Altered electroencephalographic microstate dynamics in major depressive disorder and their modulation by melatonergic...

The modulation of brain dynamics by melatonin antidepressants in patients with major depressive disorder (MDD) remains unclear.

Resting-state electroencephalographic (EEG) was recorded in 84 drug-free patients with MDD and 143 healthy controls. EEG data were collected at baseline and after 8-week agomelatine treatment. K-means clustering identified four canonical microstates (MS-A-D), and topographic analysis of variance assessed group differences.

At baseline, patients with MDD showed increased occurrence and coverage of MS-C and MS-D, along with a higher transition probability between these two states, compared to healthy controls. In contrast, the duration and coverage of MS-A and MS-B, as well as their transition probabilities, were reduced in the MDD group. Following treatment, patients with MDD exhibited increased MS-A coverage and a higher transition probability from MS-A to MS-B, while the transition probability between MS-C and MS-D decreased. Several microstate parameters were normalized to those of healthy controls. Notably, MS-B occurrence negatively correlated with baseline anhedonia severity, although no microstate measures predicted changes in anhedonia over time.

This study demonstrates altered EEG microstate dynamics in patients with MDD and provides insights into the neural mechanisms underlying MDD. Microstate abnormalities may serve as potential clinical biomarkers for MDD.