Cerebral Blood Flow Reduction from Microbleeds Causes Cognitive Deficits

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A reduction in cerebral blood flow (CBF), associated with cerebral microbleeds, may raise the risk of neuronal injury and neurodegeneration in elderly people.

Cerebral microbleeds (CMBs) are a common MRI finding in elderly patients, and are associated with cognitive deficits. However, prior to this study, incidental CMBs in cognitively healthy people have not been reported in association with abnormalities in CBF. Nicholas M. Gregg, MD, of the University of Pittsburgh, and colleagues sought to analyze the association between incidental CMBs and resting-state CBF, cerebral metabolism, cerebrovascular disease, beta-amyloid, and cognition.

Using 3-Tesla MRI and positron emission tomography, the researchers conducted a cross-sectional study on 55 cognitively normal individuals (mean age 86.8 years) from May, 2010 to May, 2013.

They found that the presence of cortical CMBs was linked to a significant reductions in CBF across multiple brain regions (percentage difference in global CBF, −25.3%; P = .0003), with the largest seen in the parietal cortex (−37.6%; P < .0001) and precuneus (−31.8%; P = .0006). People with CBF showed a trend towards reduced CBF, but this was not significant. Those with cortical CMBs showed a significant association with a higher prevalence of infarcts (24% vs 6%; P = .047) and greater cognitive deficits as determined by the Clinical Dementia Rating scale (45% vs 19%; P = .12). There was no difference in cortical amyloid observed between participants with or without CMBs.

The researchers concluded that chronic hypoperfusion may increase risk of neuronal injury and neurodegeneration, and suggested that resting-state CBF may be a biomarker of CMB-related small vessel disease.

Brain blood vessels
Cerebral Blood Flow Reduction from Microbleeds Causes Cognitive Deficits

Cerebral microbleeds (CMBs) are collections of blood breakdown products that are a common incidental finding in magnetic resonance imaging of elderly individuals. Cerebral microbleeds are associated with cognitive deficits, but the mechanism is unclear. Studies show that individuals with CMBs related to symptomatic cerebral amyloid angiopathy have abnormal vascular reactivity and cerebral blood flow (CBF), but, to our knowledge, abnormalities in cerebral blood flow have not been reported for healthy individuals with incidental CMBs.

Researchers evaluated the association of incidental CMBs with resting-state CBF, cerebral metabolism, cerebrovascular disease, β-amyloid (Aβ), and cognition.

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