Introduction

Previous studies showed that slowing of electroencephalographic (EEG) and magnetoencephalographic (MEG) waves assessed by power spectral density (PSD) may be related to cognitive decline in Parkinson’s disease (PD) patients.1–3 Multimodal studies evaluating associations between PD-specific neuroimaging and neurophysiological biomarkers in revealing executive dysfunction mechanisms in PD are scarce, and especially in studying the association of resting state brain waves (PSD-EEG) with the dopaminergic function imaging methods. Currently, a gold standard diagnostic tool in PD is positron emission computed tomography (PET/CT), particularly using the PD-specific radiotracer, e.g., the [18F]Fluorodopa ([18F]FDOPA) uptake ratio in the striatum, which reflects dopaminergic deficiency in idiopathic PD patients.4–7 Multimodal studies with usage of the PET/CT, EEG and behavioral testing may have scientific relevance in an understanding of neural mechanisms in PD-related executive dysfunction, but also they may be of great practical importance for PD diagnosis.
Hence, our study aimed to (i) compare the values of resting state PSD-EEG, striatal [18F]FDOPA PET/CT uptake and neuropsychological cognitive testing parameters between mild PD patients and healthy controls, as well as (ii) to evaluate associations between these outcomes. Additional aim was to estimate PD diagnostic accuracy (with receiver operating characteristic [ROC] curves) of the PSD-EEG parameters in reference to the gold diagnostic standard of the striatal [18F]FDOPA PET/CT uptake ratio.
According to the “dual hypothesis”,8 assuming the dopaminergic-mediated striatofrontal executive dysfunction in early-stage PD, we hypothesized that values of (i) the PSD-EEG, striatal [18F]FDOPA PET/CT uptake ratio and neuropsychological parameters would differ between mild PD patients and healthy controls and (ii) that the PD-specific neuroimaging findings (increased PSD-EEG alpha- and theta- waves and decreased striatal [18F]FDOPA PET/CT uptake ratio) would be correlated to each other and with neuropsychological outcomes reflecting executive dysfunction.