A new blood test promises to help detect Alzheimer’s disease, the most common type of dementia. Photo by Amornthep Srina from pexels.com
A new blood test in development by researchers in the United States, Sweden, and Canada promises to give physicians an inexpensive, comfortable, and more precise tool to help them diagnose the leading form of dementia: Alzheimer’s disease.
As the population ages, it is no surprise that Alzheimer’s is the most prevalent neurodegenerative disease worldwide, afflicting more than 44 million people. With an increased number of cases and limited treatments, it would be beneficial to detect Alzheimer’s early for a better prognosis.
Currently, Alzheimer’s is detected through visible symptoms such as frequent forgetfulness, poor decision making, mood changes, and losing track of time. Once referred to a neurologist, a patient suspected of having Alzheimer’s may endure painful spinal infusions, uncomfortable and claustrophobic MRI and PET chambers, and various other invasive tests.
Thoroughly going through all the requirements for a proper Alzheimer's diagnosis takes time. It almost seems surreal that a simple blood test could diagnose a disease with such a reputation for a lengthy and difficult process of diagnosis.
Not only would it be better to detect Alzheimer’s for better control of the disease, but it would also allow for a less invasive and timely procedure than to what is currently being offered.
Tau is a key indicator of Alzheimer’s disease and therefore this blood test. Here’s why.
Tau is a phosphorylated protein. This in itself is normal; phosphorylation is a chemical change that is involved in cell growth, cell signalling, and apoptosis (that is, telling a cell to die when it has reached the end of its normal life cycle). Specifically, it is when a phosphoryl group (composed of one phosphorus and three oxygen atoms) is added to proteins that contain the amino acids threonine, tyrosine and serine.
When phosphorylation goes awry for the Tau protein, it aggregates into clumps known as neurofibrillary tangles. These tangles are the primary indicator for Alzheimer's disease. It is thought that the onset of disease begins when Tau is phosphorylated at certain Alzheimer’s-prone sites.
For their blood test, the researchers measure the concentration of ptau181, a version of Tau that is phosphorylated at a specific site (181) on the protein.
Using this measurement, they were able to see the difference in protein levels between the blood of healthy individuals and that of people with Alzheimer's. This test is being compared with PET scans and spinal fluids to ensure the results were in fact positive and accurate.
While the results are promising the blood test is still in development and likely years from release.
If it does make the grade, this test will be of great value in primary care settings. Individuals with a family history of Alzheimer’s could easily request the test to get an indication of early cognitive impairment.
This test could also provide a simpler and more accessible way for known Alzheimer’s patients to follow the progression and prognosis of the disease.
To be sure, there are still many trials that need to take place to ensure safety and accuracy of this test, but knowing that future and current generations may have better tools to control and prolong their quality of life is science worth celebrating.
By: Roxaneh (Roxana) Zaminpeyma
Roxana is a McGill graduate who holds a Bachelor’s degree in Anatomy and Cell Biology with a minor in Social Studies of Medicine. She is currently a candidate for a Masters in Experimental Surgery at McGill. She is an aspiring clinician-scientist who is passionate about immunology, neurodegenerative research, patient advocacy, humane caregiving as well as medical history and technology. Her goal is to translate scientific content into words and images that can bring understanding to all her readers.