Resting-State Brain Dynamics Unique to Anxiety in Major Depressive Disorder.

Area of Science:

• Neuroscience
• Psychiatry
• Radiology

Background:

• Major depressive disorder with anxiety (MDD-A) is a proposed subphenotype of major depressive disorder (MDD).
• Differentiating MDD-A from MDD remains debated due to overlapping symptoms and unclear neurobiological distinctions.
• Research on unique brain activity alterations in MDD-A using resting-state functional MRI (R-fMRI) is limited.

Purpose of the Study:

• To investigate dynamic brain activity differences between MDD, MDD-A, and healthy controls using R-fMRI.
• To identify unique neurobiological markers for MDD-A compared to MDD.
• To explore the relationship between anxiety levels and brain activity in MDD and MDD-A.

Main Methods:

• Resting-state functional MRI (R-fMRI) scans were acquired from 30 MDD patients, 45 MDD-A patients, and 46 healthy controls.
• Dynamic analysis generated measures including voxel-mirrored homotopic connectivity and regional homogeneity.
• Kendall's W coefficient assessed concordance between indices, with voxel-wise differences analyzed across groups.

Main Results:

• Both MDD and MDD-A groups showed decreased dynamic R-fMRI indices in several brain regions compared to controls.
• The MDD-A group exhibited reduced voxel-wise concordance in the left medial superior frontal gyrus compared to the MDD group.
• Anxiety levels negatively correlated with voxel-wise concordance in the left medial superior frontal gyrus for both MDD and MDD-A groups.

Conclusions:

• Reduced voxel-wise concordance in the left medial superior frontal gyrus may serve as a neurobiological differentiator for MDD-A versus MDD.
• These findings illuminate the neural underpinnings of anxiety in depression.
• Accounting for heterogeneity in depression research is crucial for understanding underlying mechanisms.