Altered functional connectivity in idiopathic rapid eye movement sleep behavior disorder: A resting-state EEG study

Jun Sang Sunwoo, Sanghun Lee, Jung Hoon Kim, Jung Ah Lim, Tae Joon Kim, Jung Ick Byun, Min Hee Jeong, Kwang Su Cha, Jeong Woo Choi, Kyung Hwan Kim, Soon Tae Lee, Keun Hwa Jung, Kyung Il Park, Kon Chu, Manho Kim, Sang Kun Lee, Ki Young Jung

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15 Citations (Scopus)

Abstract

Study Objectives: Idiopathic rapid eye movement sleep behavior disorder (iRBD) is considered as a prodromal stage of synucleinopathy. Although loss of functional connectivity is implicated in neurodegenerative diseases, network characteristics of electroencephalography (EEG) in iRBD are unknown. Therefore, we evaluated resting-state EEG functional connectivity to identify the brain network changes in patients with iRBD. Methods: We prospectively enrolled 20 patients with polysomnography-confirmed iRBD and 16 controls. Four patients with mild cognitive impairment were excluded from the analysis after cognitive function tests. EEG was recorded during relaxed wakefulness. We computed the weighted phase lag index as a measure of functional connectivity from EEG recordings. Results: All patients with iRBD (mean age 64.3 years; men, 68.8%) had no overt manifestations of neurodegenerative diseases such as Parkinsonism or dementia. The mean duration from symptom onset was 4.8 years. Overall connectivity strength did not differ between the two groups in all frequency bands. However, comparisons of each functional connection with the nonparametric permutation test demonstrated iRBD had decreased delta-band functional connectivity in the frontal regions. There were no significantly increased functional connections in all frequencies. The altered connections had a significant correlation with RBD questionnaire scores. Notably, delta-band weighted phase lag index between left frontal and central regions was correlated with verbal fluency performance (r = 0.486, p = .007). Conclusions: Resting-state brain network of iRBD was characterized by a loss of delta-band functional connectivity. Therefore, functional networks in iRBD are altered at the early phase of disease.

Original languageEnglish
JournalSleep
Volume40
Issue number6
DOIs
Publication statusPublished - 2017 Jun

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2014R1A2A2A04003858).

All Science Journal Classification (ASJC) codes

  • Clinical Neurology
  • Physiology (medical)

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