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Disturbed phase relations in white matter hyperintensity based vascular dementia: an EEG directed connectivity study
E C W van Straaten1, J den Haan2, H de Waal3
1Department of Clinical Neurophysiology, VU University Medical Center, Amsterdam, The Netherlands; Nutricia Advanced Medical Nutrition, Danone Research, Centre for Specialised Nutrition, Wageningen, The Netherlands.
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.
Significance:
Structural damage at the regions of long distance white matter tracts may induce changes in the direction of phase relationships of distinct brain regions.
Insights
Vascular dementia patients with white matter hyperintensities exhibit disrupted brain connectivity patterns. This study reveals altered directional brain signal flow in these patients compared to healthy controls.
Area of Science:
- Neuroscience
- Medical Imaging
- Cognitive Neurology
Background:
- White matter hyperintensities (WMH) on MRI are linked to small vessel disease and vascular dementia (WMH-VaD).
- WMH-VaD is characterized by executive dysfunction and slowed processing speed, potentially due to reduced cerebral blood flow.
- Investigating functional brain differences in WMH-VaD patients is crucial for understanding disease mechanisms.
Purpose of the Study:
- To compare functional brain connectivity patterns between patients with WMH-VaD and non-demented controls.
- To explore differences in directed functional connectivity (dPLI) and its relationship with cognitive performance.
Main Methods:
- Resting-state encephalography (EEG) was performed on 17 WMH-VaD patients and 17 controls.
- Phase Lag Index (PLI) and directed Phase Lag Index (dPLI) were used to analyze functional connectivity across delta, theta, alpha, and beta frequency bands.
- Cognitive test performance was correlated with connectivity measures.
Main Results:
- No significant difference in mean undirected functional connectivity (PLI) was observed between groups.
- Controls exhibited a distinct anterior-to-posterior phase gradient in dPLI across most frequency bands.
- WMH-VaD patients showed a significantly disrupted directional connectivity pattern without a clear anterior-to-posterior gradient.
Conclusions:
- Non-demented individuals display a clear front-to-back direction of brain connectivity.
- This directional connectivity pattern is disturbed in patients with vascular dementia and extensive white matter hyperintensities.
- Damage to white matter tracts may underlie the observed alterations in phase relationships between brain regions.
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