Resting-state quantitative electroencephalography reveals increased neurophysiologic connectivity in depression

Area of Science:

• Neuroscience
• Psychiatry
• Computational Biology

Background:

• Major Depressive Disorder (MDD) is associated with brain network dysfunction.
• Previous studies used functional imaging, but neurophysiologic connectivity in MDD remains underexplored.

Purpose of the Study:

• To investigate resting-state functional connectivity using quantitative electroencephalography (qEEG) coherence in unmedicated MDD patients.
• To identify differences in brain network characteristics between MDD subjects and healthy controls.

Main Methods:

• Weighted network analysis of qEEG coherence in 121 unmedicated MDD subjects and 37 healthy controls.
• Examination of coherence across delta, theta, alpha, and beta frequency bands.
• Identification of hub nodes and analysis of connection distances and regional involvement.

Main Results:

• MDD subjects exhibited significantly higher overall coherence across all examined frequency bands (delta, theta, alpha, beta).
• Increased long-range theta and alpha coherence were observed between frontopolar and temporal/parietooccipital regions in MDD.
• Increased beta coherence was found within and between dorsolateral prefrontal cortical (DLPFC) and temporal regions in MDD.
• MDD was characterized by six specific alpha band connections, predominantly involving the prefrontal cortex.

Conclusions:

• Resting-state functional connectivity in MDD shows a loss of selectivity, characterized by increased overall coherence.
• Findings provide a new framework for interpreting prior studies on frontal alpha activity in MDD.
• Results support the potential of qEEG measures for developing state and trait biomarkers for MDD.