Complex Patterns of Altered White Matter Structural Connectivity within a 'subjective valuation network' in...

Area of Science:

• Neuroscience
• Radiology
• Psychiatry

Background:

• Treatment-resistant depression (TRD) presents a significant clinical challenge.
• Understanding TRD's neurobiological basis is crucial for improved therapeutics.
• The subjective valuation network (SVN) is implicated in motivated behavior and emotional regulation, often altered in depression.

Purpose of the Study:

• To investigate white matter microstructure and structural connectivity in the SVN of individuals with TRD.
• To identify potential neuroimaging biomarkers for treatment resistance in depression.
• To explore correlations between white matter integrity, depression severity, and anhedonia.

Main Methods:

• Diffusion Tensor Imaging (DTI) was used to analyze white matter integrity in 44 TRD patients and 42 controls.
• Tract-Based Spatial Statistics (TBSS) and probabilistic tractography assessed fractional anisotropy (FA) and SVN structural connectivity.
• Key SVN regions included vmPFC, ACC, ventral striatum, and insula.

Main Results:

• Individuals with TRD showed reduced FA in the left uncinate fasciculus, left inferior fronto-occipital fasciculus, and anterior cingulum.
• SVN subcircuits connecting the insula-vmPFC, striatum-insula, and striatum-vmPFC exhibited altered structural connectivity.
• Hyperconnectivity was observed in insula-vmPFC and striatum-vmPFC tracts, while striatum-insula tracts showed hypoconnectivity in TRD patients.

Conclusions:

• TRD is associated with widespread white matter microstructure disruption and altered SVN subcircuit connectivity.
• These structural alterations, including hyper- and hypo-connectivity, may underlie core TRD symptoms like anhedonia.
• Altered SVN structural connectivity could be a key factor in TRD pathophysiology, potentially serving as a biomarker for personalized treatments.