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Alzheimer’s Blood Test Guidelines Aim to Standardize Clinical Use

Sep 3, 2025 | Laboratory News, Laboratory Pathology, Laboratory Testing

New recommendations from the Alzheimer’s Association call for Alzheimer’s blood tests to reach at least 90% sensitivity and specificity to be used in place of established diagnostic tools.

Alzheimer’s blood tests need to offer at least 90% sensitivity and 90% specificity before they can replace brain scans and spinal taps in diagnosis of the neurodegenerative disease, according to a new clinical practice guideline recommendation from the Alzheimer’s Association.

The health organization cautioned in a news release that “many commercially available blood-based biomarker tests do not meet these thresholds” for substituting amyloid PET imaging and cerebrospinal fluid (CSF) tests in Alzheimer’s diagnosis.

“The whole purpose of developing the clinical practice guideline is to try to create pragmatic recommendations for clinicians on how to choose the right test for the right patient at the right time,” Rebecca Edelmayer, PhD, Alzheimer’s Association Vice President of Scientific Engagement, told Medscape. “The blood- based biomarker area is still a burgeoning field,” added Edelmayer, a guideline Co-author.

Clinical laboratories may find the recommendations useful in making decisions about additions to lab test menus and in educating clinicians on appropriate test ordering.

Pathological Signs of Alzheimer’s

Edelmayer and colleagues published the guideline in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, entitled, “Alzheimer’s Association Clinical Practice Guideline on the Use of Blood-Based Biomarkers in the Diagnostic Workup of Suspected Alzheimer’s Disease Within Specialized Care Settings.”

“Pathologically, Alzheimer’s disease is defined by the accumulation of extracellular cortical plaques composed of amyloid-beta fibrils and intracellular neurofibrillary tangles containing abnormal hyperphosphorylated tau protein. These pathologies manifest many years or even decades before the onset of clinical symptoms,” the authors wrote.

Compared to “standard-of-care” amyloid PET imaging and CSF tests, blood-based biomarkers may cost less and reduce patients’ stress, the Alzheimer’s Association pointed out, adding that blood tests are not a replacement for clinical evaluations by healthcare providers.

“What we’ve learned from all of the evidence so far is that some of these biomarkers, like tau217, tend to be very accurate predictors of Alzheimer’s disease biology in the brain, and they can be used to aid in the diagnostic process early on—sometimes even before tau tangle formations can be visualized with brain imaging,” Rebecca Edelmayer, PhD, Alzheimer’s Association Vice President of Scientific Engagement, said in the Medscape article. (Photo credit: Alzheimer’s Association.)

Panel Reviews Phosphorylated-tau and Amyloid-beta

To discover the diagnostic accuracy of blood-based biomarkers in Alzheimer’s disease, a panel of 11 clinicians, convened by the Alzheimer’s Association, did a systematic review using this methodology described in the association’s statement:

  • Reviewed 49 observational studies and assessed 31 tests.
  • Focused on blood-based biomarkers including plasma phosphorylated-tau (p-tau) and amyloid beta (Aβ) tests measuring: p-tau217, ratio of p-tau217 to non-p-tau217 x 100, p-tau181, p-tau231, and ratio of Aβ42 to Aβ40.
  • Applied Grading of Recommendations Assessment, Development, and Evaluation  (GRADE) to “evaluate certainty of evidence” and aid development of recommendations.
  • Panelists, unaware of the tests they were reviewing, did not rank or endorse tests. 

Diagnostic accuracy varied among the assays with sensitivity ranging from 49.31% to 91.41% and specificity from 61.54% to 96.72%, Neurology Advisor reported.

Tests evaluated included these, which were also recently reported on by Dark Daily:

Elecys by Roche, Lumipulse created by Fujirebio, and Precivity from C₂N Diagnostics.

Advice for Using Alzheimer’s Blood Tests

Based on the systematic review, the panel released the following recommendations for use of blood-based biomarker tests when Alzheimer’s disease is suspected, according to the Alzheimer’s Association:

  • Tests with 90% sensitivity and 90% specificity or more may stand-in for PET amyloid imaging or CSF Alzheimer’s biomarker testing.
  • Tests with at least 90% sensitivity and 75% specificity can serve as triaging assays whereby negative results rule out Alzheimer’s “with high probability” while positive findings need confirmation with PET or CSF testing.  

“For the first time, we have a rigorously evidence-based guideline that empowers clinicians to use blood biomarker tests confidently and consistently.  Adoption of these recommendations will lead to quicker, more accessible, more accurate diagnoses, and better outcomes,” said Maria Carillo, PhD, Alzheimer’s Association Chief Science Officer and Medical Affairs Lead and a Co-author of the guideline.

The guideline is part of the Alzheimer’s Association resources to promote best practices. It plans development of other reports about cognitive assessment tools, clinical implementation of staging, and Alzheimer’s prevention.

—Donna Marie Pocius

FDA Grants First-Ever Clearance of Clinical Laboratory Blood Test for Alzheimer’s Detection

Jun 23, 2025 | Laboratory Instruments & Laboratory Equipment, Laboratory News, Laboratory Pathology, Laboratory Resources, Laboratory Testing, Precision Medicine

Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio test measures blood biomarkers associated with the disease

Clinical laboratories could soon find themselves playing a significant role in Alzheimer’s care as the US Food and Drug Administration (FDA) announced its first-ever clearance of a blood test to assist in diagnosing the cognitive disease.

The agency issued a 510(k) clearance for the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio test from Fujirebio Diagnostics, Inc. The test is intended for “the early detection of amyloid plaques associated with Alzheimer’s disease in adult patients, aged 55 years and older, exhibiting signs and symptoms of the disease,” according to an FDA press release.

“Nearly seven million Americans are living with Alzheimer’s disease, and this number is projected to rise to nearly 13 million,” said FDA Center for Devices and Radiological Health Director Michelle Tarver, MD, PhD, in the press release. “Today’s clearance is an important step for Alzheimer’s disease diagnosis, making it easier and potentially more accessible for US patients earlier in the disease.”

“Alzheimer’s disease impacts too many people, more than breast cancer and prostate cancer combined,” said FDA Commissioner Martin A. Makary, MD, MPH, in the FDA press release.

“Knowing that 10% of people aged 65 and older have Alzheimer’s, and that by 2050 that number is expected to double, I am hopeful that new medical products such as this one will help patients,” said FDA Commissioner Martin A. Makary, MD, MPH, in the FDA press release. (Photo copyright: Johns Hopkins University.)

Blood Protein Test Details

Fujirebio’s test calculates the ratio of two blood proteins, pTau217 and β-amyloid 1-42. “This ratio is correlated to the presence or absence of amyloid plaques in the patient’s brain, reducing the need for a PET scan,” the press release states.

The FDA said it has already authorized or cleared similar tests that use cerebrospinal fluid (CSF) samples obtained through an invasive spinal tap. “This new Lumipulse test only requires a simple blood draw, making it less invasive and much easier for patients to access,” the FDA said.

In granting the clearance, the agency looked at data from a clinical study of 499 adults displaying signs of cognitive impairment. Close to 92% of participants with positive test results had amyloid plaques as determined by amyloid PET scan or CSF test results. Approximately 97% with negative results from the Lumipulse test were also shown to be negative in the PET scan or CSF test. Fewer than 20% of the patients received indeterminate results, which would require additional testing.

The primary risks of the test are false positive or false negative results, the federal agency noted.

“Importantly, the Lumipulse G pTau217/ß-Amyloid 1-42 Plasma Ratio is not intended as a screening or stand-alone diagnostic test and other clinical evaluations or additional tests should be used for determining treatment options,” the FDA said.

‘Wild West’ Marketplace

In their reporting of this story,MedPage Today and the Associated Press both noted that some laboratory-developed tests can already measure plasma biomarkers associated with Alzheimer’s.

“But those tests aren’t reviewed by the FDA and generally aren’t covered by insurance,” the AP reported. “Doctors have also had little data to judge which tests are reliable and accurate, leading to an unregulated marketplace that some have called a ‘wild west.’”

Neurologist Richard S. Isaacson, MD, told CNN that he’s already using the test for research purposes. “It can provide better clarity into whether a person experiencing memory loss may have Alzheimer’s disease,” he said.

However, he cautioned that more research is needed to allow doctors to make best use of the test.

“I think the next step as a field is, we need to advance education about what these tests mean and what they don’t and who they should be used for,” he told CNN. “Because they mean different things in different people depending on their risk factors and whether they have symptoms. So, we’re still early.”

“The results must be interpreted in conjunction with other patient clinical information,” the FDA acknowledged in their press release.

Other Alzheimer’s Tests

The FDA said it reviewed the Lumipulse test through the 510(k) premarket notification pathway, in which the federal agency determines if a device is “substantially equivalent to a legally marketed predicate device.”

In this case, the agency found that the test is substantially equivalent to Fujirebio’s Lumipulse G β-amyloid Ratio (1-42/1-40), which measures the same proteins in CSF samples. The FDA authorized that device in 2022, according to a Fujirebio press release. That test uses Fujirebio’s automated Lumipulse G1200 instrument system.

Other companies including Roche, Eli Lilly, and C2N Diagnostics are also developing Alzheimer’s tests they intend to submit for FDA review, the AP reported.    

—Stephen Beale

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