Simple Blood Test May Identify People At Risk Of Developing Alzheimer’s Disease

A 20-year study by researchers at Columbia University Medical Center has found that a simple blood test may identify people at risk of developing Alzheimer’s Disease. These ground-breaking findings could change the way the disease is treated or someday prevent it.

The findings indicate that people with elevated levels of a certain peptide in the blood plasma, Amyloid Beta 42 (Aß42), are at increased risk of developing Alzheimer’s disease. Conversely, a decline of Aß42 in the bloodstream may signal the compartmentalization or “traffic jam” of Aß42 in the brain, which occurs in the brains of people with Alzheimer’s.

“To date, Aß42 levels have measured most reliably in the cerebrospinal fluid, which is more difficult to collect than blood,” said Nicole Schupf, Ph.D., Dr.P.H., associate professor of clinical epidemiology at Columbia University Medical Center and lead author of the paper. “Blood draws can be done with relative ease and greater frequency than spinal taps, which is typically the way cerebrospinal fluid is collected.”

The study showed researchers that plasma levels of Aß42 appear to increase before the onset of Alzheimer’s disease and decline shortly after the onset of dementia. They deduce that Aß42 trapped in the brain could account for the decrease in levels post-dementia. Richard Mayeux, M.D., M.S., professor of neurology, psychiatry, and epidemiology, and co-director of the Taub Institute of Research on Alzheimer’s Disease and the Aging Brain at CUMC, led the Northern Manhattan study, and compares findings finding to something similar seen in heart attack patients, who typically have elevated lipid levels in their bloodstream prior to a heart attack, but decreased post-heart attack lipid levels.

Dr. Mayeux, the senior author of this paper, reported that, using more specific antibodies developed by the Ravetch Laboratory at Rockefeller University, the research team isolated the most harmful form of amyloid compound, the protofibrillar form of Aß. While the cognitive impairments of Alzheimer’s can be monitored throughout the disease course, clinicians have had no reliable way to monitor the pathologic progression of the disease.

Being able to reliably measure Aß levels in the blood could provide clinicians with a tool that forecasts the onset of Alzheimer’s much earlier. Earlier detection would of course be an important step in combating the disease, researchers said.

Source: Proceedings of the National Academy of Sciences, Sept. 8, 2008

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