Blood Test Might Spot Alzheimer's Early

18 proteins ID at-risk patients years before clinical diagnosis, scientists say.

By Jeffrey Perkel
HealthDay Reporter
Monday, October 15, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

MONDAY, Oct. 15 (HealthDay News) -- An international team of scientists has developed a blood test that could reveal which patients with mild cognitive impairment will go on to develop Alzheimer's disease.

If replicated and validated -- and assuming the development of effective treatments against Alzheimer's in the future -- such a test could open the door to medicating at-risk patients earlier and slowing or limiting neurological damage, explained Dr. Allan Levey, chair of neurology at Emory University, Atlanta.

"If it can be replicated, then we will find out how important [the study] really is," said Levey, who was not involved in the research.

The findings were published in the Oct. 14 online issue of Nature Medicine.

According to the Alzheimer's Association, Alzheimer's is a progressive, fatal brain disease that affects almost one in eight individuals over the age of 65.

Yet there currently exists no early diagnostic screen for Alzheimer's disease. Diagnosis today is based not on blood chemistry, but on a combination of psychological and imaging tests. Many of those who present with mild cognitive impairment (MCI), will ultimately develop Alzheimer's disease, but others never do.

"Currently, it's very difficult to know who will progress to Alzheimer's and who will progress to other diseases, or which won't progress at all," said Levey. "Ideally, one wants to be able to know at the stage of mild cognitive impairment, or even earlier, if someone is destined to get Alzheimer's disease."

In the new study, a group led by Tony Wyss-Coray, an associate professor of neurology at the Stanford University School of Medicine, analyzed 259 blood samples obtained from individuals with and without Alzheimer's disease. They focused on 120 proteins involved in cellular signaling and communication.

The team identified 18 proteins in particular whose abundance could distinguish those with Alzheimer's disease from those without it, for an overall accuracy of about 90 percent -- that is, it correctly classified individuals who had been clinically diagnosed with Alzheimer's disease 95 percent of the time and classified as negative those without the disease 83 percent of the time.