Mayo Researchers Identify a Good Predictor for Those at Greater Risk of Alzheimer's Disease
By looking at the ratio between two forms of amyloid beta (AЯ) protein, researchers at Mayo Clinic believe they have found a way to identify which normal, elderly people might develop Alzheimer's disease (AD) and its precursor, mild cognitive impairment (MCI).
Mayo Clinic scientist Dr. Steven Younkin was among the first to discover that AЯ is a secreted protein normally present in blood and spinal fluid. Most AЯ is in a form made up of 40 amino acids (AЯ40), but a small percentage has 42 amino acids (AЯ42). In all people with Alzheimer's, AЯ42 deposits in the brain to form senile plaques, which are one of the pathological hallmarks of the disease. Studies conducted at Mayo Clinic on mice genetically engineered to develop AD show that AЯ42 declines in both the blood and spinal fluid as it begins to deposit in the brain.
Younkin and Mayo Clinic neurologist Dr. Neill Graff-Radford led a team of researchers who analyzed AЯ to determine if it is useful for identifying elderly individuals most at risk for developing Alzheimer's disease. "There is a growing consensus that the best way to manage Alzheimer's disease will be through preventive therapy," says Graff-Radford. "To develop and administer preventive therapy, it is essential to develop biomarkers that can be used to identify at-risk individuals in the same way that cholesterol levels are used to identify those at risk for heart disease."
Specifically, the Mayo team looked at the ratio of AЯ42 to AЯ40 in blood. They took samples from 563 normal volunteers and followed them for two to 12 years. Researchers found that subjects with the lowest ratio of AЯ42 to AЯ40 were at the greatest risk of getting