A simple blood draw is moving closer to providing information about Alzheimer’s disease that once required expensive brain scans.
Researchers have identified a group of seven blood proteins that may help reveal whether the disease has reached a more advanced biological stage. The approach could eventually make it easier to select patients for treatment and Alzheimer’s research.
Alzheimer’s is not a disease that suddenly begins when someone starts forgetting names or appointments.
Changes can develop silently inside the brain for years before dementia appears. This long hidden period has made early diagnosis one of the biggest challenges in Alzheimer’s care.
One early change is the buildup of a protein called amyloid. It forms sticky plaques between brain cells. Later, another protein called tau can become abnormal and form tangles inside nerve cells, disrupting their ability to work and survive.
The location and amount of tau are particularly important because tau buildup is closely connected with the progression of Alzheimer’s and loss of brain function. A person may have evidence of amyloid but still have relatively limited tau changes. Another person may already have widespread tau and be much further along in the biological course of the disease.
Until recently, doctors had relatively few ways to see these changes while a person was alive. Cerebrospinal fluid collected through a lumbar puncture can reveal Alzheimer’s-related proteins, while PET imaging can show amyloid or tau deposits in the brain. Both methods have transformed research and diagnosis, but neither is ideal for screening very large numbers of people.
PET scanning is costly and requires specialized equipment and radioactive tracers. Lumbar punctures are routinely performed in medicine but are more involved than ordinary blood collection. These practical barriers have encouraged scientists to develop blood tests that could bring biological Alzheimer’s testing to many more clinics.
P-tau217 has emerged as one of the leading blood markers. It measures a particular form of tau that rises in association with Alzheimer’s changes in the brain. Research has shown that it can be highly useful for identifying people who are likely to have Alzheimer’s-related amyloid pathology.
Yet knowing that Alzheimer’s biology is present is only part of the problem. Doctors may also need to know whether tau changes are still limited or have become advanced. That information can influence how researchers classify patients and may become increasingly relevant when choosing among treatments.
A team at the University of Gothenburg and collaborating research centers investigated whether a broader look at blood proteins could provide this missing information. They used data from two separate international groups, an important feature because a result seen in one group may not always work in another. Their testing platform measured more than 120 proteins in each blood sample.
Many of these proteins were connected with inflammation or the health and activity of nerve cells. Instead of selecting the best combination by hand, the scientists used machine-learning methods to search for patterns associated with advanced tau buildup. The computer models could evaluate many possible relationships between proteins at the same time.
Seven proteins emerged as a useful combination, with p-tau217 remaining an important part of the panel. Adding the other proteins significantly improved the ability to identify advanced tau pathology in people who already had increased amyloid. In other words, the additional blood signals appeared to tell researchers something about disease stage that p-tau217 could not provide by itself.
The result is important because tau PET currently offers a detailed way to assess the spread of tau in the brain. A reliable blood alternative could make biological staging cheaper and easier to use. It might also help doctors decide which patients truly need a PET scan rather than using the scan as the first step.
This kind of screening could become especially useful as Alzheimer’s treatment changes. New medicines aimed at the underlying biology of the disease have increased the need for accurate testing before treatment begins. A person’s biological disease stage may affect whether a therapy is appropriate and how doctors weigh its potential benefits and risks.
Clinical trials could benefit as well. Testing a new Alzheimer’s treatment often requires researchers to find people who meet narrow biological criteria. Screening thousands of potential volunteers with PET scans is difficult and expensive, while an initial blood test could help identify the smaller group most likely to qualify.
The study was published in JAMA Neurology. Guglielmo Di Molfetta, a doctoral student in neurochemistry at the University of Gothenburg, and colleagues reported that the seven-protein profile improved the ability of blood testing to identify people with a later-stage Alzheimer’s pattern. The researchers suggest that such multiprotein testing could become an alternative screening tool for some uses now served by tau PET.
There are several reasons not to overstate the finding. The study shows that combining proteins can improve classification, but a research model is not automatically ready for use in ordinary clinics. It must be tested in larger populations, including people with other neurological diseases and medical conditions that might change protein levels in the blood.
Machine learning also depends heavily on the quality and diversity of the information used to train it. If a model is developed mainly from particular populations, it may not perform equally well in everyone. Independent studies will be needed to establish reliable cutoffs and determine how the test performs in real-world patients whose diagnoses are uncertain.
The study also does not establish that the seven-protein test can precisely predict how quickly a particular person will develop memory problems or dementia. Biological stage and future clinical decline are related, but they are not identical. Age, other brain diseases, general health, and individual differences can all influence how symptoms develop.
Even with these limits, the research represents an important shift in Alzheimer’s testing. Rather than asking one blood protein to answer every question, scientists can combine several signals to build a more detailed picture of the disease.
If future studies confirm the results, a tube of blood may one day help doctors not only detect Alzheimer’s changes but also estimate how far those changes have progressed.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
Source: University of Gothenburg.
