A blood test may suffice to diagnose Alzheimer's disease 20 years before it occurs. This is demonstrated by a study by the Washington University School of Medicine (WUSTL) in St. Louis. Researchers have developed a test that can identify betamyloid peptides, the proteins that cause the disease's characteristic plaques. This is an even more advanced version of a test developed about two years ago.
The test analyzes the blood samples using a mass spectrometer. In this way it identifies two forms of betamyloid peptide: the betamiloid 42 and the betamiloide 40. When the deposits begin to form in the brain, the relationship between the two decreases. The test is able to identify this change, although there are still no obvious symptoms of what is happening. To test the efficacy of the test, the researchers involved 158 adults at least 50 years old. All participants except 10 had normal cognitive functions. Each patient gave a blood sample and performed a brain CT scan.
The researchers performed the tests and classified the samples based on the results. In 88% of cases, blood tests and CT scans gave identical results. To improve the accuracy of blood tests, scientists combined the results with other risk factors. They therefore took into account age and specific genetic variants.
The operation made it possible to reach an accuracy level of 94%, confirmed by the follow-up carried out in the following years. In some cases the test was even more sensitive than the CT scan. This means that it could identify the disease in its earliest stages, even twenty years before it occurs. In this way it would be possible to slow down the formation of plaques and the progression of the disease.