Increased Activation of Default Mode Network in Early Parkinson’s With Excessive Daytime Sleepiness

Abstract

Background and Objectives: The underlying neuropathology of excessive daytime sleepiness (EDS) remains elusive in Parkinson's disease (PD). We aim to investigate neural network changes that underlie EDS in PD.Methods: Early PD patients comprising eighty-one patients without EDS (EDS−) and seventeen patients with EDS (EDS+) received a resting state functional MRI scan and the Epworth Sleepiness Scale (ESS). Connectivities within the default mode network (DMN), motor and basal ganglia networks were compared between the EDS+ and EDS− groups. Correlations between network connectivity and the severity of EDS were investigated through linear regression.Results: EDS+ patients displayed a trend of increased network connectivity of the posterior DMN (pDMN). A significant positive correlation was found between connectivity of the ventromedial prefrontal cortex in the pDMN and ESS.Conclusion: EDS+ patients are likely to display increased activation in the DMN, suggesting neural compensation in early PD or impaired attentiveness due to mechanisms such as mind-wandering.

Pharmacological and Non-pharmacological Treatments of Sleep Disorders in Parkinson's Disease

“…It is also regarded as a marker of widespread neurodegeneration in some studies [ 57 ]. Functional imaging studies found PD patients with EDS displayed a trend of increased network connectivity of the posterior default mode network, which was also related to mind-wandering [ 122 ]. Many studies have demonstrated that EDS is associated with older age, male, advanced motor impairment, hallucinations, depression, anxiety and longer disease duration in PD patients [ 32 , 123 ].…”

Altered dynamic functional network connectivity in drug-naïve Parkinson’s disease patients with excessive daytime sleepiness

“…As a key function of the BG, the disruption of striatal neuron signaling may facilitate the occurrence of EDS symptoms in PD patients. In early PD patients, Ooi et al showed that BG connectivity was positively correlated with ESS scores, which suggested the existence of compensatory mechanisms in early PD patients ( Ooi et al, 2019 ). The CB may also be associated with EDS symptoms in PD patients.…”

“…Functional connectivity analysis can be used to evaluate correlations and synchronization at brain regions and the whole brain network levels. Multiple studies have demonstrated that EDS in PD patients may be associated with abnormal functional connectivity among various brain regions, including the default mode network (DMN), cognitive executive network (CEN), salience network (SN) and cerebellum (CB) ( Wen et al, 2016 ; Ooi et al, 2019 ; Wang et al, 2020 ; Zi et al, 2022 ; Zheng et al, 2023 ). However, these static rs-fMRI data were measured under the assumption that the intrinsic fluctuations during MRI scans are stationary, ignoring the temporal dynamic properties of functional connectivity.…”

Abnormalities in the Fractional Amplitude of Low-Frequency Fluctuation and Functional Connectivity in Parkinson's Disease With Excessive Daytime Sleepiness

“…For example, some researchers proposed that there is an inverse relationship between EDS and the functional connection between thalamocortex and DMN (Killgore et al, 2015 ), and EDS is related to decreased DMN connectivity in young people and elderly people with intact cognition (Ward et al, 2013 ). A recent study reported a positive relationship between the occurrence of EDS and DMN network connectivity in patients with early PD-EDS, suggesting a compensatory mechanism in the early stage of the disease (Ooi et al, 2019 ). The results of this study also support the view that the occurrence of EDS is related to abnormal changes in DMN.…”