Identifying Alzheimer’s through a blood test: a revolution, but to what end? : News

Diagnosing Alzheimer’s disease using a simple blood test: This revolution, followed by years of research, is about to become a reality. But for patients, the benefits will only be tangible if effective treatments are finally available.

“Blood biomarkers will change the way we diagnose,” neurologist Giovanni Frisoni, one of the leading European experts in Alzheimer’s disease, summarized to AFP.

For years, it has been one of the main centers of research into this disease, the most common form of dementia, which irreversibly affects millions of people around the world.

The idea is to be able to identify, through a simple blood test, signs that indicate the physiological mechanisms by which the disease sets in.

We know two main mechanisms, without fully understanding their interaction: the formation in the brain of so-called amyloid protein plaques, which compress and eventually destroy neurons; and the accumulation of another protein, called tau, within the neurons themselves.

Examinations already exist: by lumbar puncture or by a medical imaging technique, positron emission tomography (PET). But because they are long, heavy and expensive, many patients are stuck with clinical findings, such as severe memory loss.

Some blood tests are already marketed but, in fact, the remaining data on their actual benefit are little used. However, in recent months, several studies have shown the effectiveness of certain blood tests in identifying internal signs of the disease.

The most notable dates in the JAMA Neurology journal are January. Conducted by following nearly 800 people, it concludes that the blood test makes it possible to identify abnormal amounts of amyloid or tau with comparable effectiveness to tests currently in place.

Crucially, this test is useful at the “preclinical” stage, before the typical symptoms of the disease appear.

The medical world has generally welcomed an important advance despite its limitations. This effectiveness has to be confirmed in actual practice and, above all, such testing only points to the presence of physiological mechanisms that do not systematically result in dementia.

– diagnosis, not screening –

In a response to the British Science Media Center (SMC), neurologist Bart de Strooper concluded that this was “an excellent study that puts us on the verge of being able to use a blood test for Alzheimer’s disease on a daily basis”.

In the UK, this is already almost a reality. A program launched last year by several anti-Alzheimer’s organizations aims to test the benefit of these blood tests within the British healthcare system.

for what Without effective treatment, early diagnosis is of little benefit. However, many neurologists are now hoping that drugs may work.

After decades of unsuccessful research, two treatments — one by the Eli Lilly lab, the other by Biogen — appear to be able to slow the progression of Alzheimer’s by attacking amyloid plaques.

Their effectiveness is modest and side effects are serious, but for many neurologists, they are the first step toward other, more effective treatments.

In this regard, it seems promising to be able to identify Alzheimer’s disease as quickly as possible using a simple blood test to increase the effect of treatment.

There remains a significant nuance. We are talking about an early diagnosis here, in patients already with impaired memory, and certainly not a screening that is aimed at just anyone.

“Today, there is no point in testing blood biomarkers in people who do not have cognitive deficits: it will only do harm,” asserts Mr. Frisoni.

With no concrete means to prevent its appearance, what should we do, in fact, with the announcement that we are at increased risk of developing the disease? Mr. Frisoni, however, does not rule out one day seeing Alzheimer’s testing become a reality.

“We are currently testing some drugs that aim to reduce the risk of Alzheimer’s dementia,” he explains. “Maybe, in five or ten years, it will be in clinical practice. At that point, I will be able to say ‘Yes, I recommend measuring blood biomarkers (as a screening tool).’ But today, no.”

Published at 9:11 am on March 2, AFP

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