Peripheral inflammation is associated with micro-structural and functional connectivity changes in depression-related...

Area of Science:

• Neuroscience
• Immunology
• Psychiatry

Background:

• Major depression is linked to inflammation and altered brain function.
• The precise relationship between systemic inflammation, brain microstructure, and functional connectivity in depression is not fully understood.

Purpose of the Study:

• To investigate the association between C-reactive protein (CRP) levels, brain micro-structural parameters, and functional connectivity in healthy controls and individuals with major depression.
• To explore how peripheral inflammation might affect the default mode network (DMN) in depression.

Main Methods:

• Recruited 46 healthy controls and 83 depressed cases, stratified by CRP levels.
• Collected clinical data, blood samples for CRP assay, and performed brain magnetic resonance imaging (MRI).
• Measured micro-structural MRI parameters (e.g., proton density) and resting-state functional connectivity (weighted degree) across cortical and subcortical regions, controlling for false discovery rate.

Main Results:

• Elevated CRP levels correlated with increased proton density (a marker of edema) in the precuneus, posterior cingulate cortex (pC/pCC), and medial prefrontal cortex (mPFC).
• CRP was also associated with altered functional connectivity between pC/pCC, mPFC, and the hippocampus.
• Depression was linked to reduced functional connectivity (hubness) in DMN nodes, including pC/pCC and mPFC.

Conclusions:

• Peripheral inflammation, indicated by CRP, affects brain micro-structure and functional connectivity within DMN nodes.
• These inflammation-associated changes in DMN microstructure and connectivity may be a mechanism through which inflammation contributes to depressive symptoms.
• Findings suggest a neurobiological link between systemic inflammation and the pathophysiology of major depression.