Researchers at the Washington University School of Medicine, US, and Lund University, Sweden, have separately worked on a blood test that can detect Alzheimer’s disease about 20 years before irreversible symptoms like memory and cognition problems set in.

The test is not yet available to the public, but the researchers say it will be less invasive than a spinal fluid test and less expensive than a PET scan—the two most widely used tests for the diagnosis of Alzheimer's.

PET scan or positron emission tomography is an imaging technique that uses radioactive materials as a dye. One brain scan can cost up to Rs10,000 in India. In the cerebral spinal fluid test, a small amount of fluid is extracted from around the spine to check for the presence of specific chemicals. For the diagnosis of Alzheimer’s, both these techniques look for the build-ups of proteins—beta-amyloids and tau—in the brain.

The new test also looks for tau proteins, specifically p-tau217. But it is said to be so sensitive that it can pick up the presence of p-tau217 protein, linked with Alzheimer’s, from just 4 millilitres of blood. Indeed, the research team at Lund University found that people with Alzheimer’s have seven times the amount of p-tau217 protein in their body compared with people who don’t have Alzheimer’s. 

Alzheimer’s accounts for 60-70% of all dementia cases in the world. That is, 30-35 million people worldwide suffer from this condition that slowly impairs the memory and brain function. Alzheimer’s doesn’t have a cure yet but there is a management protocol to slow down the build-up of protein plaque (beta-amyloid) and protein tangles (tau proteins) in the brain that causes the symptoms of Alzheimer’s.

If rolled out successfully, the new blood test for p-tau217 could solve one of the biggest challenges for medical practitioners working with Alzheimer’s patients today: detecting Alzheimer’s early enough to be able to reverse—or at least arrest—some of its effects.

This test has yet to undergo many rounds of trials before it can be available to the general public. But the researchers are hopeful that it will soon be able to identify people in the early stages of the disease, to participate in drug trials.

  1. Blood plasma test to diagnose Alzheimer’s
  2. Takeaways
Doctors for Early diagnosis of Alzheimer’s may soon be possible, with a simple blood test

This is not the first blood test to help identify Alzheimer’s in a lab setting this year. In March 2020, research at the University of California, San Francisco (partly funded by the US National Institutes of Health’s National Institute on Aging, National Institute of Neurological Disorders and Stroke, and National Center for Advancing Translational Sciences), developed a blood plasma test that looks for another type of tau proteins—p-tau181—using a technology called a single-molecule array or Simoa. Research showed that the test could pick out these proteins from the blood plasma of early-stage patients—some 20 years before the onset of symptoms.

Blood plasma is the liquid that’s left over when you remove red blood cells, white blood cells and platelets from the blood.

In March, too, the researchers were hopeful that this discovery would help them treat these patients and maybe even reverse its effects. They were also hopeful that it would help them recruit younger, healthier patients in drug trials for Alzheimer’s to develop more effective drugs and therapies.

Like the p-tau217 test, the Simoa test for p-tau181 could also differentiate between Alzheimer’s and other types of dementia that affect the frontotemporal region of the brain.

These separate developments are all working towards the same goal: early detection and effective treatment of Alzheimer's.

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Early diagnosis could improve the quality of life of Alzheimer's patients significantly. It could also be the key to ultimately finding a cure for Alzheimer’s. As things stand, there is only a management protocol for the progressive neurodegenerative disease in which memory and other brain functions lapse as protein plaque and tangles accumulate in the brain, killing off brain cells over time.

For some time now, researchers have been trying to devise a blood test to diagnose this disease in the early stages. As new diagnostic technologies become more advanced, the chances of finding biomarkers with greater accuracy and sensitivity increase. Biomarkers are specific chemicals found in the body of patients—for Alzheimer's these biomarkers are beta-amyloid and tau proteins.

The latest Alzheimer’s test, for p-tau217 protein, is a ray of hope for researchers. Perhaps one day in the not-too-distant future, such a test may also be available in every neighbourhood doctors’ clinic.

Dr. Kirti Anurag

Dr. Kirti Anurag

Psychiatry
8 Years of Experience

Dr. Anubhav Bhushan Dua

Dr. Anubhav Bhushan Dua

Psychiatry
13 Years of Experience

Dr. Alloukik Agrawal

Dr. Alloukik Agrawal

Psychiatry
5 Years of Experience

Dr. Sumit Shakya

Dr. Sumit Shakya

Psychiatry
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