Blood Test Predicts Alzheimer's Decades Before Symptoms Appear

The orange patches represent beta-amyloid plaques associated with Alzheimer's disease. Juan Gaertner

A blood test for the beta-amyloid plaques associated with Alzheimer's disease appears to provide a reliable way to assess a person's chances of getting the disease long before symptoms appear. Currently, there is little someone with an Alzhiemer's diagnosis can do. However, if any of the Alzheimer's treatments currently under trial succeed, the blood test could become an essential component in turning the tide on the most common cause of dementia.

In the 80s, the Florey Institute's Professor Colin Masters co-led the team that purified and sequenced the beta-amyloid plaques found in the brains of people with Alzheimer's disease. Although this was an essential step for understanding the disease and working towards a cure, it did nothing at the time for diagnosis. The plaques could only be found by dissecting the brain, which people don't take well to when alive.

More recently, positron emission tomography scans have made detection possible, but the cost is too high for widespread use. Cerebral spinal fluids can reveal the presence of beta-amyloid above normal levels, but collecting this is invasive and often unpleasant. Consequently, teams worldwide have been in a race to develop a cheap and non-invasive test.

Now, Masters is part of a team that describe in Nature the use of mass spectrometry to measure even very low concentrations of beta-amyloid in the blood. The authors include Dr Koichi Tanaka, who shared the 2002 Nobel Prize for the use of mass spectrometry to analyze large biological molecules.

In trials conducted in Australia and Japan, the test revealed the presence of abnormally high beta-amyloid levels in the blood of people diagnosed with Alzheimer's, as well as in people who are cognitively normal but whose plaques have been revealed by other methods.

Masters told IFLScience: “It depends on age and genetics as to when these people will begin to show cognitive decline, but if they live long enough they will develop impairment.”

With the process of Alzheimer's evolution taking an average of around 30 years, much of which is symptom free, the test could offer plenty of warning. Masters added that environmental factors such as exercise, sleep, education, and diet appear to be able to delay the effects, but appear to do so to only a small degree, unlike for other forms of dementia.

This may make getting tested appear pointless, but Masters noted that at least one medication looks promising where symptoms are already visible, and early application might be even better.

Medical tests can be brought to market much more quickly than therapies that need to undergo long clinical trails, and IP for the trial already rests with the Shimadzu Corporation who are likely to make it available quickly.

The new test has major advantages over existing methods. Japanese National Center for Geriatrics and Gerontology

 

 

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