White matter hyperintensity microstructure in amyloid dysmetabolism

Area of Science:

• Neuroscience
• Neuropathology
• Medical Imaging

Background:

• Cerebrovascular disease (CVD) and Alzheimer's disease (AD) are increasingly linked.
• White matter hyperintensities (WMHs) are common in mild cognitive impairment (MCI) and AD, but their precise connection to AD pathology is unclear.

Purpose of the Study:

• To investigate the impact of amyloid dysmetabolism on the white matter microstructure of WMHs.
• To explore the relationship between amyloid-β peptide (Aβ) levels and diffusion tensor imaging (DTI) metrics in WMHs.

Main Methods:

• Studied 51 subjects with MCI or subjective cognitive decline, divided into amyloid-β positive (Aβ+) and negative (Aβ-) groups based on cerebrospinal fluid (CSF) Aβ42 levels.
• Utilized magnetic resonance diffusion tensor imaging (DTI) to assess fractional anisotropy (FA), radial diffusivity (DR), axial diffusivity (DA), and mean diffusivity (MD) in WMHs.
• Analyzed WMH volume and distribution, and the influence of age and WMH volume on DTI indices.

Main Results:

• No significant differences in WMH volume or distribution were observed between Aβ+ and Aβ- groups.
• Higher axial diffusivity (DA), radial diffusivity (DR), and mean diffusivity (MD) were found in WMHs of Aβ+ individuals compared to Aβ-.
• No significant differences in fractional anisotropy (FA) were detected between the groups.

Conclusions:

• Amyloid accumulation is associated with impaired structural integrity within WMHs, potentially involving demyelination and axonal loss.
• These findings suggest that amyloid pathology may exacerbate the effects of ischemia in WMHs, contributing to cognitive decline.