The People's Perspective on Medicine

New Blood Test for Alzheimer Disease

Scientists hope that a blood test for Alzheimer disease that measures a protein resulting from nerve cell breakdown will permit early diagnosis.
Male technician analyzing blood sample in medical laboratory

Detecting Alzheimer disease is complicated. There are no simple tests. Doctors can perform cognitive function evaluations and order brain imaging, but to date definitive diagnosis relies on autopsy examination. Now, however, a new blood test for Alzheimer disease may allow for early diagnosis.

What Is the Blood Test for Alzheimer Disease?

Researchers report that a blood test may be able to detect signs of neuron degeneration many years before symptoms appear (Preische et al, Nature Medicine, Jan. 21, 2019). The investigators published their findings in Nature Medicine. For this ground-breaking research, they utilized an unusual group of volunteers, including 247 people who had a genetic risk for early-onset Alzheimer disease. Importantly, those who had this particular rare genetic marker were predestined to show symptoms of dementia at approximately the same age as their nearest relatives with the disease. The scientists matched these individuals to family members without the genetic marker. All the subjects gave blood, performed cognitive tests and underwent imaging scans.

A Special Protein Appears in the Blood Test for Alzheimer Disease:

The researchers analyzed the participants’ blood for a protein called neurofilament light chain that is released when brain cells disintegrate. The people with a gene for early Alzheimer disease had higher protein levels when first tested. Moreover, their levels of neurofilament rose steadily over time. The other participants had steady low levels of the protein.

Differences in the protein were detectable sixteen years before the expected onset of symptoms. Rapid increases in neurofilament light chain levels were also linked to brain shrinkage visible on scans. This preliminary test is not yet ready for clinical use, but the authors hope that it will someday allow doctor to diagnose Alzheimer disease when intervention might still make a difference.

Learn More:

This new blood test for Alzheimer disease will be welcome if it actually assists with early diagnosis. Some specialists are already using a variety of tests to determine if someone may be vulnerable to this devastating condition and, most importantly, to treat the factors that contribute to cognitive dysfunction. To learn more, you may wish to listen to our interview with Dr. Dale Bredesen. It is Show 1092: How Can You Overcome Alzheimer Disease?

You may also wish to read about other new tests being developed to detect Alzheimer disease early, including a type of MRI called diffusion tensor imaging.  Special retinal imaging called optical coherence tomography angiography also shows promise for early diagnosis of Alzheimer disease.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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Yes, I’d like to know if I’m a potential Alzheimer’s victim, especially since I’ve been reading about this new nasal spray that is supposed to reverse it. It’s not yet on the market, but if I found I have the potential for the disease, I’d volunteer to be a test case for the spray.

One of my siblings had already passed this info on and I didn’t know how to say that I absolutely don’t want to know. At best I would spend my remaining years worrying that I am not doing enough to retain my mind; and at worst they will find out that either this isn’t the “answer” or that I am still too late to save myself. Sometimes ignorance is best….however I do keep up on how diet, exercise and other affect my chances of avoiding Alzheimers disease unlike my mother, grandfather, aunt…

Knowing several people with Altzheimers and dementia, all of whom have been told by their doctors that there is basically nothing that can be done, what is the value of early detection?

There are medications that slow the progression of dementia which could be the value of early detection.

Is the protein only released by disintegrating brain cells? If this test can detect signs of neuron degeneration, I wonder whether it can help with diagnosing nerve diseases in areas of the body other than the brain.

I am not sure that I would want to know. Kind of like knowing the day you will die. And call me paranoid, but I am concerned that the health and life insurance companies would end up using the results against me to raise my rates or cancel my coverage.

Wondering if other factors such as alcohol use, drugs/medication, or possibly environmental exposures, e.g. gasoline or other toxins, may also cause release of this light chain protein?

I’ve met people who say that they don’t want to know if they’re headed for Alzheimer’s disease because there’s nothing they can do about it. So I tell them about Dr. Bredesen’s book, “The End of Alzheimer’s,” and his interview on the People’s Pharmacy show. I like to think of his list of factors that he used to reverse Alzheimer’s as a checklist for all the things that are in my control to PREVENT heading toward Alzheimer’s. After putting his factors into checklist form, I’ve already checked off quite a few that I’ve been able to reverse and have found that my multiple “senior moments” a day have been reduced significantly!

Should this be successful, why get diagnosed with something they cannot treat?

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