title: Disturbed phase relations in white matter hyperintensity based vascular dementia: an EEG directed connectivity study.
abstract: OBJECTIVE
  White matter hyperintensities (WMH), a feature seen on magnetic resonance imaging (MRI) and regarded to reflect small vessel disease, can lead to vascular dementia (WMH-VaD). In WMH-VaD, cognitive deficits typically consist of executive function disturbances, and reduced information processing speed, regarded as a result of cerebral hypoperfusion. We aimed to investigate whether this patient group has typical functional differences from controls.
  
  
  METHODS
  Resting-state encephalography studies of 17 VaD patients and 17 age- and gender matched non-demented controls were analysed in the delta, theta, alpha1 and 2, and beta frequency bands. Undirected functional connectivity between electrodes was established with the Phase Lag Index (PLI) and directed functional connectivity with the directed Phase Lag Index (dPLI). PLI and dPLI were related to performance in cognitive testing.
  
  
  RESULTS
  Mean PLI did not differ between patients and controls. In the control group dPLI showed anterior to posterior phase gradients in all bands except the delta band. In the VaD patient group this pattern was significantly different without a clear directional pattern. No relationship with cognition was demonstrated.
  
  
  CONCLUSIONS
  This study shows a clear front-to-back direction of connectivity in non-demented controls. In VaD patients with extensive WMH, this pattern is disturbed.
  
  
  CONCLUSIONS
  Structural damage at the regions of long distance white matter tracts may induce changes in the direction of phase relationships of distinct brain regions.
authors: Department of Clinical Neurophysiology, VU University Medical Center, Amsterdam, The Netherlands; Nutricia Advanced Medical Nutrition, Danone Research, Centre for Specialised Nutrition, Wageningen, The Netherlands. Electronic address: i.vanstraaten@vumc.nl.
authors: E C W
authors: EC
authors: van Straaten
authors: Department of Clinical Neurophysiology, VU University Medical Center, Amsterdam, The Netherlands.
authors: J
authors: J
authors: den Haan
authors: Alzheimer Center at Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors: H
authors: H
authors: de Waal
authors: Alzheimer Center at Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands; Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
authors: W M
authors: WM
authors: van der Flier
authors: Department of Radiology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.
authors: F
authors: F
authors: Barkhof
authors: Alzheimer Center at Department of Neurology, VU University Medical Center, Amsterdam, The Netherlands.
authors: N D
authors: ND
authors: Prins
authors: Department of Clinical Neurophysiology, VU University Medical Center, Amsterdam, The Netherlands.
authors: C J
authors: CJ
authors: Stam
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D003071:Cognition; D015140:Dementia, Vascular / Q000473:pathology / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology*; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D066127:White Matter / Q000473:pathology / Q000503:physiopathology*
keywords: Directed phase lag index; EEG; Functional connectivity; Phase Lag Index; Vascular dementia; WMH