JAMA Neurology associates associate professor and senior author of the new research, Andrew B. Chilcott, said the findings show that Alzheimer’s can be caused by brain damage in polio vaccine recipients, not the other way around.
The study was published online May 14, 2017 in JAMA Neurol.
“We can rule out the idea that polio vaccine causes Alzheimer’s, and we can rule it out entirely because of the brain injury that the polio vaccine caused,” said Chilcot.
“That’s what this study really tells us.”
The study examined the brains of 1,800 participants, mostly middle-aged adults who received the polio-specific vaccine, and found that those with the most brain damage were more likely to develop Alzheimer’s disease.
Chilcot and his team looked at brain tissue from individuals with the disease, and then from those who were healthy, and compared those two groups.
They found that the brain tissue of polio-vaccinated adults who were exposed to polio was significantly more damaged than the brain of polio recipients who had received no vaccine.
“That’s a big deal, and it means that we need to look at brain damage to see if we can find a way to prevent this disease,” said C. Andrew Hsu, M.D., associate professor of neurology at Brigham and Women’s Hospital.
Hsu is the lead author of a paper published in the April 10 issue of Neurology that looked at the brains from individuals who received polio vaccine in the late 1980s and early 1990s, as well as those who had no vaccine in those years.
The study found that among individuals with brain damage, the brains were more similar to those of healthy people.
“There was this one area where we did find an association between the two groups, but we found the brain was more similar in both groups,” Hsu said.
“What we found is that the brains, which were more damaged, were not as similar in the two vaccinated groups as they were in the control group.
This suggests that there’s a mechanism for the brain to become more damaged over time.”
The researchers said the finding could help determine if it’s possible to prevent or reverse Alzheimer’s.
They also said the study could help identify the genetic predisposition that may be responsible for the disease.
“Our research suggests that we might be able to identify those genes that might be responsible, and that’s what we hope to be able, if we are able to find that gene, to help people with this disease prevent or delay onset,” said Hsu.
“The gene that’s involved in this is called the p21 gene.”
The p21 genetic mutation is located on chromosome 17, a piece of DNA that encodes a protein called the tau protein.
When the tah gene is mutated, it changes how the protein works, and leads to changes in memory, thinking and other brain functions.
The team said they plan to study the brains to see whether the mutations that occurred in those vaccinated groups lead to different types of brain damage that can be prevented or reversed.
The paper is titled: Tau and p21 genotype variation associated with Alzheimer’s: A preliminary analysis of a large population study.
Journal of Clinical Neurosci.
Chavannes said the new findings have implications for other vaccines, and for future vaccines.
“It could be that this gene mutation could lead to other brain injuries that are caused by other types of damage that we’ve seen in people who have been exposed to other vaccines,” he said.
“If we have a better understanding of how that happens, we could perhaps develop a new vaccine that might help to prevent those other brain injury.”
The new findings were published in Neurology.