EEG microstates in adolescent depression: Effects of depression severity and overall symptoms.

Electroencephalogram (EEG) microstates are emerging as potential biomarkers for major depressive disorder (MDD), yet their characteristics in adolescent MDD with varying depression and anxiety severity remain underexplored. This study investigated the relationship between EEG microstate dynamics and symptom severity in 65 adolescents diagnosed with MDD. We assessed symptom severity using the Self-Rating Depression Scale (SDS), Self-Rating Anxiety Scale (SAS), and Symptom Checklist-90 (SCL-90). Resting-state EEG data were recorded for 5 min (eyes closed) using a 64-channel system and analyzed via microstate analysis with k-means clustering. Four microstates (A, B, C, D) were identified. Compared to adolescents with mild to moderate MDD (MMDD), those with severe MDD (SMDD) exhibited reduced occurrence and duration of microstate C and increased duration of microstate D. Weak but significant correlations were observed between symptom severity (SDS and SCL-90 scores) and microstate parameters, including occurrence and coverage of microstate C and transition probabilities between microstates A and D. These findings deepen our understanding of MDD's pathophysiological mechanisms and highlight the influence of symptom severity on EEG microstate abnormalities in adolescents.