EEG microstate alterations in Parkinson’s disease dementia

To investigate alterations in resting-state electroencephalogram (EEG) microstates across the cognitive spectrum of Parkinson's disease (PD) and to evaluate their utility as electrophysiological biomarkers of cognitive impairment. Resting-state EEG was recorded using a 19-channel system during a 3-min eyes-closed session in 36 healthy controls (HC), 38 PD patients with normal cognition (PDNC), and 39 PD patients with dementia (PDD). Temporal parameters (duration, occurrence, coverage) of six canonical microstates (A-F) were computed and compared across groups. Correlation analyses were conducted between microstate metrics and Montreal Cognitive Assessment (MoCA) scores. Significant group differences were found in microstate dynamics. The PDD group exhibited a longer mean duration of microstates A, C, and E, and a lower occurrence per second of microstates B and C compared to both the PDNC and HC groups (all P < 0.05). Critically, the duration of microstates A and C showed significant negative correlations with MoCA scores (P < 0.05), while the occurrence of microstates B and C demonstrated positive correlations with MoCA scores (P < 0.05). Specific EEG microstate abnormalities are associated with cognitive status in PD. The prolongation of microstates A and C and the reduced occurrence of microstates B and C are stage-sensitive biomarkers that reflect the severity of cognitive decline, providing novel insights into the neural mechanisms of PD-related cognitive dysfunction.