Scientists Refine Alzheimer's Simple Blood Test

Texas researchers have created a new blood test that could detect Alzheimer’s disease, facilitating earlier detection and treatment of this disease affecting millions of people worldwide. A report cross-validating the test has been published in the December issue of the international scientific journal PLoS ONE, which also was presented at the Alzheimer’s Association International Conference on Alzheimer’s Disease in Paris.

A team of researchers from the Texas Alzheimer’s Research and Care Consortium (TARCC) has found that biomarkers in blood serum could be combined with clinical information to accurately classify patients with Alzheimer’s disease. Sid E. O’Bryant, Ph.D., led the TARCC team that developed the test.

Simple, Accurate Test

O’Bryant said the test refines a previous blood test and has shown to be effective when cross-validated against another sample group.

“Basically we created a simpler version of a recent blood test,” O’Bryant said. “We created a briefer screen test in the TARCC cohort and then applied it to the Alzheimer’s Disease Neuroimaging Initiative (ADNI) national cohort and found we still accurately identify 88 percent of those with and without the disease.”

ADNI is a research project to study the rate of change of cognition, function, brain structure and biomarkers. The project was funded with $40 million from the National Institutes of Health, and $20 million from pharmaceutical companies.

The TARCC screen test represents many firsts for the potential diagnosis of Alzheimer’s. First, no other such test has ever been cross-validated in an independent cohort. Second, this version of the screen test works with different sorts of blood draws making it easier for clinics to implement. Third, to date, no prior work has explicitly sought to find blood-biomarkers of Alzheimer’s across both serum and plasma and no previous attempts at identifying blood-based screening tools have utilized markers across blood fractions.

Reliable, Easy-to-Obtain Samples

“There is clearly a need for reliable and valid diagnostic and prognostic biomarkers of Alzheimer’s disease,” O’Bryant said. “Identifying biomarkers in the blood has several advantages over other methods of classifying patients with Alzheimer’s disease, including detecting biomarkers in the cerebrospinal fluid and neuroimaging. Blood can be collected at any clinic or in-home visit, whereas not all facilities can conduct lumbar punctures to obtain cerebrospinal fluid. Older patients may not consent to lumbar puncture and may not be able to undergo neuroimaging because of pacemakers or other health issues."

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The team’s analysis of serum biomarker proteins were conducted on 197 participants with Alzheimer’s disease and 199 control participants of the TARCC cohort with further analysis conducted on plasma proteins from 112 Alzheimer’s disease and 52 control participants from the ADNI cohort.

A recent article in The Boston Globe highlighted the need to test potential Alzheimer’s medicines on patients who have beta amyloid, an abnormal protein associated with the disease, but who have not yet manifested Alzheimer’s. Much as patients with high cholesterol are given medication to ward off a heart attack or stroke, preventatively administering new medicines to patients with this protein may delay onset and slow progression of Alzheimer’s disease. The TARCC test is a potentially critical tool in effectively identifying such individuals.

While a Food and Drug Administration working group recently gave preliminary approval for a neuroimaging technique to detect beta amyloid as a biological marker, no blood-based biomarker screening tool has received approval to date.

The purpose of the TARCC study was to generate a blood-based screen for Alzheimer’s disease that can be incorporated into existing medical practice, with more detailed assessment then provided to confirm the disease in those who screen positive in the blood test.

“In the last several years, there have been significant advancements in the search for blood-based biomarkers for Alzheimer’s disease,” O’Bryant said. “Together, these studies suggest that a blood-based screening tool for Alzheimer’s disease is on the horizon.”

The full study can be found here.