Blood Test Method May Predict Alzheimer’s Protein Deposits in Brain
March 3, 2020

Researchers have developed a blood test that could help detect pathological Alzheimer’s disease in people who are showing signs of dementia.

The approach, described in Nature Medicine,could be less invasive and less costly than current brain imaging and spinal fluid tests. The blood test detects the abnormal accumulation of a form of tau protein known as phosphorylated-tau-181 (ptau181), which is a biomarker that suggests brain changes from Alzheimer’s disease.

Tau and other biomarkers can be detected with positron emission tomography (PET) scans of the brain and lab tests of spinal fluid. However, PET imaging is expensive and involves radioactive agents, and spinal fluid tests require spinal taps, which are invasive, complex and time-consuming. Therefore, simpler biomarker tests are still needed.

“The considerable time and resources required for screening research participants with PET scans and spinal taps slow the pace of enrollment for Alzheimer’s disease treatment studies,” said Richard J. Hodes,MD, National Institute on Aging, part of the National Institutes of Health (NIH), Bethesda, Maryland. “The development of a blood test would enable us to rapidly screen a much larger and more diverse group of volunteers who wish to enroll in studies.”

An international team of researchers led by Adam Boxer, MD, University of California at San Francisco (UCSF), San Francisco, California, used the new test to measure the concentration of ptau181 in plasma, which is the liquid part of blood that carries the blood cells. The samples were collected from more than 400 participants from the UCSF Memory and Aging Center.

Their analysis demonstrated that the ptau181 in plasma could differentiate healthy participants from those with Alzheimer’s pathology, and differentiate those with Alzheimer’s pathology from frontotemporal lobar degeneration (FTLD).

“It has become clear that there are many possible biological pathways to dementia,” said Roderick Corriveau, PhD, National Institute of Neurological Disorders and Stroke, part of the NIH. “Finding a blood test that specifically identifies the presence of Alzheimer’s pathology in the brain should greatly help researchers develop better treatments for the many who suffer from dementia.”

A different international team, led by Oskar Hansson, MD, Lund University, Lund, Sweden, reported similar findings, also published in Nature Medicine. Using the same plasma ptau181 test, the researchers were able to differentiate between Alzheimer’s and other neurodegenerative diseases nearly as well as they could with a spinal fluid ptau181 test and a PET brain scan for tau protein. In addition, they followed participants for several years and observed that high levels of plasma ptau181 among those who were cognitively normal or had mild cognitive impairment may be used to predict later development of Alzheimer’s dementia.

Reference: https://www.nature.com/articles/s41591-020-0755-1

SOURCE: National Institutes of Health