Concurrent inflammation-related brain reorganization in multiple sclerosis and depression

Area of Science:

• Neuroimaging
• Neuroinflammation
• Psychiatry
• Neurology

Background:

• Neuroinflammation is implicated in multiple sclerosis (MS) and major depressive disorder (MDD).
• The role of advanced magnetic resonance imaging (MRI) in detecting neuroinflammatory activity at the gray-to-white matter border in MDD and MS is unclear.

Purpose of the Study:

• To investigate whether gray-to-white matter contrast (GWc) MRI characteristics can serve as a proxy for neuroinflammatory activity in MDD and MS.
• To analyze structural network alterations in patients with MDD and MS using GWc-derived connectivity.

Main Methods:

• Included 684 participants: MDD patients (recurrent and single episodes), MS patients (with and without depressive symptoms), and healthy controls.
• Utilized 3T-T1w MRI to derive GWc and characterize GWc-covariance networks (modularity, clustering coefficient, degree).
• Employed a support vector machine to assess GWc's ability to stratify groups based on depression severity (BDI).

Main Results:

• Both MDD and MS patients exhibited increased network modularity and clustering compared to healthy controls.
• A gradient of increasing modularity was observed from healthy controls to MS patients (with/without depression) and MDD patients (single/recurrent episodes).
• Reduced GWc correlated with increased depressive symptoms and was significantly associated with depression scores across patient groups. Depressive symptoms in MS were classified with 88% accuracy.

Conclusions:

• Structural network alterations detected by GWc analyses are similar in MDD and MS, suggesting common underlying inflammatory events like demyelination and neuroinflammation.
• These alterations appear to vary with symptom severity.
• GWc analysis may help elucidate the occurrence of comorbid depression in MS.