Background: Microbleeds (MBs) are frequently observed in Alzheimer's disease (AD); however, the relevance to AD pathophysiology has not been elucidated.
Objectives: We investigated correlation of MBs, especially cerebral amyloid angiopathy (CAA)-related MBs with cognitive function, gray matter volume, and glucose metabolism in AD.
Methods: We performed magnetic resonance imaging including T2*-weighted imaging sequence for 206 patients with AD. Among them, 158 AD patients with no focal brain lesions except for MBs were investigated with cognitive tests, voxel-based morphometry, and 18F-fluorodeoxyglucose positron emission tomography in a cross-sectional observational study.
Results: Of the 158 patients with no hemorrhagic and/or ischemic stroke lesions except for MBs, 27 patients had MBs, in which 17 patients showed CAA-related MBs that located only in cortex/subcortex (CAA-related MBs), and 10 patients showed CAA-unrelated MBs that located in deep regions regardless of the presence of MBs in cortical/subcortical regions. There were slightly but significant differences in cognitive functions between the patients without MBs, those with CAA-related MBs, and those with CAA-unrelated MBs. MBs were recognized frequently in the occipital lobe in the patients with CAA-related MBs. The patients with CAA-related MBs showed gray matter atrophy in the temporal lobe and cerebellum, and glucose hypometabolism in the temporal lobe compared with those without MBs.
Conclusions: Our results indicate that MBs, particularly CAA-related MBs would cause gray matter atrophy and glucose hypometabolism in AD.
Keywords: 18F-FDG PET; Alzheimer’s disease; brain microbleeds; cerebral amyloid angiopathy; voxel-based morphometry.