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2012 Grants - Carmichael
Imaging Biomarkers of Preclinical Cerebrovascular Disease
Owen T. Carmichael, Ph.D.
University of California, Davis
2012 New Investigator Research Grant
Alzheimer's disease appears to have an extensive "preclinical phase," or a stage that occurs before significant cognitive decline or other clinical symptoms arise. This phase is often characterized by the accumulation of protein biomarkers in the brain, including the protein fragment beta-amyloid and an abnormal form of tau protein. However, increasing evidence suggests that blood flow problems in the brain may also play a role in preclinical Alzheimer's. Such abnormal blood flow is often labeled as preclinical cerebrovascular disease (CVD). Yet scientists have not determined exactly how CVD influences the progression of early Alzheimer's, largely because CVD biomarkers have not been precisely determined.
Owen T. Carmichael, Ph.D., and colleagues plan to use sophisticated magnetic resonance imaging (MRI) techniques to assess four potential biomarkers of preclinical CVD: reduced brain blood flow; tiny hemorrhages (areas of bleeding) in the brain; small, stroke-related lesions; and the narrowing of carotid arteries that lead to the brain. For this effort, the researchers will enlist a diverse group of 50 cognitively-healthy, elderly participants from a large Alzheimer's study at the University of California, Davis. Aside from receiving MRI scans, the participants will undergo positron emission tomography (PET) imaging to assess their levels of brain beta-amyloid. Dr. Carmichael's team will then quantify the relationships between the four potential CVD biomarkers and the participants' cardiovascular risk factors, the health of their brains' gray and white matter, and their cognitive abilities. Results of this effort could lead to larger studies that clarify, step-by-step, how CVD-related brain changes occur over time. Ultimately, such work could identify treatments that target both cerebrovascular disease and dementia.