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Diagnosing Alzheimer's disease by blood: with an accuracy rate of up to 94%


Scientists have found a way to detect blood in order to accurately identify Alzheimer's disease several years in advance. This has made early intervention possible for people who have Alzheimer's disease but yet haven’t fully realized such a fact.
  • Author Name: Cathy Miller
Editor: Cathy Miller Last Updated: 28-Nov-2019

Previously, early detection of Alzheimer’s disease seems to be very difficult as it takes years for the symptoms to become obvious. Fortunately, scientists have found a way to detect blood in order to accurately identify Alzheimer's disease several years in advance. This has made early intervention possible for people who have Alzheimer's disease but yet haven’t fully realized such a fact.

The struggle against Alzheimer's has been on-going for over one hundred years, but so far we have not found a way to control or reverse cognitive decline and memory loss. Although some drugs can relieve the symptoms of Alzheimer's disease, they cannot completely cure it.

The challenges of treating Alzheimer's disease lies in the fact that Alzheimer's disease is often diagnosed too late. Therefore, only a few measures can be taken then. When Alzheimer's patients develop symptoms of decreased thinking, his brain neurons have been destroyed, which are almost impossible to get repaired.

Therefore, people envisioned: Is it possible to develop a reliable method to find Alzheimer's patients before symptoms like memory regression occur? Scientists at the University of Washington School of Medicine have recently developed a new blood test that is able to detect symptoms of Alzheimer's disease several years before symptoms start to appear. Surprisingly, compared with the PET test, which has long been perceived as the “gold standard”, this blood pressure test is more sensitive and reaches an accuracy rate of 94%. The findings were published in Neurology.

Procedures of the study

The study collected data from 158 adults in their fifties. The researchers used mass spectrometry to accurately measure the amount of amyloid β42 and amyloid β40 in the blood of the sample. Mass spectrometry techniques yield a mass spectrum of a particular ion characteristic of a protein by evaporating the compound in the blood sample and then ejecting it with an electron beam.

Although everyone has amyloid, in some cases, abnormal aggregation of proteins can form plaques in the brain. These plaques are viewed as important biomarkers in the diagnosis of Alzheimer's as they would cause the death of nerves, and thus cut off nerve transmission signals.

Two major tests - blood tests and PET scans – were performed on volunteers. The results show that the probability of blood test results consistent with PET scan results was only 88%. To provide greater accuracy for clinical diagnosis, the researchers decided to factor other major risk factors that are also likely to cause Alzheimer's disease, such as age, gender and genetic variation. After the researchers incorporated the above-mentioned risk factors into the analysis, they found that the accuracy rate could be raised to 94%.

Blood testing: accurate and cost-effective

In a four-year study, some volunteers' blood tests were found to have produced false positives.  What does “false positive” mean? To put it simply, the results of blood test (positive) is different from that of the initial PET test (negative), and the subsequent brain scans prove it is positive, matter-of-factly. This finding powerfully presents us a fact that blood tests may be more accurate than the so-called "gold standard" PET test.

In the past, the only way for people to scan for Alzheimer's disease is through brain scans, which takes years of testing and is quite expensive. But through blood tests, we can do it every month. Screening thousands of people means more effective participation in clinical testing, which helps medical workers find treatments faster and lessen the suffering of patients and their families.

From the perspective of research cost, pre-screening by blood test and PET scan confirmation can reduce the number of PET detection by two-thirds. And each PET scan can cost as much as $4,000. With the money and time saved, we can conduct two clinical trials.


It is worth noting that this blood test for Alzheimer's disease still has shortcomings. One of the questions is how clinicians set thresholds for "normal" and "high" levels of amyloid or other proteins in the blood. Furthermore, it is not 100% for sure thatβ-amyloid fragments will certainly lead to the occurring of Alzheimer's disease, based on the fact that not all people carrying amyloid plaques will develop into this disease in the end. But anyway, the discovery of a reliable way to predict changes in amyloid levels will be a new starting point for treating Alzheimer's patients. We have reason to believe that one day in the future we will eventually defeat Alzheimer's disease.

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