A Simple Blood Test For Alzheimer’s Detection

A neurologist may not immediately be able to determine whether a patient’s complaints of forgetfulness are due to normal aging, decreased blood flow to the brain, or, more concerningly, Alzheimer’s disease. An autopsy has been the only conclusive diagnosis of Alzheimer’s for much of the past century.

Today, it is possible to detect the disease in patients even before the first symptoms show up owing to the spinal fluid and brain imaging tests. However, due to their high cost, these invasive tests are typically restricted to research settings and not routinely provided to the millions of people who suffer from the most prevalent neurodegenerative disorder.

Scientists have been trying to find cheaper and easily accessible blood tests to diagnose Alzheimer’s as an alternative to expensive tests and brain scans. In such an attempt, researchers at Washington University School of Medicine in St. Louis developed a highly accurate blood test that can detect early signs of Alzheimer’s in combination with the genetic risk factor. C2N Diagnostics made the test, known as PrecivityAD^TM, available commercially to most of the U.S. in fall 2020, regulated under the CMS Clinical Laboratory Improvement Amendments (CLIA) program.

PrecivityAD^TM Test

The PrecivityAD^TM blood test utilizes the mass spectrometry technique to detect specific types of beta-amyloid proteins. Beta-amyloid, the pathological hallmark of Alzheimer’s disease, accumulates and forms plaques in the brain that become visible on brain scans about two decades before the patient notices memory issues.

Beta-amyloid levels in the surrounding fluid decrease as plaques build up in the brain. Spinal fluid samples and, more recently, blood, where beta-amyloid levels are noticeably lower, can detect these changes. PrecivityAD ^TM – one of the new generations of such assays – is the first blood test for Alzheimer’s to be approved for widespread use. It may be able to detect the most common neurodegenerative disease decades before the onset of the initial symptoms.

The blood test determines whether amyloid plaques have started depositing in the brain based on the ratio levels of the amyloid-beta proteins, Aβ42 and Aβ40, in the blood. The test’s overall agreement with brain amyloid PET to determine whether amyloid plaques are present or absent is about 86 percent. This result comes from a single blood draw combined with a person’s age, APOE genotype, and blood ratio of A42/40.

CLIA certification makes the test available to doctors in America. The information provided intends to assist in the medical assessment and treatment of patients already exhibiting signs of cognitive decline. In Europe, the test is accessible through a similar certification. Most health insurance plans do not currently cover this test.

A Comparatively Cost-Effective Test

A radioactive brain scan is necessary to evaluate the disease using PET brain scans, which are still the gold standard. These scans typically cost between $5,000 and $8,000 each. Another usual test, which costs about $1,000 but necessitates a spinal tap procedure that some patients might find uncomfortable, measures the amount of amyloid-beta and tau protein in cerebrospinal fluid (CSF).

The simplicity and lower cost of blood tests than the more invasive and taxing procedures create an array of exciting opportunities for clinical use and therapeutic development.

In clinical trials, participants frequently have to provide PET scans or CSF measurements as proof of disease pathology. According to a study¹, prescreening with a $500 blood test could cut the expense and time required to enroll patients in clinical trials using PET scans in half. Screening that relies solely on blood tests could be finished in less than six months while saving at least ten times as much money. Lowering the costs of trials means more opportunities to discover potential treatments.

Alzheimer’s Research Association is a non-profit organization dedicated to helping caregivers of Alzheimer’s disease and dementia. We provide the latest information and news about the illness and helpful tips to help caregivers cope with their daily caregiving challenges. We realize the most important thing that a caregiver needs is financial assistance. Therefore, we provide grants to caregivers to ease their financial burden. Caregivers can apply for grants here: https://www.alzra.org/grant-applications/.

You can also help caregivers in their endeavor by donating as much as possible: Donations to Alzheimer’s Association.

References

1.      Keshavan, A., Pannee, J., Karikari, T.K., Rodriguez, J.L., Ashton, N.J., Nicholas, J.M., Cash, D.M., Coath, W., Lane, C.A., Parker, T.D. and Lu, K., 2021. Population-based blood screening for preclinical Alzheimer’s disease in a British birth cohort at age 70. Brain, 144(2), pp.434-449. https://pubmed.ncbi.nlm.nih.gov/33479777/.

2.      Li, Y., Schindler, S.E., Bollinger, J.G., Ovod, V., Mawuenyega, K.G., Weiner, M.W., Shaw, L.M., Masters, C.L., Fowler, C.J., Trojanowski, J.Q. and Korecka, M., 2022. Validation of plasma amyloid-β 42/40 for detecting Alzheimer disease amyloid plaques. Neurology, 98(7), pp.e688-e699. https://pubmed.ncbi.nlm.nih.gov/34906975/.