A new study has found that problems in the immune system might be a key factor in the start and worsening of Alzheimer’s disease. The research was done by scientists at Temple University in the U.S. and published on April 15, 2025, in the Journal of Alzheimer’s Disease.
Alzheimer’s disease is the most common form of dementia. It slowly damages memory and thinking skills, eventually affecting a person’s ability to do everyday activities. For many years, scientists believed that the main causes of Alzheimer’s were two harmful proteins—amyloid-beta and tau.
These proteins build up in the brain, forming plaques and tangles that interfere with brain function. While these proteins are still considered important in Alzheimer’s, more and more research now shows that the immune system might also play a major role.
In this study, researchers examined brain tissue from animals that were used to model Alzheimer’s disease. They focused on how the immune system acts inside the brain. What they found suggests that the body’s immune system may become confused and start to act in a harmful way—even though it is supposed to protect us.
The research team used a method called RNA sequencing, which lets scientists look at how genes are turned on or off in brain cells. They discovered patterns that point to immune system changes connected to Alzheimer’s. Specifically, they found signs of something called “trained immunity,” which is a type of long-lasting memory in the immune system.
Normally, this memory helps the body respond more quickly to germs it has seen before. But in this case, the immune memory seems to be going in the wrong direction—overreacting in a way that might damage the brain.
They also found signs that certain brain cells may change into different types, a process called “cellular reprogramming” or “cell trans-differentiation.” This can happen when cells are under stress or attacked by inflammation, and it might be another way Alzheimer’s gets worse over time.
Dr. Domenico Praticò, one of the lead scientists in the study, explained that these findings show a new side of Alzheimer’s disease that hasn’t received much attention until now. He is the director of the Alzheimer’s Center at Temple and has spent years studying how the disease develops.
He said this research highlights how the immune system can become too active, starting a harmful chain reaction. First, the immune cells in the brain react too strongly to certain “trigger” molecules—such as the amyloid-beta and tau proteins.
This strong response causes inflammation, which doesn’t go away. Instead, it becomes chronic, meaning it continues for a long time. This long-term inflammation damages brain cells and may cause them to behave in strange ways, speeding up the development of Alzheimer’s.
At the same time, the immune system “remembers” this reaction and stays in a state of high alert. But instead of helping, this trained immune response keeps making things worse by promoting even more inflammation and changes in the brain. In other words, the immune system might accidentally help drive the disease forward.
This study is important because it adds to our understanding of what causes Alzheimer’s. While amyloid and tau proteins are still key pieces of the puzzle, this new research shows that the immune system—and especially inflammation—may play just as big a role. If scientists can find ways to calm down this overactive immune response, they may be able to slow or stop the disease.
In summary, the research suggests that Alzheimer’s disease may partly act like an autoimmune condition, where the body’s own immune system starts to attack itself.
By understanding how the immune system behaves in Alzheimer’s, scientists can begin to look for new kinds of treatments—ones that don’t just target protein build-up, but also aim to reduce harmful inflammation and restore balance to the brain’s immune activity. This could lead to better outcomes for people living with Alzheimer’s in the future.
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.
The research findings can be found in Journal of Alzheimer’s Disease.
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