“Far more than a senior moment, Alzheimer’s disease (AD) is the “Long Goodbye.” The disease is not a part of normal aging. It is a gradual, deadly assault on memory, reasoning and behavior. It cripples a person’s emotional, mental and physical health.
More Americans than ever fear Alzheimer’s disease, and for good reason. Once a person is in the grasp of this disease, it relentlessly proceeds towards a mindless, incapacitating ending. There is no cure for it at present, and no one is spared the trauma of this disease.
It affects 10% of Americans over the age of 65, and 65% of the cases are women. As of March 2024, an estimated 6.9 million Americans aged 65 and older are living with Alzheimer’s dementia. This number is expected to grow significantly in the coming years.
Research is actively pursuing a cure, and better tests to identify this condition. A diagnostic blood test for Alzheimer’s was recently reported in JAMA for this most common type of dementia.
The exact cause of this neurological disease is not fully understood. Nerve cells, called neurons, connect to transmit information to and from the brain. In people with Alzheimer’s disease, proteins build up and form structures that disrupt communication between neurons in the brain. This protein buildup causes brain cells to die, and brain tissue to shrink in size. Two proteins have been linked to AD, and referred to as two hallmarks as causing this disease, Plaques and Tangles.
Plaques are clumps of abnormal proteins called beta-amyloids created from a buildup of protein fragments. They occupy the space between neurons (brain cells) and prevent the neurons from communicating normally with each other.
Tangles are accumulations of proteins called tau that form twisted fibers inside the neurons themselves. This prevents molecules and information from traveling normally within the cell. “Might there be a test to identify Plaques and Tangles before they actually appear in the brain?”
Blood Test to Predict Alzheimer’s Disease
A blood test to predict AD was reported by researcher Shorena Janelidze, Lund University Sweeden, and colleagues in JAMA Neurology on July 28, 2024, which described how a single blood sample is used to predict the risk of developing Alzheimer’s disease in people without cognitive impairment. The researchers answer the question: “Which plasma biomarkers are useful to predict the future development of Alzheimer’s disease?”:
The authors answered this question by using blood plasma biomarkers (specifically p-tau217 and the beta-amyloid ratio — Aβ42/40 ratio) to measure protein accumulation levels of amyloid plaques and tau tangles in the brain. The accumulation of such plaques and tangles is a hallmark of Alzheimer’s disease.
The study found that by utilizing the results of both biomarkers, one could effectively predict the likelihood of tau and beta-amyloid pathology, and therefore, Alzheimer’s disease, before they reach clinically detectable stages. The new blood test, by combining both plasma biomarkers, can predict Alzheimer’s disease with an accuracy of 88 to 92%, as well as outperforming clinical evaluations.
The takeaways from this study is that a simple blood test to measure protein biomarkers in the brain is another tool in the doctor’s bag that physicians have in diagnosing, and treating Alzheimer’s disease. The blood test promises to diagnose early memory loss, classify individuals as low, intermediate, or high risk for this disease, increase diagnostic accuracy for AD, and monitor treatment protocols as to their effectiveness. The authors suggest that future studies should include preventive measures for individuals identified at high risk of developing Alzheimer’s disease.
Addendum
Blood tests are screening tools for Alzheimer’s which are less expensive than spinal taps, and brain scans. However, they’re not fully definitive (diagnostic) yet, and the test results should be confirmed with a PET scan , or spinal tap.
References
- Shorena Janelidze et al; Plasma Phosphorylated Tau 217 and AB42/40 To Predict Early Brain AB Accumulatio in People Without Cognitive Impairment; JAMA Neurol., Sept 1, 2024
- Joseph R. Anticaglia, MD; “The Long Goodbye” — The Five Stages of Alzheimer’s Disease; Doctors Column HC Smart, March 2018
- Alzheimer’s Association Report; 2024 Alzheimer’s disease facts and figures; April 30, 2024
- Joseph R. Anticaglia, MD; Alzheimer’s Disease A Healthcare Tsunami;, MD; Doctors Column HC Smart, February 2018
This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.