Multimetric structural covariance in first-episode major depressive disorder: a graph theoretical analysis

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) is associated with focal abnormalities in cortical thickness, surface area, and gyrification.
• It remains unclear if these focal changes impact the brain's system-level architecture or topology in MDD.

Purpose of the Study:

• To investigate system-level topological disruptions in brain morphology in patients with first-episode major depressive disorder (MDD).
• To determine if morphological covariance networks differ between MDD patients and healthy controls.

Main Methods:

• Structural MRI scans were acquired from 76 first-episode MDD patients and 66 healthy controls.
• Cortical thickness, surface area, and local gyrification index were calculated.
• Graph theoretical approaches were used to analyze topological properties of morphological covariance networks.

Main Results:

• Topological differences were observed exclusively in the thickness-based network.
• Patients with first-episode MDD exhibited decreased global efficiency and increased local efficiency in specific brain regions.
• Thickness-based networks in MDD patients showed more rapid disintegration under simulated targeted lesions.

Conclusions:

• A systems-level disruption in cortical thickness topology is present in first-episode MDD.
• This disruption affects network efficiency and resilience.
• These findings were specific to cortical thickness and not observed for surface area or gyrification.