How does white matter microstructure differ between the vascular and amnestic mild cognitive impairment?

Area of Science:

• Neuroimaging
• Neuroscience
• Neurology

Background:

• White matter (WM) microstructure changes are implicated in cognitive impairment.
• Differences in WM microstructure between vascular mild cognitive impairment (VaMCI) and amnestic mild cognitive impairment (aMCI) are not well understood.

Purpose of the Study:

• To investigate and compare white matter microstructure in patients with VaMCI and aMCI.
• To explore the relationship between white matter integrity and memory performance in these two pre-dementia subtypes.

Main Methods:

• Diffusion MRI (dMRI) was used to quantify WM microstructure parameters: fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AxD), and radial diffusivity (RD).
• Tract-based spatial statistics (TBSS) compared dMRI parameters between 28 VaMCI and 34 aMCI patients, controlling for age, gender, and education.
• Neuropsychological tests, including the Auditory Verbal Learning Test (AVLT), assessed cognitive function.

Main Results:

• No significant differences in overall FA, MD, AxD, or RD were found between the VaMCI and aMCI groups.
• Significant differences emerged in the correlation between FA and AVLT performance.
• VaMCI showed a positive correlation between FA and AVLT scores (R = 0.64, P < 0.001), primarily in the corona radiata and corpus callosum.
• aMCI exhibited an opposite trend, with a negative correlation between FA and AVLT scores (R = -0.34, P = 0.047).

Conclusions:

• Early-stage VaMCI and aMCI exhibit similar white matter microstructure patterns.
• The distinct relationships between white matter integrity and memory performance suggest divergent neuropathological mechanisms underlying cognitive deficits in VaMCI and aMCI.