Resting EEG source-level connectivity pattern to predict anhedonia improvement with agomelatine treatment in patients...

Neuroimaging studies have revealed that dysfunction of reward circuitry in the brain underlies anhedonia, a core symptom of major depressive disorder (MDD) that is related to treatment outcomes. However, the relationship between the brain network at the level of neuronal oscillations and the longitudinal improvement in the severity of anhedonia is still unknown.

The study enrolled 84 unmedicated patients with MDD. Anhedonia severity was measured using the Snaith-Hamilton Pleasure Scale (SHAPS). EEG data in the resting state was obtained both at baseline and following an 8-week course of agomelatine 25 mg taken once daily. Whole-brain functional connectivity (FC) of source-level resting-state EEG and FC-derived graph metrics (i.e., global topological properties: global efficiency and local efficiency) were calculated in distinct frequency bands.

SHAPS scores were significantly improved from baseline to 8 weeks. Concurrently, there was a decrease in alpha-1 (8.5-10 Hz) connectivity between the right-hemisphere precuneus (PreC) and the left-hemisphere inferior frontal gyrus (IFG). Reduced alpha-2 (10.5-12 Hz) connectivity between the right-hemisphere transverse temporal gyrus (TTG) and the left-hemisphere superior frontal gyrus (SFG) and middle frontal gyrus (MFG) was observed. Global efficiency in the alpha-1 (p < 0.001) and alpha-2 (p = 0.003) frequency bands and local efficiency in the alpha-1 frequency band (p = 0.003) were reduced. Correlation analyses showed that alpha-1 local efficiency at baseline predicted improvement in SHAPS scores (r = -0.261, p = 0.017).

Global topological properties of source-level EEG FC can predict anhedonia improvement during antidepressant treatment, which might help guide treatment decisions and advance precision psychopharmacology.