In studies, blood tests to detect Alzheimer’s are showing promise: over the course of years of testing, they are proving to be accurate means of detecting the disease years before symptoms appear. Now, scientists are working to ensure they will be affordable. And this process takes time.
Multiple blood tests are in development, the newest under the leadership of researchers at the University of Gothenburg, Sweden. Based on measurement of a specific variant of tau proteins in ordinary blood samples, it is relatively simple and cheap to perform, according to a new study in the The Lancet Neurology. The test produces results similar to those from another blood test in development by Eli Lilly, on which one of this test’s developers also collaborated.
This specific variant of tau — P-tau181 — is greatly elevated in patients with the beta-amyloid plaques that indicate Alzheimer’s, even at the diseases’s earliest visible stage, mild cognitive impairment. Other blood tests for tau may also be coming to market, but this newest one is relies on a method called Single Molecule Array (Simoa), which can measure much lower levels of protein biomarkers than other analytical methods.
According to the research, the test was able to distinguish Alzheimer’s from other neurodegenerative diseases — for example, frontotemporal dementia and Parkinson’s disease — in which the blood level of P-tau181 was normal.
The medical and scientific community know a faster, easier, more accessible means of diagnostic testing is a dire piece of the puzzle when it comes to finding an Alzheimer’s cure.
“Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years,” Dr. J. Bateman, a professor of neurology at the Washington University School of Medicine, told Science Daily in 2019. “But with a blood test, we could potentially screen thousands of people a month. That means we can more efficiently enroll participants in clinical trials, which will help us find treatments faster, and could have an enormous impact on the cost of the disease as well as the human suffering that goes with it.”
Existing Alzheimer’s tests that focus on P-tau181 have measured the protein in cerebrospinal fluid, where it is found in higher quantities, but these tests are difficult and not everyone has access to a specialist who can conduct them. Meanwhile, advanced PET scans have been used, but these can be costly. So when the tests to get to market, they will be relatively affordable and minimally invasive.
So, How Do I Get a Blood Test for Alzheimer’s?
So far, blood tests are only available by way of clinical trials, and in March 2020, researchers estimated these tests are still five years away from being available among the blood tests conducted at your doctor’s office.
In part, this is because the testing process must unfold over the course of years. As Dementia Care Central puts it, “If the researchers are hoping to identify the condition three years in advance of showing symptoms, then they must wait three years to determine if the test is working. If it is not, they start all over again. If they hope to identify the disease 10 years before symptoms, then they must wait 10 years.”