Straight Dope on Medicine: Razzle Dazzle Alzheimer's Test

Author

Scott Ganser
February 12, 2024

  • There are 10.7% or 6.5 million Americans (65 and over) living with Alzheimer’s in 2022.[i]

  • Every 65 seconds, one person in the US develops Alzheimer’s disease.

  • The number of individuals living with Alzheimer’s disease can increase to 13.8 million by 2060.

  • 4 million women (12%) and 2.5 million men (9%) have Alzheimer’s disease.

  • 72.9% (4.72 million) of the total Alzheimer’s cases in the US are people aged 75 and above.

  • 82,965 people die from Alzheimer’s and its complications each year.

  • 12% to as high as 70% of dementia patients die from pneumonia.

  • The cost of Alzheimer’s disease in the US will amount to $321 billion by the end of 2022.

Why all the excitement?

New Blood Test Identifies Alzheimer’s With 97% Accuracy

This test is more appealing than previous tests. Today, people who suspect they have Alzheimer’s disease tend to undergo invasive, uncomfortable, and costly brain scans or spinal taps before they receive a diagnosis. By then, symptoms have already begun to surface, offering them and their families less time to make necessary healthcare and lifestyle adjustments. But what if doctors could spot Alzheimer’s in patients before they begin to experience memory loss? 

Only about 2% of potential patients take the currently available tests.

That’s the idea behind a new blood test made by ALZpath, a California-based medical diagnostics company. Called the ALZpath pTau217 (Phosphorylated tau) assay, the test is currently available exclusively to research entities, who are busy verifying the test’s efficacy with people at risk of developing Alzheimer’s. In a study examining the results of three Alzheimer’s study cohorts, researchers at Sweden’s University of Gothenburg found that the pTau217 assay is highly accurate and could be ready for clinical research soon.

“And that is a revolutionary change,” says Paul Newhouse, M.D., director of the Center for Cognitive Medicine at Vanderbilt University Medical Center and clinical core leader for the Vanderbilt Alzheimer’s Disease Research Center.

P-tau can also be found in tears.

In a nutshell, the new test will be a better experience (and less expensive) while simultaneously being far superior in accuracy and predictability.

Tau and amyloid β-protein (Aβ) are known to accumulate in the brains of people with Alzheimer’s, making them both valuable biomarkers when it comes to Alzheimer’s diagnosis; however, p-tau217 tends to outperform other Alzheimer’s-related biomarkers when blood plasma is the testing medium.

The University of Gothenburg’s longitudinal study found that the pTau217 assay correctly identified elevated levels of tau 97% of the time, making it an incredibly accurate diagnostic tool. The test also tracked participants’ p-Tau217 levels as they increased over the years, allowing for “improved patient management and, ultimately, timely access to disease-modifying therapies,” the researchers note.

The Competition

EXPOSURES Magnetic resonance imaging, Aβ positron emission tomography (PET), tau PET, cerebrospinal fluid (CSF) biomarkers (Aβ42/40 and p-tau immunoassays), and plasma p-tau217 (ALZpath pTau217 assay)[ii]

PET imaging can cost more than $3,000 a scan and is not usually covered by insurance.[iii]

The AD-Detect blood test, which assesses the risk of Alzheimer’s disease (AD) pathology in adults with mild cognitive impairment (MCI) or dementia, is now available directly to consumers. The cost for the AD-Detect test is $399, plus a $13 physician service fee.[iv]

These aren’t the droids you are looking for.

Sorry, this isn’t the blood test we are looking for.

This is the antecedent blood test. The stellar one is not yet available.

FDA Approves Fujirebio’s CSF Test for AD—Quest Diagnostic Offers Plasma Test

21 May 2022

The Food and Drug Administration issued its first approval for a fluid biomarker test May 4, greenlighting Fujirebio’s Lumipulse G cerebrospinal fluid Aβ42/40 assay. This approval will enable broad clinical usage and ensure more consistent insurance coverage.

Diagnostics are big business.[v]

Many other Alzheimer’s diagnosis and treatment options are underway, too. An electroencephalography (EEG) headband developed in 2023 appears to reliably monitor users for signs of the disease by spotting brain wave “spindles.” A drug produced by pharmaceutical giant Eli Lilly could help delay the onset of severe Alzheimer’s symptoms, while a peptide engineered at MIT might minimize symptom occurrence. Last year, a common bodybuilding supplement was identified as a potential agent against cognitive decline. And to prevent memory loss in the first place, an international team of researchers is working on developing an Alzheimer’s vaccine.


REFERENCES

[iii] Mitka M. Pet imaging for Alzheimer's disease: are its benefits worth the cost?. JAMA. 2013;309(11):1099. doi:10.1001/jama.2013.2101