Band-Specific Altered Cortical Connectivity in Early Parkinson's Disease and its Clinical Correlates

BackgroundFunctional connectivity (FC) has shown promising results in assessing the pathophysiology and identifying early biomarkers of neurodegenerative disorders, such as Parkinson's disease (PD).ObjectivesIn this study, we aimed to assess possible resting-state FC abnormalities in early-stage PD patients using high-density electroencephalography (EEG) and to detect their clinical relationship with motor and non-motor PD symptoms.MethodsWe enrolled 26 early-stage levodopa naive PD patients and a group of 20 healthy controls (HC). Data were recorded with 64-channels EEG system and a source-reconstruction method was used to identify brain-region activity. FC was calculated using the weighted phase-lag index in theta, alpha, and beta bands. Additionally, we quantified the unbalancing between beta and lower frequencies through a novel index (beta-functional ratio [FR]). Statistical analysis was conducted using a network-based statistical approach.ResultsPD patients showed hypoconnected networks in theta and alpha band, involving prefrontal-limbic-temporal and frontoparietal areas, respectively, and a hyperconnected network in the beta frequency band, involving sensorimotor-frontal areas. The theta FC network was negatively related to Non-Motor Symptoms Scale scores and alpha FC to the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale part III gait subscore, whereas beta FC and beta-FR network were positively linked to the bradykinesia subscore. Changes in theta FC and beta-FR showed substantial reliability and high accuracy, precision, sensitivity, and specificity in discriminating PD and HC.ConclusionsFrequency-specific FC changes in PD likely reflect the dysfunction of distinct cortical networks, which occur from the early stage of the disease. These abnormalities are involved in the pathophysiology of specific motor and non-motor PD symptoms, including gait, bradykinesia, mood, and cognition. (c) 2023 International Parkinson and Movement Disorder Society.

Automated summary

This study investigates the resting-state functional connectivity (FC) abnormalities in early-stage Parkinson's disease (PD) patients using high-density electroencephalography (EEG). The findings suggest that frequency-specific FC changes in PD are associated with motor and non-motor symptoms, reflecting dysfunction in distinct cortical networks from the early stage of the disease.