Structural Brain Connectivity and Treatment Improvement in Mood Disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Standard treatments for mood disorders are effective for many, but over a third of patients exhibit treatment resistance.
• Understanding the neurobiological underpinnings of treatment-resistant depression is crucial to avoid ineffective therapies and optimize patient outcomes.

Purpose of the Study:

• To investigate the structural brain connectivity differences in patients with mood disorders, distinguishing between treatment-improved and non-improved individuals.
• To identify brain structural correlates associated with treatment resistance in mood disorders.

Main Methods:

• Diffusion magnetic resonance imaging (dMRI) was used for structural connectivity analyses in 154 mood disorder patients and 77 healthy controls.
• Network-based statistics (NBS) and graph theory metrics were employed to analyze regional network architecture and global connectome organization.
• Patients were assessed at baseline and 6-month follow-up, categorized as improved or not-improved (NI) based on clinical evaluations.

Main Results:

• Mood disorder patients showed impaired basal ganglia connections compared to healthy controls.
• Increased local efficiency and clustering were observed in the lingual gyrus, insula, and amygdala in the mood disorder group.
• Improved patients exhibited reduced network integration and segregation in default mode network regions (precuneus, middle temporal lobe, rostral anterior cingulate) compared to non-improved patients.

Conclusions:

• Structural connectivity alterations in the basal ganglia, fronto-limbic network, and default mode network are implicated in mood disorders.
• These findings enhance the understanding of mood disorder pathophysiology and factors contributing to unfavorable treatment outcomes.