Abstract
Early differentiation of bipolar disorder (BD) from major depressive disorder (MDD) in adolescents remains clinically challenging due to overlapping symptom presentations. This study employed resting-state electroencephalography (rsEEG) functional connectivity analysis, integrating EEG source imaging and k-means clustering, to identify neurophysiological biomarkers that differentiate BD and MDD. A total of 54 adolescents participated in the study including 24 with BD (including five diagnostically ambiguous MDD-BD converters) and 30 with MDD. We identified distinct rsEEG brain states by clustering method, that significantly differentiated the two groups. Importantly, baseline EEG patterns of the MDD-BD converters closely resembled those observed in BD. These results suggest that rsEEG functional connectivity offer objective biomarkers for distinguishing BD from MDD at baseline EEG data.