Electroencephalography microstates detect early cognitive impairment in Parkinson's disease

The management of cognitive disorders associated with Parkinson's disease (PD) requires early diagnosis. Due to its advantages, including accessibility and millisecond temporal resolution, electroencephalography (EEG), has been widely investigated. However, it has so far have only enabled the detection of mild to severe stage of cognitive impairment. In this study, we explored EEG microstates analysis as a method for detecting early-stage cognitive impairment. Three groups of PD patients were included: those with normal cognition (NC), patients with slight mental slowing (Pre_MCI), and patients with mild cognitive impairment (MCI). All underwent high-density, eyes-closed, resting-state EEG recordings. Microstates parameters were derived from the signal and compared across groups. A four-states configuration (labelled A, B, C and D) was identified in all patients, explaining 82% of signal variability. The duration and time coverage of microstate A were significant greater in both the Pre_MCI and the MCI groups compared to the cognitively intact group. Moreover, time coverage of microstate D was higher in the Pre-MCI group than in the MCI group. To date, EEG microstates analysis has mainly been used to explore underlying physiological mechanisms. Our findings show that it may also yield measurable indicators suitable as biomarkers, with potential clinical applicability. The next step is to validate this approach in PD patients with subjective cognitive decline who do not yet present objective deficits in comprehensive neuropsychological assessment.