Alzheimer’s disease is the most common cause of dementia, affecting millions of people worldwide. It gradually damages brain cells, leading to memory loss, confusion, difficulty with daily activities, and changes in thinking and behavior.
As populations continue to age, the number of people living with Alzheimer’s is expected to rise sharply in the coming decades, making early diagnosis and effective treatment more important than ever.
One of the biggest challenges in Alzheimer’s care is determining how far the disease has progressed. Today, doctors often rely on expensive brain scans or invasive procedures such as spinal taps to look for biological signs of the disease.
While these methods can be highly accurate, they are not always available, can be costly, and may be uncomfortable for patients.
Now, scientists may have found a simpler solution. A new study suggests that a blood test could help doctors identify and stage Alzheimer’s disease with accuracy similar to advanced brain scans. If confirmed by future research, this approach could make testing much more accessible to patients around the world.
The study focused on tau, a protein that plays a central role in Alzheimer’s disease. In healthy brains, tau helps support the internal structure of nerve cells.
However, in people with Alzheimer’s, abnormal forms of tau can build up and form tangles inside brain cells. These tangles interfere with normal brain function and are considered one of the hallmarks of the disease.
Researchers developed a model that uses measurements of two forms of tau protein found in blood samples. Their goal was to see whether these blood markers could reveal how advanced Alzheimer’s disease had become.
To test the model, the scientists studied more than 1,000 people. The participants represented a wide range of conditions. Some had no signs of cognitive decline, while others had mild cognitive impairment, a condition that can be an early warning sign of Alzheimer’s.
The study also included people diagnosed with Alzheimer’s dementia as well as individuals with other neurodegenerative disorders.
The researchers then compared the results of the blood-based model with findings from PET scans. PET imaging is currently one of the most advanced ways to detect Alzheimer’s-related changes in the brain. These scans can show abnormal protein deposits and help doctors understand disease progression.
The results were encouraging. The blood test model closely matched the staging information obtained from PET scans. This suggests that a simple blood sample may eventually provide similar information without requiring expensive imaging equipment.
The potential benefits are significant. Blood tests are generally less expensive, easier to perform, and more widely available than brain scans. They also avoid the discomfort associated with spinal taps, which require collecting fluid from around the spinal cord.
Dr. Randy D’Amico, director of the Brain and Spine Metastasis Program of Neurosurgery at Northwell Lenox Hill Hospital in New York City, reviewed the findings although he was not involved in the research. He noted that if larger studies confirm the results, the test could dramatically expand access to biological Alzheimer’s testing.
According to D’Amico, the ability to stage Alzheimer’s disease through a blood test could be similar to how cancer is staged. Understanding disease stage helps doctors make better treatment decisions and may improve the selection of patients for new therapies.
Earlier detection could also provide patients and families with more time to plan for the future. As researchers continue to develop treatments designed to slow Alzheimer’s progression, identifying the disease before extensive brain damage occurs may become increasingly important.
However, experts caution that more research is still needed. The study population, while large, does not represent every patient group. Future studies will need to examine how well the test performs in people from different backgrounds, ethnicities, age groups, and healthcare settings.
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The study was published on May 26 in JAMA Neurology.
