Band-specific features of EEG connectome in patients with early-stage Parkinson's disease

Abstract

Introduction: Parkinson’s disease (PD) is a multisystem disease, involving several brain structures. fMRI studies reported abnormal functional connectivity (FC) in PD. EEG is an accessible method to evaluate cortical activity, which may be used to estimate FC. For this aim, we analyzed differences in FC between patients at early stages of PD and healthy controls (HC) using high-density EEG (HD-EEG). Methods: We enrolled 20 early-stage PD patients and 19 age-matched HC. Data were recorded with a 64-channels HD-EEG system. A source-reconstruction method was used to identify brain-region activity. FC was calculated using a weighted phase-lag index in θ-α-β bands. Network-based statistic was used to compare FC between PD and HC. Results: No statistical-significant differences were observed in spectral analysis between groups. PD patients showed a hypoconnected network in α-band primarily composed by frontal lobe, associated with a hyperconnected network in β band, including frontal, sensorimotor, limbic and temporal areas. Moreover, correlation between β FC in sensorimotor areas and PD motor impairment was found (r = 0.80, p = 0.003). Conclusion: HD-EEG revealed FC alterations since early stages of PD, as a tool complementary to fMRI, and it could be a useful early or even preclinical diagnostic marker of disease.