Researchers at the Stanford University School of Medicine say that the test spots Alzheimer's by detecting unusual activity in proteins associated with the disease.
The team also claims that the test was determined to be 90 percent correct in diagnosing the problem and 91 percent accurate in predicting who will be afflicted by it.
"Just as a psychiatrist can conclude a lot of things by listening to the words of a patient, so by 'listening' to different proteins we are measuring whether something is going wrong in the cells," Nature quoted Tony Wyss-Coray, PhD, associate professor of neurology and neurological sciences and senior author of the study, as saying.
Seconding the opinion, Lennart Mucke, MD, director and senior investigator of the Gladstone Institute of Neurological Disease at the University of California-San Francisco, said, "I really think it has enormous potential. 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."
Currently, the clinical diagnosis for Alzheimer's is a less-than-perfect process of elimination - by testing for other causes of memory loss and cognitive declines, such as stroke, tumors and alcoholism. If those conditions are eliminated as causes of memory loss, what remains is Alzheimer's, which is the most common cause of dementia. Even the clinical diagnosis is imperfect, and the only definitive diagnosis is by brain autopsy after a person has died.
The researchers measured levels of 120 proteins used by cells to communicate to see if any could give a clue about Alzheimer's.
Samples from five people with Alzheimer's were compared with samples from five people clear of the disease.
The team found that levels of a number of proteins were strikingly different between the two groups.
Next, the researchers further polished their search by examining blood samples from 129 people with symptoms ranging from mild mental impairment to severe Alzheimer's.
They found that Alzheimer's was associated with specific levels of 18 key proteins.
They used this pattern to assess a further 92 patients who had already been clinically assessed for Alzheimer's, and the diagnoses matched in nine out of 10 cases.
The test produced a similar level of success when it was used to examine blood samples which had been taken two to six years earlier from patients, who were then followed up to find out whether their mild mental decline had progressed to something more severe.
"Our hypothesis is that there is something wrong with the production of certain blood cells, which may be needed to clear that stuff that accumulates in the brain in Alzheimer's disease," Wyss-Coray said.
The Stanford team stressed that more work was needed to confirm their results, but Satoris, a company for which Dr Wyss-Coray works as a consultant, plans to develop a prototype test for use in research labs.
The study will appear in the Oct. 15 advance online edition of Nature Medicine.