The use of blood tests to determine an individual’s likelihood of developing Alzheimer's disease is inching closer to clinical use, according to a new study published Monday in the Journal of the American Medical Association.

Researchers found that a commercially available blood test for p-tau217 — a key biomarker of the disease — was as accurate as one using a more invasive cerebrospinal fluid test or brain scan.

What You Need To Know

  • Blood tests that screen for a biomarker of Alzheimer's disease are getting closer to clinical use

  • A study published Monday in the Journal of the American Medical Assn. found blood tests were as accurate as more invasive cerebrospinal fluid tests or brain scans

  • The buildup of p-tau217 in the blood indicates manifestation and progression of Alzheimer's

  • A blood test was able to accurately identify p-tau217 up to 97% of the time

The National Institutes of Health found the buildup of p-tau217 in the blood indicates the manifestation and progression of Alzheimer’s disease, which leads to brain atrophy and physical degradation. About 5.8 million people in the United States have Alzheimer’s disease, according to the Centers for Disease Control. The most common type of dementia, Alzheimer’s is expected to affect 14 million Americans by 2060.

According to the JAMA study, the blood test was able to accurately identify p-tau217 up to 97% of the time. The ALZpath p-tau217 assay, as the test is known, was provided to the researchers for free by ALZpath, the company that developed it. The test is not yet available for clinical use but is expected to be available soon for an estimated cost of $200 to $500.

“A robust and accurate blood-based biomarker would enable a more comprehensive assessment of cognitive impairment in settings where advanced testing is limited,” the researchers wrote in JAMA. “Use of a blood biomarker is intended to enhance an early and precise AD diagnosis, leading to improved patient management and, ultimately, timely access to disease-modifying therapies.”

The findings were based on three cohorts, some of whom participated in years-long studies. The 786 participants had a mean age of 66.3 and included a mix of those who did and did not have cognitive impairment. Over the course of eight years, the study found the largest change of p-tau217 was in individuals who had tested positive for it along with another biomarker known as beta amyloid.

The researchers noted that p-tau demonstrates “superior diagnostic accuracy and disease specificity” and is “the primary blood biomarker for Alzheimer disease pathology throughout all stages of the disease.”

While the majority of U.S. Alzheimer’s disease patients are 65 and older, about 200,000 have younger onset.