A COMPREHENSIVE EXAMINATION OF WHITE MATTER TRACTS AND CONNECTOMETRY IN MAJOR DEPRESSIVE DISORDER

Area of Science:

• Neuroimaging
• Psychiatry
• Neurology

Background:

• Major Depressive Disorder (MDD) is a complex mental health condition with known brain abnormalities.
• Existing research on white matter abnormalities in MDD shows mixed results.
• This study investigated fractional anisotropy (FA) in white matter tracts of MDD patients using diffusion tensor imaging (DTI).

Purpose of the Study:

• To examine white matter integrity, specifically fractional anisotropy (FA), in individuals diagnosed with Major Depressive Disorder (MDD) compared to healthy controls (HC).
• To explore the relationship between depression severity and age of onset with white matter abnormalities in MDD patients.

Main Methods:

• A multisite study included 139 participants with MDD and 39 HC.
• Diffusion Tensor Imaging (DTI) scans were analyzed using region of interest (ROI), tract-based spatial statistics (TBSS), diffusion tractography, and diffusion connectometry.
• Fractional anisotropy (FA) and white matter pathway connectivity were assessed.

Main Results:

• No significant group differences in FA were found between MDD and HC participants across all analytical methods.
• In the MDD group, FA in the right medial orbitofrontal cortex correlated with depression severity.
• Age of onset of MDD was associated with FA in the right caudal anterior cingulate cortex and connectivity in specific white matter tracts.

Conclusions:

• The heterogeneity of MDD may explain the lack of significant group differences in white matter integrity.
• The correlation between FA and depression severity suggests a potential state biomarker for depression.
• Age of onset appears to be a clinically relevant factor for investigating white matter abnormalities in MDD.