Restless legs syndrome in Parkinson disease: Clinical characteristics, abnormal iron metabolism and altered neurotransmitters

Ying-Shan Piao,Li Liu,Xiao-Min Wang,Yang Hu,Li-Xia Li,Hui Zhao,Teng-Hong Lian,Rui-Dan Wang,Wei Zhang,Qiu-Jin Yu,Li-Jun Zuo,Sheng-Di Chen,Piu Chan,Peng Guo,Shu-Yang Yu,Zhao Jin

doi:10.1038/s41598-017-10593-7

Abstract

Relationships among clinical characteristics, iron metabolism and neurotransmitters in Parkinson disease (PD) patients with restless legs syndrome (RLS) remains unclear. We divided 218 patients into PD with and with no RLS (PD-RLS and PD-NRLS) groups by RLS-rating scale (RLS-RS) score. Motor and non-motor symptoms were rated by related scales. Iron and related proteins, and neurotransmitters in cerebrospinal fluid (CSF) and serum were measured. PD-RLS frequency was 40.37%. PD-RLS group had longer duration, higher stage and scores of motor symptoms, depression, anxiety, sleep disorders, fatigue and apathy, and increased transferrin and decreased iron, ferritin, dopamine (DA) and 5-hydroxytryptamine (5-HT) in CSF. In CSF of PD-RLS group, RLS-RS score was positively correlated with transferrin level and negatively correlated with iron and ferritin levels; RLS-RS score was negatively correlated with DA and 5-HT levels; transferrin level was negatively correlated with DA and 5-HT levels, and ferritin level was positively correlated with DA level. In serum, PD-RLS group had decreased iron and transferrin levels, which were negatively correlated with RLS-RS score. PD-RLS was common and severer in motor and some non-motor symptoms. Iron deficiency induced by its metabolism dysfunctions in peripheral and central systems might cause PD-RLS through decreasing brain DA and 5-HT.

Highlights

Parkinson disease (PD) is a common neurodegenerative disease in the elderly population with motor symptoms, including bradykinesia, resting tremor, rigidity and postural and gait instability
In PD-restless legs syndrome (RLS) patients, how are the levels of iron and related proteins changed in brain? Currently, few studies have detected the levels of iron and related proteins in cerebrospinal fluid (CSF) and serum, and no investigation has focused on the correlation between RLS and iron metabolism in peripheral and central nervous systems in PD patients
Comparison of levodopa equivalent daily dose revealed that PD with RLS (PD-RLS) group used higher dose of dopaminergic drugs than PD with no RLS (PD-NRLS) group (Table 2)

Summary

Introduction

Parkinson disease (PD) is a common neurodegenerative disease in the elderly population with motor symptoms, including bradykinesia, resting tremor, rigidity and postural and gait instability. RLS is found to be an independent factor affecting sleep quality, and seriously compromises quality of life for PD patients[2] It is not well known about the clinical characteristics of RLS, the relationship between RLS and motor symptoms or other non-motor symptoms of PD yet. Both PD and RLS are related to abnormal iron metabolism by the increasing investigations. We investigated the clinical characteristics of RLS, the relationship between RLS and motor symptoms or other non-motor symptoms, and explored the potential mechanism involving abnormal iron metabolism and altered neurotransmitters

Methods

Results

Conclusion