negative correlation was found between CRP concentration and QA in multiple white matter tracts, including cortico-striatal tracts, thalamic radiations, and corpus callosum.
• These associations, indicating poorer white matter integrity with higher inflammation, remained significant after controlling for confounders.
• A positive association between CRP and QA in the fornix and parts of the thalamic radiation was observed but did not persist after confounder adjustment.

Conclusions:

• Peripheral inflammation may play a role in the development of major depressive disorder by compromising the microstructural integrity of corticolimbic white matter pathways.
• The findings highlight a potential link between inflammatory processes and white matter abnormalities in MDD.