Flu and pneumonia shots may lower risk for Alzheimer’s, studies find

It turns out that flu and pneumonia shots may be good for more than what their names suggest.

Not only does getting a shot reduce your chances of coming down with a nasty infection, but getting vaccinated may also reduce your risk of developing Alzheimer’s disease in the future, according to two separate abstracts presented at the Alzheimer’s Association International Conference on Monday.

“This is an encouraging finding that builds upon prior evidence that vaccination against common infections diseases — such as the flu — is associated with a reduced risk for Alzheimer’s and a delay in disease onset,” said neurologist Dr. Richard Isaacson, founder of the Alzheimer’s Prevention Clinic at NewYork-Presbyterian and Weill Cornell Medical Center, who was not involved in the study.

“Regular use of the flu vaccine, especially starting at an early age, may help prevent viral infections that could cause cascading effects on the immune system and inflammatory pathways. These viral infections may trigger Alzheimers related cognitive decline,” Isaacson said.

But experts say more studies are needed to pin down the relationship between getting those vaccines and the reduced risk.

There is no cure for Alzheimer’s disease (AD) yet, but research shows paying attention to certain key lifestyle factors — including getting proper sleep, nutrition and exercise — may influence a person’s individual risk. Getting vaccinated may fall into that category.

If getting vaccinated for flu or pneumonia, just on its own, can reduce the risk of Alzheimer’s, then these are important messages to get out to the public, Alzheimer’s Association chief science officer Maria Carrillo told CNN.

“We do need more research to understand what that connection is,” said Carrillo, who oversees research initiatives for the association.

“Is it direct, the vaccine to disease? Or is it protective, as a part of the risk reduction strategies that we have, like lower your BMI (body mass index), watch your sugar intake, keep an eye on your cholesterol and high blood pressure, exercise, get vaccinated,” she added. “It’s one of those sort of health tips that we need to make sure that our public knows about.”

Influenza vaccine and AD

The first study, presented by Albert Amran, a fourth-year medical student with McGovern Medical School at The University of Texas Health Science Center at Houston, examined a large American health record data set of more than 9,000 patients over the age of 60.

The researchers found having one flu vaccination was associated with a 17% reduction in Alzheimer’s incidence. Those who were vaccinated more than once over the years saw an additional 13% reduction in incidence.

The protective association appeared to be strongest for those who received their first vaccine at a younger age, for example at age 60 versus 70.

“There has been a concern in the medical community that many sources of inflammation, such as urinary tract infections, worsen the course of patients with Alzheimer’s disease,” Amran told CNN. “Hence, we have been worried that vaccinations, a form of inflammation, could also worsen the course of AD.”

At the same time, Amran said, doctors recommend flu vaccinations for people with Alzheimer’s because the flu is often deadly. According to the US Centers for Disease Control and Prevention, flu has killed between 12,000 and 61,000 people annually in the United States since 2010.

Therefore the results of the study, although unexpected, were welcome, Amran said.

“We were very surprised, because of the concern noted above about the potential to increase AD, when our statistical colleagues told us that the flu vaccination was one of the ‘medications’ that is so strongly associated with a lower Alzheimer’s incidence,” he said.

More research is needed to explore the biological mechanism for this effect ​—​ why and how it works in the body, Amran said. One of his team’s theories is that the effect of vaccination may be related to keeping the immune system “in shape” as people get older. Another theory is that prevention of flu itself may be relevant.

Pneumonia vaccine and AD

The second abstract examined the associations between pneumococcal vaccine, with and without an accompanying flu shot, and the risk of Alzheimer’s. The study analyzed over 5,000 people over 65 who were participating in the Cardiovascular Health Study, a long-term government funded look at risk factors for cardiovascular disease.

Some of the participants had a known genetic risk factor for Alzheimer’s: the rs2075650 G allele in the TOMM40 gene, which has also been linked to a higher risk for lifetime depression.

The researchers found that getting a pneumococcal vaccine between the ages of 65-75 reduced risk of developing Alzheimer’s by 25 to 30% after adjusting for sex, race, birth cohort, education, smoking and genetic risk factors.

However, the largest reduction in the risk of Alzheimer’s — up to 40% — was seen among people vaccinated against pneumonia who didn’t have the risk gene.