Is Connectivity in the Brain a Biomarker Signature for Depression?

Major depressive disorder (MDD) is thought to involve dysfunctional brain networks involving cortical and limbic regions. These investigators used quantitative electroencephalography (qEEG) with 35 electrodes to study functional connectivity between diverse brain regions during the resting state in 121 drug-free patients with MDD and 37 healthy controls.

Pairs of neighboring electrodes formed 66 “nodes” in the brain network, and pairs of these nodes constituted connections or “edges”; there were 2145 edges between each pair of nodes in each EEG frequency band (i.e., delta, theta, alpha, and beta bands). The researchers used weighted network analysis to map several parameters (connection strength, connection length, and overall node connectiv…