Disrupted interhemispheric functional and structural connectivity in patients with major depressive disorder

Area of Science:

• Neuroscience
• Neuroimaging
• Psychiatry

Background:

• Major Depressive Disorder (MDD) is characterized by disrupted interhemispheric cooperation.
• The precise relationship between structural and functional brain changes in interhemispheric communication in MDD patients is not fully understood.

Purpose of the Study:

• To investigate the associations between voxel-mirrored homotopic connectivity (VMHC) and radial diffusivity (RD) in the corpus callosum (CC).
• To examine the links between these connectivity measures and depressive symptoms in MDD patients.

Main Methods:

• Utilized resting-state functional MRI (rs-fMRI) and diffusion MRI (dMRI) on 60 MDD patients and 38 healthy controls (HCs).
• Assessed interhemispheric functional connectivity (VMHC) and structural integrity (RD) in CC subregions.
• Performed group comparisons, correlation analyses, and mediation analyses.

Main Results:

• MDD patients exhibited reduced VMHC in the bilateral postcentral and lingual gyri and increased RD in CC subregions (CC3, CC4, CC5).
• Lower lingual gyrus VMHC correlated negatively with depressive severity; increased RD in CC4 and CC5 correlated positively with depressive symptoms.
• Mediation analysis showed lingual gyrus VMHC fully mediated the relationship between CC5 RD and depressive symptoms.

Conclusions:

• Findings suggest disrupted interhemispheric coordination in MDD, with both functional and structural impairments linked to symptom severity.
• The mediating role of lingual gyrus VMHC highlights its potential significance in MDD pathophysiology.
• Results offer an integrated view of brain functional and microstructural organization in MDD.