Disrupted structural connectivity network in treatment-naive depression.

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Neuroimaging indicates abnormal functional connectivity in treatment-naive depression (TD).
• The underlying structural basis for these functional changes in TD remains unclear.

Purpose of the Study:

• To investigate the structural connectivity and topological organization of brain networks in early adult-onset, first-episode TD patients.
• To identify specific structural network alterations associated with TD using diffusion tensor imaging and graph theory.

Main Methods:

• Diffusion tensor imaging tractography was used to build structural connectivity networks in 22 TD patients and 19 healthy controls (HC).
• Graph theory and network-based statistic (NBS) analyses were applied to assess whole-brain structural topology and connectivity differences.

Main Results:

• TD patients exhibited altered structural topological measures, including decreased shortest path length, normalized clustering coefficient, and small-worldness, with increased global and local efficiency.
• NBS identified two distinct altered structural sub-networks in TD patients.
• These sub-networks involved disrupted connections primarily between the orbitofrontal cortex (OFC) and regions such as the insula, putamen, and caudate in both hemispheres.

Conclusions:

• Treatment-naive depression is associated with significant disruptions in the topological organization of structural brain networks.
• Altered orbitofrontal connectivity is a key finding that may contribute to the characteristic symptoms of TD.
• These structural abnormalities provide a potential basis for understanding functional disturbances in mood and cognition in depression.