A simple blood test to identify people at risk for Alzheimer’s disease may be close at hand, according to researchers at Columbia University Medical Center in New York City.

They found that blood plasma levels of a peptide called Amyloid Beta (AB42) appear to increase before the onset of Alzheimer’s and decrease shortly after a person develops the disease, which may be because AB42 becomes trapped in the brain.

“To date, AB42 levels have measured most reliably in the cerebrospinal fluid, which is more difficult to collect than blood. Blood draws can be done with relative ease and greater frequency than spinal taps, which is typically the way cerebrospinal fluid is collected,” study lead author Nicole Schupf, associate professor of clinical epidemiology, said in a Columbia news release.

The study was published online Sept. 8 in the journal Proceedings of the National Academy of Sciences.

The finding is similar to that seen in heart attack patients, who typically have elevated lipid levels in their bloodstream before a heart attack but lower post-heart attack lipid levels, said study senior author Dr. Richard Mayeux. He is professor of neurology, psychiatry and epidemiology, and co-director of the Taub Institute of Research on Alzheimer’s Disease and the Aging Brain at Columbia University Medical Center.

Currently, Alzheimer’s-related cognitive impairments can be monitored throughout the course of the disease, but there’s no reliable method of tracking the pathologic progression of Alzheimer’s.

The ability to reliably measure AB42 levels in the blood could enable doctors to predict the onset of Alzheimer’s much earlier, which may help in efforts to fight the disease, according to the researchers.

(Source: Columbia University Medical Center, news release, Sept. 8, 2008)