Evidence from EEG of Abnormal Functional Connectivity and Microstates in GAD and PD

Panic disorder (PD) and generalized anxiety disorder (GAD) are among the most prevalent anxiety disorders (ADs), yet their neural mechanisms remain unclear. This study aimed to characterize EEG microstate patterns and their functional connectivity (FC) in patients with GAD and PD to explore the neural mechanisms underlying anxiety symptoms. Resting-state EEG was collected from 35 patients with PD, 31 patients with GAD, and 39 healthy controls (HCs). Four microstate classes (A-D) were selected to calculate the parameters, including the mean duration, time coverage, occurrence, mean global field power (GFP), and transitions. Furthermore, the FC patterns underlying each microstate class were analyzed. Correlation analyses were performed between anxiety symptoms and microstate metrics. Compared with HCs, ADs presented increased duration of microstate D and decreased time coverage of microstate A, suggesting altered neural dynamics in ADs, characterized by impaired sensory processing and executive functioning.The correlation analysis revealed that the features of microstate C (associated with self-referential processing) were positively correlated with anxiety symptoms. In contrast, the features of microstates A and B (involved in sensory network functioning) showed consistent negative correlations with anxiety symptoms. Furthermore, PD and GAD groups exhibited distinct FC patterns within microstate A. These FC differences in microstate A demonstrated potential value in distinguishing between GAD and PD.