Alzheimer’s disease is a serious brain condition that slowly affects memory, thinking, and daily life. Scientists have long known that two key proteins are involved in this disease: amyloid-beta and tau.
Amyloid builds up outside brain cells, while tau normally helps support the structure inside nerve cells. However, in Alzheimer’s disease, tau changes in a harmful way and forms tangles inside the cells, damaging them over time.
One special form of tau, called p-tau217, can now be measured in the blood. This has opened the door to new and less invasive ways to detect Alzheimer’s disease. In fact, researchers have found that changes linked to Alzheimer’s can appear in the blood up to 20 years before symptoms begin.
While this early detection is impressive, it also creates a challenge. If a test detects signs too early, it may not be clear whether those changes are actually causing a person’s current symptoms.
A new study led by Niklas Mattsson-Carlgren from Lund University and Skåne University Hospital explores how to make these blood tests more useful in real medical care.
The findings were published in The Lancet Neurology and are based on data from 572 people who visited clinics due to memory or thinking problems. These participants were part of the large BioFinder2 study.
The researchers focused on measuring levels of p-tau217 in the blood. They found that among 350 people with high levels of this protein, 341 of them, or 97 percent, also had amyloid in their brains. This confirms that p-tau217 is a very strong signal that Alzheimer’s-related changes are happening in the brain.
However, having these changes does not always mean that a person has developed Alzheimer’s disease. In the study, only 199 of the 350 people with high p-tau217 levels actually met the criteria for Alzheimer’s disease.
This means that many people had early signs in their brain but had not yet reached the stage where the disease caused clear symptoms. These cases are called false positives, and they can make diagnosis more difficult.
To improve accuracy, the researchers looked at another blood marker called eMTBR-tau243. When they combined this marker with p-tau217, the results became much clearer.
Among those who tested positive for p-tau217, 194 people also had high levels of eMTBR-tau243. Using both markers together allowed researchers to identify people with established Alzheimer’s disease with about 80 percent accuracy.
At the same time, the number of false-positive results dropped significantly, from 43 percent to just 16 percent. This means the combined test is much better at identifying people who truly have Alzheimer’s disease, rather than those who only show early changes.
The researchers also confirmed their findings in a separate group of participants in the United States, which strengthens the reliability of the results. They found that people with both markers not only had a higher chance of having Alzheimer’s disease, but they also experienced faster memory decline and showed more buildup of tau protein in the brain over time.
This study highlights an important idea: timing matters when it comes to testing for Alzheimer’s disease. Detecting changes too early may lead to confusion, while detecting them at the right stage can help doctors make better decisions about diagnosis and treatment.
Although the results are promising, the test still requires advanced laboratory methods, such as mass spectrometry, which are not widely available in everyday clinics. The next step for researchers is to simplify the test so that it can be used more easily in primary care settings.
This research is the result of collaboration between scientists at Lund University and Washington University. It represents an important step toward more accurate and practical blood tests for Alzheimer’s disease.
In the future, combining multiple blood markers may help doctors identify not only whether a person has Alzheimer’s disease, but also how advanced it is. This could lead to earlier and more precise treatment, giving patients and their families more time to plan and manage the condition.
If you care about Alzheimer’s, please read studies about Vitamin D deficiency linked to Alzheimer’s, vascular dementia, and Oral cannabis extract may help reduce Alzheimer’s symptoms.
For more information about brain health, please see recent studies about Vitamin B9 deficiency linked to higher dementia risk, and results showing flavonoid-rich foods could improve survival in Parkinson’s disease.
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