title: Cognitive dysfunction in early multiple sclerosis: altered centrality derived from resting-state functional connectivity using magneto-encephalography.
abstract: BACKGROUND
  Cognitive dysfunction in multiple sclerosis (MS) is frequent. Insight into underlying mechanisms would help to develop therapeutic strategies.
  
  
  OBJECTIVE
  To explore the relationship of cognitive performance to patterns of nodal centrality derived from magneto-encephalography (MEG).
  
  
  METHODS
  34 early relapsing-remitting MS patients (median EDSS 2.0) and 28 age- and gender-matched healthy controls (HC) had a MEG, a neuropsychological assessment and structural MRI. Resting-state functional connectivity was determined by the synchronization likelihood. Eigenvector Centrality (EC) was used to quantify for each sensor its connectivity and importance within the network. A cognition-score was calculated, and normalized grey and white matter volumes were determined. EC was compared per sensor and frequency band between groups using permutation testing, and related to cognition.
  
  
  RESULTS
  Patients had lower grey and white matter volumes than HC, male patients lower cognitive performance than female patients. In HC, EC distribution showed highest nodal centrality over bi-parietal sensors ("hubs"). In patients, nodal centrality was even higher bi-parietally (theta-band) but markedly lower left temporally (upper alpha- and beta-band). Lower cognitive performance correlated to decreased nodal centrality over left temporal (lower alpha-band) and right temporal (beta-band) sensors, and to increased nodal centrality over right parieto-temporal sensors (beta-band). Network changes were most pronounced in male patients.
  
  
  CONCLUSIONS
  Partial functional disconnection of the temporal regions was associated with cognitive dysfunction in MS; increased centrality in parietal hubs may reflect a shift from temporal to possibly less efficient parietal processing. To better understand patterns and dynamics of these network changes, longitudinal studies are warranted, also addressing the influence of gender.
authors: Department of Clinical Neurophysiology, VU University Medical Center, Amsterdam, The Netherlands. mhardmeier@uhbs.ch
authors: Martin
authors: M
authors: Hardmeier
authors: Menno M
authors: MM
authors: Schoonheim
authors: Jeroen J G
authors: JJ
authors: Geurts
authors: Arjan
authors: A
authors: Hillebrand
authors: Chris H
authors: CH
authors: Polman
authors: Frederik
authors: F
authors: Barkhof
authors: Cornelis J
authors: CJ
authors: Stam
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000150:complications / Q000473:pathology* / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D009103:Multiple Sclerosis / Q000150:complications; D009415:Nerve Net / Q000473:pathology* / Q000503:physiopathology*; D009483:Neuropsychological Tests; D012146:Rest