Preliminary findings from a study by National Institute on Aging (NIA) scientists and colleagues showed that a blood test for Alzheimer’s-related proteins may accurately predict who might be at risk for the disease years before symptoms develop. The test measured the levels of several tau and amyloid proteins—the hallmarks of Alzheimer’s disease—in exosomes, microscopic organelles shed by brain cells.

The study by Dimitrios Kapogiannis, Ph.D., and Edward Goetzl, M.D., both of the NIA Intramural Research Program, Baltimore, and researchers at the Mayo Clinic, Rochester, Minn.; University of Kentucky, Lexington; Georgetown University, Washington, D.C.; University of California, San Francisco; and the University of Rochester, N.Y., appeared online in the August 15, 2014 issue of Alzheimer’s & Dementia. The work was funded by NIA, the University of Kentucky, Lexington, and Nanosomix, Inc.

Compared to those free of the disorder, the blood test showed people with Alzheimer’s had higher elevations of three proteins (p-5396-tau, p-181 tau, and Ab42) in exosomes. The test was 96 percent accurate in distinguishing between these two groups. Significantly, the investigators also found elevated levels of these proteins in blood samples collected from cognitively healthy older people who later developed dementia within one to ten years.

While this case-controlled study needs to be replicated, it offers intriguing insights into novel ways to detect Alzheimer’s disease at its earliest stages. The work was funded by NIA, the University of Kentucky, Lexington, and Nanosomix, Inc.

Reference: Fiandaca MS, et al. Identification of pre-clinical Alzheimer’s disease by a profile of pathogenic proteins in neurally-derived blood exosomes: a case-control study. Alzheimer’s & Dementia.