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Will we soon be able to diagnose Alzheimer’s disease well before symptoms appear? In any case, this is what a new study on a brand new blood test concludes.
Alzheimer’s disease is a neurodegenerative pathology whose diagnosis is made when the first symptoms appear. To improve the detection of this pathology, researchers have developed a new blood test.
A biomarker targeted by a blood test
For this work, the scientists were interested in a cohort of 786 people whose average age was 66 years. Some showed signs of dementia but others did not. The researchers collected data from these volunteers, taken from brain scans and blood samples.
They were thus able to demonstrate that the presence of a biomarker in the blood, a phosphorylated tau protein called p-tau217, was linked to Alzheimer’s disease. This biological element could be an early marker of the disease, because its quantity increases over time, along with the disease-causing beta-amyloid and Tau proteins.
“A robust and accurate blood-based biomarker would enable more comprehensive assessment of cognitive impairment in settings where advanced testing is limited.” the scientists congratulate themselves.
More than 90% reliable results
According to the results of this study, this new blood test has an accuracy of 97% for tau protein. According to Nicholas Ashton, professor of neurochemistry at the University of Gothenburg in Sweden and one of the main authors of the study, whose comments are reported by our colleagues at CNN, “What was impressive about these results was that the blood test was just as accurate as advanced tests like spinal fluid tests and brain scans in showing Alzheimer’s disease pathology in the brain”.
Indeed, among the 786 volunteers tested, only 20% of patients required additional examinations. “80% of individuals could be definitively diagnosed through a blood test without any further investigation” believes Nicholas Ashton.
A possibility of detecting the disease more than 15 years before symptoms
The main limitation of this test is highlighted by the researchers. They recall the specificity of the tau protein to Alzheimer’s disease. This means that if the test is carried out on a demented person, it can simply rule out this diagnosis, without detecting the real cause of the dementia. The other limitation could be its cost, estimated between 200 and 500 dollars.
On the other hand, the benefit of this test, which is easy to perform, will make it possible to detect the presence of the disease many years before the appearance of symptoms. Indeed, early signs of Alzheimer’s disease can be detected between 15 and 20 years before symptoms appear. Recall that currently, to identify the accumulation of beta-amyloid and tau proteins in the brain, patients must undergo brain scintigraphy or a lumbar puncture, invasive, inaccessible and expensive examinations.
Another blood test already available on the market
This is not the first time that scientists have attempted to develop this type of test. Last year, the first blood test to detect beta-amyloid protein, called AD-detecter, was made available to consumers in the United States.
According to the company that markets it, this test is simply intended to assess the risk of developing the disease for an individual and not to diagnose the disease. Hence the importance of developing a reliable test. It is estimated that 225,000 people are diagnosed with the disease each year in France.