title: Loss of EEG Network Efficiency Is Related to Cognitive Impairment in Dementia With Lewy Bodies.
abstract: OBJECTIVE
  The aim of this study was to test whether disturbed EEG resting-state functional connectivity and network organization are a potential neurophysiological substrate of cognitive impairment in dementia with Lewy bodies.
  
  
  METHODS
  EEG recordings were obtained in dementia with Lewy bodies patients, Alzheimer's disease patients and controls, matched for age and sex (N = 66 for each group; 14 [21%] female; mean age: 70 years). We analyzed functional connectivity of band-filtered EEG time series using the phase lag index. Functional brain network topology was analyzed with the minimum spanning tree. Mini-Mental State Examination, Trail Making Test A, and Visual Association Test were used as cognitive measures.
  
  
  RESULTS
  Dementia with Lewy bodies patients showed lower connectivity strength in the alpha frequency band, compared to both controls and Alzheimer's disease patients (P < 0.001). Functional network topology in dementia with Lewy bodies patients was less efficient and contained less hubs (P < 0.01). Network characteristics in Alzheimer's disease patients were in between (but did not differ from) those of the other two groups. In dementia with Lewy bodies patients, lower alpha band phase lag index correlated with Visual Association Test scores and Trail Making Test scores (ρ = 0.33 and ρ = 0.31, respectively), whereas leaf fraction (a measure of 'network efficiency') correlated with Visual Association Test scores (ρ = 0.29) and Mini-Mental State Examination scores (ρ = 0.27).
  
  
  CONCLUSIONS
  Functional networks of dementia with Lewy bodies patients are characterized by decreased connectivity strength and a loss of network efficiency and hubs. Severity of these disturbances is related to cognitive impairment, suggesting that network disturbances mediate between neuropathology and the clinical syndrome in dementia with Lewy bodies.
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.|Department of Clinical Neurophysiology and MEG Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.|Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.|Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Edwin
authors.initials: E
authors.lastname: van Dellen
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Hanneke
authors.initials: H
authors.lastname: de Waal
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.|Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Wiesje M
authors.initials: WM
authors.lastname: van der Flier
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Afina W
authors.initials: AW
authors.lastname: Lemstra
authors.affiliation: Department of Intensive Care Medicine, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Arjen J C
authors.initials: AJ
authors.lastname: Slooter
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Lieke L
authors.initials: LL
authors.lastname: Smits
authors.affiliation: Department of Clinical Neurophysiology and MEG Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Elisabeth C W
authors.initials: EC
authors.lastname: van Straaten
authors.affiliation: Department of Clinical Neurophysiology and MEG Center, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Stam
authors.affiliation: Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Philip
authors.initials: P
authors.lastname: Scheltens
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000209:etiology* / Q000473:pathology*; D004569:Electroencephalography; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D020961:Lewy Body Disease / Q000150:complications*; D008297:Male; D016571:Neural Networks, Computer; D009434:Neural Pathways / Q000503:physiopathology*; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales
keywords: Minimum Spanning Tree; cognitive impairment; dementia with Lewy Bodies; electroencephalography; functional connectivity