Alterations of the brain network in idiopathic rapid eye movement sleep behavior disorder: structural connectivity analysis
To evaluate and compare structural connectivity using graph theoretical analysis in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) and healthy subjects.
Ten consecutive patients with iRBD were recruited from a single tertiary hospital. All patients had normal brain magnetic resonance imaging results on visual inspection. They did not have any other neurological disorder. Control subjects were also enrolled. All subjects underwent three-dimensional volumetric T1-weighted imaging. Absolute structural volumes were calculated using FreeSurfer image analysis software. Structural volume and connectivity analyses were performed with Brain Analysis using Graph Theory.
Compared to healthy controls, patients with iRBD showed significant alterations in cortical and subcortical volumes, showing increased volumes of frontal cortex, thalamus, and caudate nucleus. In addition, patients with iRBD exhibited significantly different structural connectivity compared to healthy controls. In measures of global network, average degree, global efficiency, and local efficiency were decreased whereas characteristic path length was increased in iRBD patients. In measures of local network, there was significant hub reorganization in patients with iRBD. Betweenness centrality of caudate nucleus and frontal cortex was increased in patients with iRBD.
This is the first study to report that structural volume and connectivity in patients with iRBD are significantly different from those in healthy controls. iRBD patients exhibited disrupted topological disorganization of the global brain network and hub reorganization. These alterations are implicated in the pathogenesis of iRBD. They might be potential biomarkers of iRBD.
KeywordsREM sleep behavior disorder Graph theory Network Magnetic resonance imaging
This study was supported by a grant (NRF-2017R1C1B5015871) of the National Research Foundation (NRF) funded by the Ministry of Science and ICT, Republic of Korea. The funding agency had no role in the study design or conduct of this research.
Compliance with ethical standards
Conflicts of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with ethical standards of the institutional and/or national research committee, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Formal consent was not required for a study of this type.
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