Mixed-location cerebral microbleeds as a biomarker of neurodegeneration in a memory clinic population

Area of Science:

• Neurology
• Neuroimaging
• Vascular Neurology

Background:

• Cerebral microbleeds (CMBs) are associated with distinct pathologies based on location: lobar CMBs with cerebral amyloid angiopathy and deep CMBs with hypertensive arteriopathy.
• The neurodegenerative impact of mixed-location CMBs remains largely uncharacterized.

Purpose of the Study:

• To investigate the associations between strictly lobar, strictly deep, and mixed-location CMBs with markers of neurodegeneration, including cerebral atrophy.

Main Methods:

• Recruited 477 memory clinic patients who underwent 3T MRI scans.
• Categorized CMBs into strictly lobar, strictly deep, and mixed-location groups.
• Quantified brain structures (cortical thickness, white matter volume, subcortical volumes) using Free-Surfer and analyzed associations with linear regression models.

Main Results:

• Mixed-location CMBs showed significant associations with reduced limbic cortical thickness (β= -0.01) and smaller accumbens (β= -0.01) and hippocampal presubiculum volumes (β= -0.01).
• Strictly lobar CMBs were associated with reduced total white matter volume (β= -0.03) and region-specific white matter volumes.

Conclusions:

• Mixed-location CMBs are linked to specific patterns of neurodegeneration in limbic and subcortical regions.
• Strictly lobar CMBs are associated with more widespread white matter atrophy.
• Further research is needed to elucidate the underlying mechanisms, potentially involving shared pathways of vascular dysfunction and neurodegeneration.