Coming soon! Simple blood test for accurate diagnosis of Alzheimer's

The researchers have devised a cost-effective blood test that can help in the accurate diagnosis of Alzheimer's disease (AD) even before the obvious symptoms set in, according to a new study published in the journal Alzheimer's & Dementia.

The new blood test is significant as the diagnosis of the Alzheimer's disease is usually hard before the appearance of symptoms. And also, may currently available tests are complicated and expensive.

The tau protein plays an important part in the development of AD, and there is an increasing interest in measuring tau in cerebrospinal fluid (CSF) and blood.

Dominic M. Walsh, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA, and colleagues developed a set of immunoassays to measure tau in specimens from humans diagnosed based on current best clinical and CSF biomarker criteria.

Millions of people are affected by AD worldwide, despite this, there are only a few means of its accurate diagnosis. These include CT and MRI scans, which help doctors rule out other conditions that might cause similar symptoms.

Another way of diagnosing Alzheimer's is by collecting cerebrospinal fluid and looking for biomarkers of the disease. This is the most accurate test for this neurodegenerative condition, but it is costly and invasive.

For all these reasons, Dominic M. Walsh, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA, and colleagues have been developing a blood test for Alzheimer's that aims to be accurate, more cost-effective, and less unpleasant.

Tau proteins play an important part in the development of the disease. Build up of the protein in brain results in the formation of toxic plaques, a biomarker for Alzheimer's and other types of dementia.

Tau proteins are made of related molecules with somewhat different properties. In the new study, the researchers started by devising a method to identify the specific subset of tau molecules that appear at high levels in Alzheimer's disease.

The researchers came up with ways of detecting different types of tau molecules in both blood and cerebrospinal fluid, and they tested these methods in samples of plasma (a blood component) and cerebrospinal fluid from two sets of participants (65 in the first group and 86 in the other).

One group of samples came from volunteers enrolled in the Harvard Aging Brain Study and some who had participated in research at the Institute of Neurology in London, United Kingdom.

The second group came from volunteers recruited by specialists at the Shiley-Marcos Alzheimer's Disease Research Center at the University of California, San Diego.

The team assessed five tests for tau molecules, looking to see which would be most effective. In the end, the scientists settled on a test that they called "the NT1 assay," which demonstrated both sensitivity and specificity, meaning that it was able to accurately detect Alzheimer's.

"A blood test for Alzheimer's disease could be administered easily and repeatedly, with patients going to their primary care office rather than having to go into [the] hospital," claims study author Dominic Walsh.

"Ultimately, a blood-based test could replace cerebrospinal fluid testing and/or brain imaging," he suggests, adding, "Our new test has the potential to do just that."

"Our test will need further validation in many more people, but if it performs as in the initial two cohorts, it would be a transformative breakthrough."

"Further trials are needed with a larger group of participants to establish the effectiveness of the tests, in spite of the tests being verified in blood samples from two different cohorts," write the authors.

For further reference follow the link: https://doi.org/10.1016/j.jalz.2018.09.010