Disturbed phase relations in white matter hyperintensity based vascular dementia: an EEG directed connectivity study.

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.