White Matter Tract Alterations in Drug-Naïve Parkinson's Disease Patients With Excessive Daytime Sleepiness.

Amir Ashraf-Ganjouei,Maryam Masoudi,Bahram Mohajer,Mahtab Mojtahed Zadeh,Ghazaleh Kheiri,Mehdi Shirin Shandiz,Mohammad Hadi Aarabi,Pejman Saberi

doi:10.3389/fneur.2019.00378

Abstract

Excessive daytime sleepiness (EDS) is relatively frequent in patients with Parkinson's disease (PD), having a prominent burden on patients' quality of life and causing dangerous events such as motor-vehicle accidents. Previous studies have indicated the role of certain neural tracts in the pathophysiology of sleep disturbances, especially in PD patients. We hypothesized that white matter integrity and connectivity might be altered in patients with PD and EDS. Therefore, this study investigated brain white matter microstructure alterations in patients with Parkinson's disease with EDS (PD-EDS) compared to healthy controls and PD patients without EDS (PD-nEDS). Diffusion MRI connectometry was used to carry out group analysis between PD patients with and without EDS and healthy individuals. EDS in PD patients is associated with decreased connectivity in the left and right fornix, left and right inferior longitudinal fasciculus (ILF), left inferior and middle cerebellar peduncles in comparison to PD-nEDS group. These differences between PD-EDS and PD-nEDS patients reflects microstructural changes with respect to sleep-related circuits, which can pave the way for future investigations considering EDS pathogenesis in Parkinson's disease.

Highlights

Non-motor symptoms in Parkinson’s disease (PD) have been given more attention during recent years, mainly due to their massive burden on patients’ quality of life [1, 2]
PD-Excessive daytime sleepiness (EDS) Patients vs. PD-nEDS Patients Compared with PD-nEDS patients, Parkinson’s disease with EDS (PD-EDS) patients showed decreased connectivity in left and right fornix, left, and right inferior longitudinal fasciculus (ILF), middle cerebellar peduncle and left inferior cerebellar peduncle (FDR = 0.021978) (Figure 1)
The differences were that connectivity in HC was higher than that in PD-EDS patients in the left inferior fronto-occipital fasciculus, the left ILF, the body of the corpus callosum, the splenium, the left corticospinal tract (CST) and the right cingulum (FDR = 0.0383761)

Summary

Introduction

Non-motor symptoms in Parkinson’s disease (PD) have been given more attention during recent years, mainly due to their massive burden on patients’ quality of life [1, 2]. Affecting up to 60% of PD patients, excessive daytime sleepiness (EDS) is characterized by inappropriate sleepiness during the waking time. It could be present anytime in the course of PD, even before the appearance of the motor symptoms [3,4,5] and be regarded as a risk factor for the development of neurodegenerative diseases in future [6]. A longitudinal study revealed that the presentation of EDS progresses throughout the course of the disease from 4 to 41% in 8 years [7]. Multiple factors are supposed to be associated with the prevalence of EDS including age, sex, presence of rapid eye movement (REM) sleep behavior disorder (RBD), mood disorders and cognitive impairment [5, 8,9,10].

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