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Cerebral Microbleeds Are Associated with Cerebral Hypoperfusion in Patients with Alzheimer's Disease
Yutaka Hatada1, Mamoru Hashimoto2, Shinya Shiraishi3
1Department of Psychiatry, Heisei Hospital, Yatsushiro, Kumamoto, Japan.
Background:
Although cerebral microbleeds (CMBs) are commonly observed in patients with Alzheimer's disease (AD), their clinical relevance for AD remains unclear.
Objective:
We investigated the significance of CMBs in AD by examining the relationship between CMBs and cerebral blood flow (CBF) in patients with AD.
Methods:
Thirty-four patients (aged 77.9±7.6 years; 17 men) with probable AD and multiple (≥8) CMBs were selected from 394 consecutive patients. For each lobe of the brain, the correlation between the number of CMBs observed on susceptibility-weighted images and the decrease in CBF observed on single-photon emission computed tomography was assessed.
Results:
The number of microbleeds was significantly correlated with the severity of decrease in the occipital lobe (Spearman's r = 0.531, p < 0.001) and temporal lobe (r = 0.437, p < 0.001) but not in the frontal lobe (r = 0.201, p = 0.101) and parietal lobe (r = 0.178, p = 0.146). These results were unchanged in the partial correlational analysis after controlling the effect of other small vessel disease such as lacunars and white matter hyperintensities.
Conclusion:
Multiple CMBs are associated with cerebral hypoperfusion in AD. The effects of CMBs on CBF differed according to brain location, possibly reflecting different distributions of the underlying cerebral amyloid angiopathy and AD-related histopathology, such as neurofibrillary tangles.
Insights
Multiple cerebral microbleeds (CMBs) in Alzheimer's disease (AD) patients are linked to reduced cerebral blood flow (CBF), particularly in the occipital and temporal lobes. This association highlights CMBs as a significant factor in AD-related hypoperfusion.
Area of Science:
- Neurology
- Neuroimaging
- Geriatrics
Background:
- Cerebral microbleeds (CMBs) are frequently observed in Alzheimer's disease (AD) patients.
- The precise clinical significance of CMBs in the context of AD pathogenesis remains incompletely understood.
Purpose of the Study:
- To investigate the relationship between the presence of CMBs and cerebral blood flow (CBF) in individuals diagnosed with probable AD.
- To determine if CMBs contribute to reduced CBF in AD patients.
Main Methods:
- Thirty-four probable AD patients with multiple (≥8) CMBs were selected.
- Susceptibility-weighted imaging (SWI) was used to identify and quantify CMBs.
- Single-photon emission computed tomography (SPECT) was employed to assess CBF across different brain lobes.
- Correlation analyses were performed to evaluate the association between CMB counts and CBF in each lobe, controlling for other small vessel disease markers.
Main Results:
- A significant negative correlation was found between the number of CMBs and CBF in the occipital lobe (Spearman's r = 0.531, p < 0.001) and temporal lobe (r = 0.437, p < 0.001).
- No significant correlation was observed between CMBs and CBF in the frontal or parietal lobes.
- These findings persisted after adjusting for confounding factors like lacunar infarcts and white matter hyperintensities.
Conclusions:
- Multiple CMBs are associated with reduced cerebral blood flow (cerebral hypoperfusion) in Alzheimer's disease.
- The impact of CMBs on CBF varies by brain region, potentially reflecting regional differences in cerebral amyloid angiopathy and AD-related neuropathology.