The test, which works by identifying changes in signalling proteins that are used by the brain to communication to other parts of the body, was found to be able to detect the disease with 90 per cent accuracy.
Currently, a clinical diagnosis of Alzheimer’s is made by testing for memory loss and cognitive decline.
But the US research team believe that the blood test could soon be used to detect the disease.
The concept of the blood test began after the researchers compared blood samples from five people diagnosed with Alzheimer’s with five people who did not have the disease.
They found a number of changes to a set of signalling proteins found in the blood plasma of the Alzheimer’s patients, which they used as markers for the alterations to the chemistry of the brain that precede Alzheimer’s.
The researchers then decided to expand the study and obtained 259 archived blood samples from individuals who had symptoms of Alzheimer’s.
They developed an analysis procedure to identify if there was a pattern seen in the proteins found in Alzheimer’s patients that could be compared with that of people without the disease.
Eighteen proteins were identified that were specific to Alzheimer’s.
To test out the accuracy of the blood test, the researchers selected 47 people with mild cognitive impairment who had been followed for two to six years.
The blood test was performed on blood samples taken at the beginning of the study.
The test successfully identified 91 per cent of the patients who went on to develop Alzheimer’s by the end of the six-year follow up.
However, the researchers stress that the findings of the blood test still need to be confirmed in other studies.
sanjay.tanday@haymarket.com
Nature Medicine Online 2007
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