As people age, changes slowly build up inside their cells. Every day, our cells divide, repair damage, and respond to the environment around them.
During these processes, small mistakes can appear in DNA. These mistakes, known as mutations, become more common over time.
Most of them are harmless, but some can affect how cells behave. Scientists have long known that certain mutations can lead to cancer. Now, a major new study suggests that some of these same mutations may also play a role in Alzheimer’s disease.
The research, published in the journal Cell, was led by Dr. Christopher Walsh and colleagues at Boston Children’s Hospital.
The team made a surprising discovery while studying microglia, special immune cells that live in the brain.
These cells act as the brain’s maintenance crew. They remove waste, clean up damaged cells, and help protect the brain from infections and injury.
Alzheimer’s disease is the most common cause of dementia. It gradually damages memory, thinking abilities, and daily functioning.
Around the world, millions of people are affected by the condition. Scientists have spent decades studying the disease, but many questions remain unanswered.
Most research has focused on protein buildups in the brain, such as amyloid plaques and tau tangles. This new study points to another possible factor.
The researchers examined brain tissue from 190 people who had Alzheimer’s disease and compared it with brain samples from 121 people without the condition.
They looked closely at 149 genes known to drive cancer. To their surprise, they found that brain immune cells in people with Alzheimer’s carried more mutations than those in healthy brains.
Even more surprising was where these mutations appeared. Many were found repeatedly in the same small group of genes that are commonly involved in blood cancers such as leukemia and lymphoma.
This suggested that the mutations were not random. Instead, they appeared to be giving certain cells an advantage that allowed them to multiply more successfully.
The discovery led researchers to ask an important question. If these mutations are usually linked to blood cancers, could similar mutated cells also be present in the blood of people with Alzheimer’s disease?
The scientists did not expect to find much. However, when they tested blood samples, they found the same cancer-related mutations.
This finding challenged a long-standing assumption about the brain. Scientists once believed that microglia remained isolated inside the brain and did not mix with immune cells from the bloodstream.
The new evidence suggests that under certain conditions, immune cells carrying cancer-related mutations may enter the brain.
The researchers believe that aging or damage may weaken the blood-brain barrier, a protective layer that normally keeps harmful substances and cells out of the brain. Once immune cells from the blood enter the brain, they may take on roles similar to microglia.
At the same time, Alzheimer’s disease creates an environment filled with inflammation and protein buildup. This may encourage certain mutated immune cells to expand in number. Because these cells carry mutations that help them grow and survive, they may gradually become more common inside the brain.
According to the researchers, these altered cells may behave differently from healthy microglia. Instead of simply cleaning up damage, they may create a more harmful inflammatory environment. Over time, this could contribute to the death of nearby brain cells and worsen the progression of Alzheimer’s disease.
The discovery could have important practical benefits. One possibility is the development of blood tests that identify people who carry these mutations before symptoms become severe. Because obtaining brain tissue from living patients is extremely difficult, blood-based testing would be much easier and safer.
The researchers also suggest that treatments developed for certain cancers may eventually help some people with Alzheimer’s disease. Since the same mutations appear to be involved, drugs designed to target those abnormal cells might have potential in future Alzheimer’s treatments.
The study has important strengths, including a large number of brain samples and advanced genetic analysis. However, it does not prove that the mutations directly cause Alzheimer’s disease. More research is needed to understand exactly how these cells contribute to the condition and whether targeting them can slow disease progression.
Overall, the findings represent a major shift in how scientists think about Alzheimer’s disease. Instead of viewing it only as a disorder caused by protein buildup, researchers may now need to consider the role of mutated immune cells as well. If future studies confirm these results, they could open entirely new directions for diagnosis and treatment.
The research highlights how discoveries in one area of medicine, such as cancer biology, can unexpectedly provide insights into another major disease affecting millions of people worldwide.
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.
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Source: Boston Children’s Hospital.
