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, and to explore the neural mechanisms of anxiety symptoms through microstate analysis. Resting-state EEG was collected from 35 patients with PD, 31 patients with GAD, and 39 healthy controls (HCs). Microstate topologies (microstate-4) 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 conducted between anxiety symptoms and microstate dynamics. Compared with HCs, ADs presented an increased duration of microstate D and a decreased time coverage of microstate A. The correlation analysis revealed that the microstate C features were positively associated with anxiety symptoms. In contrast, microstate A and B exhibited consistent negative correlations with anxiety symptoms. The PD and GAD groups exhibited distinct FC patterns in microstate A. These findings reveal distinct neural dynamics in ADs characterized by impaired sensory processing and executive functioning. The abnormalities were predominantly observed in patients with GAD. Anxiety symptoms may be associated with distinct microstate patterns: positively with microstate C (linked to self-referential processing) and negatively with microstates A and B (involved in sensory network functioning). FC differences in microstate A demonstrated discriminative value for distinguishing between GAD and PD.