Clinical Characteristics, Iron Metabolism and Neuroinflammation: New Insight into Excessive Daytime Sleepiness in Parkinson’s Disease

Abstract

Yang Hu,1 Peng Guo,1 Teng-Hong Lian,1 Li-Jun Zuo,1 Shu-Yang Yu,1 Li Liu,2 Zhao Jin,1 Qiu-Jin Yu,1 Rui-Dan Wang,1 Li-Xia Li,2 Ying-Shan Piao,3 Wei Zhang3– 7 1Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, People’s Republic of China; 2Department of Internal Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, People’s Republic of China; 3Center for Cognitive Neurology, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, People’s Republic of China; 4China National Clinical Research Center for Neurological Diseases, Beijing, 100070, People’s Republic of China; 5Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100069, People’s Republic of China; 6Center of Parkinson’s Disease, Beijing Institute for Brain Disorders, Beijing, 100053, People’s Republic of China; 7Beijing Key Laboratory on Parkinson’s Disease, Beijing, 100053, People’s Republic of ChinaCorrespondence: Wei ZhangCenter for Cognitive Neurology, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, People’s Republic of ChinaTel [phone]Fax [phone]Email [email protected]: To investigate the clinical characteristics, iron metabolism and neuroinflammation in Parkinson’s disease (PD) patients with excessive daytime sleepiness (EDS).Methods: We studied 379 patients with PD and 30 age-matched controls. All subjects were evaluated by Epworth sleepiness scale (ESS) and a series of rating scales and were divided into PD-EDS and PD-NEDS groups according to ESS score. The concentrations of iron and iron-related proteins and inflammatory cytokines in both cerebrospinal fluid (CSF) and serum were examined.Results: 1. The occurrence rate of EDS in total PD patients was 16.09%. 2. PD-EDS group had significantly severer disease stages, more severe motor and non-motor features of the disease. 3. In CSF, the concentrations of iron and IL-1β in the PD-EDS group were significantly higher and ferritin concentration was prominently lower when compared with the PD-NEDS group and the control group; ESS score was significantly associated with high concentrations of iron and IL-1β and low concentration of ferritin in the PD group. Iron concentration was positively correlated with IL-1β concentration in the PD-EDS group. 4. In serum, no changes were observed in iron and iron-related proteins and inflammatory cytokines among the three groups.Conclusion: EDS was a common symptom in PD patients. PD patients with EDS had more severe motor and some non-motor symptoms. Overloaded iron-relevant inflammation in the brain might be an underlying mechanism of PD-EDS.Keywords: Parkinson disease, excessive daytime sleepiness, clinical features, iron metabolism, inflammation

Keywords

• parkinson disease
• excessive daytime sleepiness
• clinical features
• iron metabolism
• inflammation