Japanese researchers have approved a new blood test to detect Alzheimer's. A laboratory study reveals an increased content of amyloid in the brain with an accuracy of 90%. The first blood test in the near future will be used in ordinary municipal hospitals.
Amyloid fragments determined by mass spectroscopy
Positron emission tomography (PET) has so far been used to diagnose Alzheimer's disease. If a certain amount of amyloid “caught fire” in PET, this indicated a pathology. Together with the clinical symptoms, PET was used to accurately diagnose Alzheimer's disease.
Amyloid PET, however, is an expensive study and therefore unsuitable for widespread use..
An analysis of cerebrospinal fluid also gives useful results, but there is nothing simpler than a blood test.
Over the past 3 years, scientists have conducted dozens of studies that have proven the high accuracy of the study. The introduction of the method into clinical practice is planned closer to 2020, when the last major trials are over. The cost of a new blood test, researchers promise, will be 8-10 times lower than PET and cerebrospinal fluid analysis.
Are further blood tests necessary?
The Australian-Japanese research team used antibodies to specific amyloid beta fragments in their analysis.
The procedure, called mass spectroscopy, was previously evaluated in small studies.
Conventional laboratory diagnostic tests for amyloid beta fragments have always been unsuitable for serum analysis. However, the mass spectroscopic method is much more accurate, especially when combining the values of several amyloid fragments.
Researchers in Japan have focused on the amyloid precursor protein fragment designated APP669-711. Two amyloid beta fragments — Aβ1-40 and Aβ1-42, were also analyzed.
The latter are also analyzed in cerebrospinal fluid in cases of suspected Alzheimer's disease. In the disease, Aß1-42 protein predominates. Thus, the detection of these factors can prove amyloid pathology.
97% sensitivity to Alzheimer's
Researchers first tested and optimized the analysis on study participants in Japan. All trials included elderly people with cognitive deficits and patients with confirmed Alzheimer's dementia.
All participants were regularly examined with amyloid PET, so the entire course of dementia was recorded from the preclinical phase.
By analyzing participants' serum using mass spectroscopy, the researchers found very significant differences between patients with high and low levels of amyloid in the brain.
The differences were most pronounced when they combined the meanings of the two studies. In the Australian group, elevated levels of amyloid in the brain were measured with a diagnostic accuracy of 90%.
Diagnostic accuracy in similar studies reached 92%.
Comparable to cerebrospinal fluid analyzes
Some of the study participants also provided cerebrospinal fluid samples. Scientists have found the same correlation of blood test results with PET data and with CSF biomarkers.
If the analysis is successful in further studies, many studies (PET or CSF analysis) in patients with an unclear diagnosis may become unnecessary.
It is also interesting to note that Alzheimer's disease can be proven or ruled out with very high accuracy in healthy people.
In a Japanese study, 9 out of 31 patients with clinical Alzheimer's disease did not have elevated levels of amyloid in PET. They did not, by definition, have Alzheimer's disease. However, a new blood test helped to identify pathology in the asymptomatic and initial phase.
Researchers tested 31 more patients with clinical Alzheimer's disease and 20 healthy elderly volunteers. They concluded that their results are reliable and reproducible.
