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Dementia diagnosis: prospect of Alzheimer's blood test
According to health experts, it is possible to prevent Alzheimer's by taking certain measures, but unfortunately the neurodegenerative disease is not curable. However, if she is diagnosed early, she may be stopped. Researchers have now succeeded in developing a new blood test that could enable an earlier diagnosis of Alzheimer's.
Early diagnosis is important
As with many other diseases, it is important in Alzheimer's to diagnose the disease as early as possible. Although the disease cannot yet be cured at the moment, there are indications that a delay in the course of the disease can be achieved with an early diagnosis. A new blood test could be helpful here.
Blood test for early detection of Alzheimer's
In recent years there have been repeated reports of new blood tests for early detection of Alzheimer's.
For example, US researchers found in a study that such a test can detect the disease years before the onset of the disease.
And Japanese and Australian scientists recently published study results that showed that their newly developed blood test was used to diagnose the disease 90 percent of the time.
The German Society for Neurology (DGN) is now reporting in a message about the blood test, which has proven to be so promising.
Earlier and easier diagnosis of the disease
According to the DGN, the researchers have succeeded in determining peptides in the blood that are characteristic of Alzheimer's disease.
From the concentration ratios, they can also read with high accuracy whether the blood samples came from healthy people, those with mild cognitive disorders (MCI) or from Alzheimer's patients, the scientists report in the journal "Nature".
"This could enable an earlier and easier diagnosis of Alzheimer's disease," said Professor Richard Dodel, DGN dementia expert.
As the DGN writes, there is currently no drug that can stop the onset or progression of Alzheimer's disease. Therefore, the neurogeriatrist emphasizes that patients still have no immediate benefit from the test.
The test determines with great accuracy β-amyloid (Aβ), a protein fragment that can accumulate in the brain of Alzheimer's patients decades before the clinical symptoms break out.
So far, it can only be reliably demonstrated using two methods: by imaging the brain with a special variant of positron emission tomography ("amyloid PET") or by removing nerve water in the context of a lumbar puncture with subsequent detection of various proteins (Aβ and tau protein).
"The first method requires a high level of equipment and logistics with corresponding costs, the second method can be a burden, especially for older patients," said neurogeriatrist Richard Dodel, chair holder at the Essen University Hospital and chief physician of the Haus Berge geriatric center at the Elisabeth Hospital. "A blood test would be much better."
Only in very low concentrations in the blood
Aβ is only found in the blood in very low concentrations. Attempts to detect it there with the help of immunoassays (ELISA) and to deduce the concentrations in the brain from them had led to inconsistent results in the past.
In the new work, the Japanese and Australian researchers used a combination of immunoprecipitation and mass spectroscopy that is much more sensitive than ELISA.
They also did not determine the total amount of Aβ, but the concentration ratio of three Aβ variants to one another: Aβ42, Aβ40 and APP669-711.
The reliability of the method was tested using two groups of a total of 373 patients who had already been examined with PET and other methods in Japan and Australia.
The new test was able to predict with high reliability whether the study participants had Aß deposits in the brain or not. With the combination of two quotients for the different Aß variants, the prediction accuracy reached 90 percent.
Use in clinical studies
The neurologist Dodel expects the first applications in clinical studies.
"A reliable blood test would be a step forward in the research of therapies that start in early phases of Alzheimer's disease with the aim of slowing the course or even stopping its progression," explains the expert.
"Study participants with a high Aβ load would be easier to identify, and it could be easier than ever to determine the influence of drug candidates on the deposits."
In the medium term, a blood test can also improve diagnosis in the event of a suspected case or help to identify people with high levels of stress, Dodel continues. "Before admission, however, the results must be confirmed independently - and the cost issue also needs to be clarified." (Ad)