A new blood test could revolutionize the diagnosis and treatment of Alzheimer’s. Beyond confirming the presence of the disease, the test also helps determine the stage of its progression. This may fundamentally change how physicians manage Alzheimer’s care.
The test was developed by experts at Washington University School of Medicine in St. Louis and Lund University in Sweden. Their studies indicate that a particular blood protein, MTBR-tau243, can be used to monitor the extent of dangerous tau accumulation in the brain.
The tangles of tau protein are some of the hallmark characteristics of Alzheimer’s and are directly proportional to the intensity of the symptoms.
This new technique is considerably more convenient than brain scans since it is non-invasive, and does not require expensive procedures that are difficult to access.
Tracking Alzheimer’s with a blood test
Right now, doctors can use several blood tests to help detect Alzheimer’s. Some of the tests that are already in use are based on earlier discoveries at Washington University.
These tests look for early warning signs but don’t reveal how much the disease has progressed. That’s a crucial gap. Alzheimer’s treatments are most helpful in the early stages, before too much damage has been done.
Having a way to tell whether someone is in an early or late phase of the disease would help doctors decide which treatment would work best. It could also clarify whether a person’s memory or thinking issues are actually caused by Alzheimer’s or something else.
“This blood test clearly identifies Alzheimer’s tau tangles, which is our best biomarker measure of Alzheimer’s symptoms and dementia,” said co-senior author Dr. Randall J. Bateman.
“In clinical practice right now, we don’t have easy or accessible measures of Alzheimer’s tangles and dementia, and so a tangle blood test like this can provide a much better indication if the symptoms are due to Alzheimer’s and may also help doctors decide which treatments are best for their patients.”
A reliable way to monitor the disease
Alzheimer’s typically starts with a buildup of amyloid protein in the brain. Tau tangles develop later and mark the point when symptoms begin to show.
The best way to see these changes has been through PET scans, which can track amyloid and tau deposits. But these scans are expensive, time-consuming, and often only available in large hospitals or research centers. That’s why scientists have been working on blood-based alternatives.
The team had already developed blood tests that measure amyloid plaque buildup. Earlier research showed that levels of MTBR-tau243 in spinal fluid could match up with brain tau levels.
In this new study, the researchers demonstrated that they could get the same results using blood samples. A blood draw is much easier and more accessible than a spinal tap.
Testing the new approach
To validate the test, the researchers used data from two groups of people. One group came from a research center at Washington University and included 108 volunteers. The other group included 55 people from a Swedish study known as BioFINDER-2.
Next, the experts checked their findings with data from 739 additional people in the BioFINDER-2 group.
These participants represented a range of Alzheimer’s stages – from people who had no symptoms but had amyloid in their brains, to those with mild cognitive issues, to people with full dementia.
The study also included individuals with memory or thinking problems due to other conditions, and some who were cognitively healthy.
Alzheimer’s progression revealed in blood
The results were promising. MTBR-tau243 levels in the blood matched the amount of tau tangles in the brain with 92% accuracy.
In healthy people and those in the earliest stage of the disease, the levels were normal. But in people showing symptoms, the protein levels were clearly elevated – and much higher in those with advanced disease.
This difference made it easy to tell who was in an early or late stage of Alzheimer’s. It also helped distinguish Alzheimer’s dementia from other kinds of cognitive problems.
That kind of clarity could make a huge difference in choosing the right treatment path.
The new test uses technology licensed by Washington University to C2N Diagnostics, which previously developed similar blood tests for amyloid plaques. The earlier tests were designed to detect another tau protein called p-tau217.
“I believe we will use blood-based p-tau217 to determine whether an individual has Alzheimer’s disease, but MTBR-tau243 will be a highly valuable complement in both clinical settings and research trials,” said Oskar Hansson, a professor of neurology at Lund University.
“When both of these biomarkers are positive, the likelihood that Alzheimer’s is the underlying cause of a person’s cognitive symptoms increases significantly, compared to when only p-tau217 is abnormal. This distinction is crucial for selecting the most appropriate treatment for each patient.”
Looking ahead to better treatments
Currently, there are two FDA-approved drugs that target amyloid in the brain to slow Alzheimer’s. But more treatments are being tested – including ones that aim at tau protein and other disease mechanisms.
As these therapies become available, doctors will need reliable ways to match the right treatment to each stage of the disease. Blood tests could be the key to this shift toward personalized Alzheimer’s care.
“We’re about to enter the era of personalized medicine for Alzheimer’s disease,” said Kanta Horie, a research associate professor of neurology at WashU Medicine.
“For early stages with low tau tangles, anti-amyloid therapies could be more efficacious than in late stages. But after the onset of dementia with high tau tangles, anti-tau therapy or one of the many other experimental approaches may be more effective.”
“Once we have a clinically available blood test for staging, plus treatments that work at different stages of the disease, doctors will be able to optimize their treatment plans for the specific needs of each patient.”
The full study was published in the journal Nature Medicine.
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