Early stages of Alzheimer's now detectable

Washington: Researchers have developed a new two-tier method that can detect Alzheimer's disease at an earlier stage. Using the current technique, Alzheimer's disease can only be detected once the typical plaques have formed in the brain of the patients.

The research was published in the journal Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring. "This has paved the way for early-stage therapy approaches," said Klaus Gerwert, lead researchers. In Alzheimer's patients, the amyloid beta protein folds incorrectly due to pathological changes long before the first symptoms occur.

A team of researchers headed by Gerwert successfully diagnosed this misfolding using a simple blood test; as a result, the disease can be detected approximately eight years before the first clinical symptoms occur.

The test wasn't suitable for clinical applications; however, it did detect 71 per cent of Alzheimer's cases in symptomless stages, but at the same time provided false positive diagnoses for nine per cent of the study participants.

In order to increase the number of correctly identified Alzheimer's cases and to reduce the number of false positive diagnoses, the researchers poured a lot of time and effort into optimising the test. As a result, they have now introduced the two-tier diagnostic method. They use the original blood test to identify high-risk individuals.

Subsequently, they add a dementia-specific biomarker, namely tau protein, to run further tests with those test participants whose Alzheimer's diagnosis was positive in the first step. If both biomarkers show a positive result, there is a high likelihood of Alzheimer's disease.

"Through the combination of both analyses, 87 of 100 Alzheimer's patients were correctly identified in our study. And we reduced the number of false positive diagnoses in healthy subjects to 3 of 100. The second analysis is carried out in cerebrospinal fluid that is extracted from the spinal cord," said Gerwert.

"Now, new clinical studies with test participants in very early stages of the disease can be launched," pointed out Gerwert. "Once the typical plaques- amyloid plaques have formed, it seems that the disease can no longer be treated. If our attempts to arrest the progression of Alzheimer's fail, it will put a lot of strain on our society," said Dr Nabers.

The blood test has been upgraded to a fully automated process. "The sensor is easy to use, robust when it comes to fluctuation in concentration of biomarkers, and standardised," explained Andreas Nabers, co-developer of the Alzheimer's sensor.