Cognitive performance and brain structural connectome alterations in major depressive disorder.

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Major depressive disorder (MDD) is associated with cognitive dysfunction and changes in brain structural connectivity.
• The precise relationship between cognitive impairments and brain network alterations in MDD remains unclear.

Purpose of the Study:

• To investigate cognition-related structural brain networks in individuals with major depressive disorder (MDD).
• To explore the association between cognitive factors, depressive symptom severity, and structural connectivity within identified brain networks.

Main Methods:

• Assessed cognitive performance in 805 healthy and 679 MDD individuals using 14 cognitive tests.
• Reconstructed the structural connectome using MRI (structural and diffusion-weighted).
• Employed linear regressions and network-based statistics to identify cognition-related subnetworks and assess connectivity differences.

Main Results:

• All cognitive factors correlated with global connectivity strength.
• Specific subnetworks linked to cognitive factors were identified; for example, processing speed was associated with a distinct subnetwork.
• Acutely depressed patients exhibited reduced connectivity within the processing speed subnetwork compared to controls.
• Subnetwork connectivity strength correlated with current depressive symptom severity, irrespective of illness history.

Conclusions:

• This study identifies cognition-related structural brain networks in MDD for the first time.
• Findings reveal associations between cognitive deficits, depressive symptoms, and reduced structural connectivity in MDD.
• Structural connectome alterations may mediate the link between cognitive deficits and depression severity in MDD.