UT Health researchers identify possible link between flu vaccine, reduced rate of Alzheimer’s

Here's what we know

Alzheimer’s disease affects more than six million people living in the U.S., with the number of affected individuals growing due to the nation’s aging population.

UT Health Houston scientists are researching how people who received at least one influenza vaccine were 40% less likely than their non-vaccinated peers to develop Alzheimer’s disease.

How could that be?

According to UT Health Houston, during four-year follow-up appointments, fewer flu-vaccinated patients were found to have developed Alzheimer’s disease than non-vaccinated patients who developed the disease.

However, the underlying mechanisms behind why this happens requires further study.

How did they figure this out?

The author of the study, Dr. Paul Shulz, said researchers were able to access a broad database of patient files now that healthcare records are digitized, and they can see the people who get vaccinated against the flu, which there was a significant decrease in later developing Alzheimer’s disease.

The team compared groups of people with the same risk factors and similar access to healthcare. They found the vaccine may prevent plaque from forming and contributing to cognitive decline.

“In the one group, the unvaccinated, we found that about 80,000 people developed Alzheimer’s out of 950,000 over the next eight years,” Dr. Shulz said. “Then in the vaccinated group, only 47,000. So, that was a difference of 33,000 people.”

If the vaccine contains the virus, how could the vaccine be better than the infection?

Dr. Shulz said he started the study because he was hesitant about recommending the flu vaccine to Alzheimer’s patients before, or at least wondered if the vaccine would contribute to cognitive decline in the same way a viral infection progresses the disease.

“I’ve always wondered, ‘Hey when we do that we’re basically giving people dead virus and bacteria... How is that different from the real thing and are we making our Alzheimer’s patients worse?’”

He said now he has confidence that the immune system recognizes the vaccine differently than the viral infection. He does not believe the vaccine will hurt Alzheimer’s patients and may provide protection to people who don’t have the disease.

Shulz said the risk of Alzheimer’s was lower among people who had more annual vaccines than among those who had fewer vaccines in the eight-year window. This may show the flu vaccine has a cumulative benefit for those who get it annually.

The research is not final.

Shulz said, “Clearly, we have more to learn about how the immune system worsens or improves outcomes in this disease.”