Dementia Earlier and easier Alzheimer's diagnosis with new blood test

Diagnosis Dementia: blood test for Alzheimer's in prospect

According to health experts, it is possible to prevent Alzheimer's disease through certain measures, but unfortunately the neurodegenerative disease is not curable. However, if diagnosed early, it may be stopped. Researchers have now been able to develop a new blood test that could enable earlier diagnosis of Alzheimer's.

Early diagnosis important

As with many other diseases, it is important in Alzheimer's disease to diagnose the disease as early as possible. Although the disease can not be cured at this time, there are indications that a delay in the course of the disease can be achieved if diagnosed early. Helpful here could be a new blood test.

Researchers have developed a new method that could serve for the early detection of Alzheimer's disease. A first blood test for dementia diagnosis seems in sight. (Image: Dan Race / fotolia.com)

Blood test for the early detection of Alzheimer's

Over the last few years, new blood tests for early detection of Alzheimer's have been reported time and again.

For example, one US researcher found in an investigation 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 in 90 percent of cases for early detection of the disease.

The German Society for Neurology (DGN) also reports in a communication about the blood test, which has proved so promising.

Earlier and easier diagnosis of the disease

According to 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 were from healthy people, from those with mild cognitive disorders (MCI) or from Alzheimer's patients, the scientists report in the journal Nature..

"This could allow earlier and easier diagnosis of Alzheimer's disease," said Professor Richard Dodel, dementia expert at DGN.

As the DGN writes, there is currently no drug that stops the onset or progression of Alzheimer's disease. Patients therefore have no direct benefit from the test, emphasizes the neuro-geriatrist.

High precision

The test accurately determines β-amyloid (Aβ), a protein fragment that can accumulate in the brains of Alzheimer's disease decades before the onset of clinical symptoms.

So far, it can only be reliably proven with two methods: recording of the brain with a special variant of positron emission tomography ("amyloid PET") or removal of nerve water as part of a lumbar puncture with subsequent detection of various proteins (Aβ and tau protein).

"The first method requires a high expenditure on equipment and logistics with corresponding costs, the second method may be a burden especially for older patients," said Neurogeriater Richard Dodel, chair holder at the University Hospital Essen and chief physician of the geriatric center Haus Berge at the Elisabeth Hospital. "Much better would be a blood test."

Only in very low concentrations in the blood

Aβ is found in the blood but only in very low concentrations. Attempts to detect it using immunoassays (ELISA) and to deduce their concentrations in the brain 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.

Also, they did not determine the total amount of Aβ but the concentration ratio of three Aβ variants to each other: Aβ42, Aβ40 and APP669-711.

The reliability of the method was tested on the basis of 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 Aβ deposits in the brain or not. With the combination of two quotients for the different Aß variants, the prediction accuracy reached 90 percent.

Application in clinical trials

The first applications of the neurologist Dodel expected in clinical trials.

"A reliable blood test would be a step forward in the research of therapies that target early stages of Alzheimer's disease, with the goal of slowing or even stopping their progression," explains the expert.

"Study participants with high levels of Aβ would be easier to identify, and it may be easier than previously to determine the impact of drug candidates on the deposits."

In the medium term, a blood test can also improve the diagnosis in case of suspicion or help identify people with high levels of stress, Dodel continued. "Before admission, however, the results have to be confirmed independently - and the question of costs must also be clarified." (Ad)