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Researchers have found a way to predict the development of Alzheimer's disease years before its onset. The study was supported by the John Douglas French Alzheimer's Foundation, the Alzheimer's Association, the U.S. National Institute on Aging and Satoris, Inc. Dr. Wyss-Coray is a co-founder of Satoris, and two of his co-authors are employees of the company.

A group of proteins in blood plasma, involved in inflammatory and immune processes, appears to distinguish Alzheimer's from controls with close to 90 percent accuracy, and could one day offer a predictive diagnostic test, according to its developers. Currently there no definitive biological test for diagnosing or ruling out the presence of Alzheimer's disease or predicting its onset.

The experimental protein panel, if verified in additional tests, could also predict which patients with mild cognitive impairment may progress to Alzheimer's-type dementia within six years, reported Tony Wyss-Coray, Ph.D., of Stanford, and colleagues.

The authors, speculating that it might be possible to screen for the early signs of Alzheimer's disease by looking for changes in the concentrations of cell signaling proteins, collected 259 stored plasma samples from patients who later went on to develop Alzheimer's disease, as well as those with mild cognitive impairment, late-stage Alzheimer's, and non-demented controls. They measured levels of 120 known signaling proteins, and then used the data to develop training sets of microarrays for predictive analysis, which eventually yielded a panel of 18 proteins.

Researchers set about to see whether the predictive protein microarrays could distinguish between molecular Alzheimer's or non-Alzheimer's. The samples included plasma from patients with Alzheimer's disease and other types of dementia, and from non-demented controls.

They found that predictive analysis of microarrays correctly classified samples as Alzheimer's disease with 90 percent accuracy, and ruled out Alzheimer's correctly in 88 percent of samples.

"I really think it has enormous potential," said Lennart Mucke, M.D., director and senior investigator of the Gladstone Institute of Neurological Disease at the University of California San Francisco, who was not involved in the study. "Most researchers in this field agree that there is an urgent need for better lab tests for Alzheimer's disease, and this study has addressed this need admirably."