Impaired robust interhemispheric function integration of depressive brain from REST-meta-MDD database in China

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Functional homotopy (FH) describes consistent functional connectivity (FC) between mirrored brain regions.
• Previous studies indicate altered FH in major depressive disorder (MDD) patients, but findings vary regarding affected brain areas.

Purpose of the Study:

• To investigate interhemispheric functional integration in MDD using resting-state functional magnetic resonance imaging (R-fMRI).
• To explore correlations between altered functional homotopy and clinical characteristics in MDD patients.

Main Methods:

• Acquired R-fMRI data from 1004 MDD patients and 898 healthy controls (HCs) across 20 centers in China.
• Utilized voxel-mirrored homotopic connectivity (VMHC) to assess FH patterns and interhemispheric FC.
• Analyzed the relationship between VMHC alterations and clinical factors like age, gender, episode type, and illness severity.

Main Results:

• MDD patients exhibited significantly reduced VMHC across widespread brain regions, notably in the posterior cingulate gyrus/precuneus (PCC/PCu).
• Reductions in the supramarginal gyrus (SMG) and insula were more pronounced with age, with SMG changes being male-specific.
• The middle temporal gyrus (MTG) showed male-specific reductions in MDD.
• VMHC alterations correlated significantly with episode type and illness severity, with higher Hamilton Depression Rating Scale scores linked to greater reduction in the visual cortex.

Conclusions:

• Confirmed widespread VMHC reduction in MDD, especially in the PCC/PCu, highlighting impaired interhemispheric communication.
• Demonstrated that these VMHC alterations are influenced by demographic and clinical factors including gender, age, episode type, and illness severity.
• Suggests that the brain in MDD exhibits a tendency towards decreased information exchange between hemispheres.