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Can Vaccinations Save Your Brain?

There’s growing evidence that getting your shots can lower dementia risk

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As autumn comes around, so do the placards and public service announcements alerting us to get our flu shots, update our COVID-19 vaccines and generally get on top of the inoculations we need as we get older. 

But after three years of culture wars, dogmatic dogfights and scientific stops and starts, the idea of getting that next shot seems unusually fraught — especially when anti-vaccine celebrities are in the thick of today’s political debates.

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New research has provided yet one more reason why staying on top of your vaccinations makes sense: They might decrease the risk of age-related cognitive decline.

“Vaccination is the right thing to do to protect yourself from flu and other infections,” says Paul E. Schulz, M.D., professor of neurology and director of the Neurocognitive Disorders Center at the McGovern Medical School at UTHealth Houston. “Now there is also the potential fringe benefit of vaccination, which is reducing the risk of Alzheimer’s.”

In recent years, studies have found that those who get vaccinated for the flu and other infectious diseases appear less likely than their unvaccinated counterparts to get dementia — although it’s unclear what happens in the brain to cause this. One theory some experts have is that infection plays a role in developing Alzheimer’s disease and that vaccinations may help stave off these infections.

Others, like Schulz, say it’s possible that vaccination may reduce an immune system function that attacks amyloid plaque (a protein found in abnormally high levels in the brains of Alzheimer’s patients) as an invader, causing chronic brain inflammation and the death of nearby cells.

“The problem in Alzheimer’s is that the immune system keeps trying to get rid of the plaque, and it can’t,” Schulz explains. “The plaque sits there for 10 years, and the immune system keeps throwing poisons at it all that time and is killing brain cells in the process.”

It’s also possible that vaccines may enhance the ability of the immune system to remove amyloid plaques. Schulz was the senior author of a recent study that found a statistically significant difference in the incidence of Alzheimer’s after following two groups — one vaccinated against the flu, the other unvaccinated — for up to eight years.

The groups, of 935,887 each, were obtained from a national patient database. To ensure a valid comparison, both groups shared many of the same characteristics and risk factors, including age, gender and conditions such as hypertension, Schulz says — except one group was vaccinated and the other was not.


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He and his colleagues found that patients who received at least one flu vaccine during the follow-up period of four years were 40 percent less likely to develop Alzheimer’s compared with those who did not get the vaccine. Additional analysis found that those who received an annual flu shot had the lowest rate of the disease.

“The more vaccinations you got, the better,” Schulz says.

His team has been studying the effects of vaccines for other infectious diseases, including shingles, pneumococcal pneumonia and the combination of tetanus, diphtheria and pertussis (whooping cough), known as Tdap, with similar findings, he says.

Another recent study, still to be peer-reviewed, concluded that vaccination with Zostavax (the early shingles vaccine) among a quite senior population in Wales averted an estimated 1 in 5 new dementia diagnoses during a seven-year period, according to Pascal Geldsetzer, M.D., assistant professor of medicine at Stanford University, who conducted the research.

“The exact size of the preventive effect of shingles vaccination for dementia is hard to pinpoint in such an analysis, but our study suggests that the effect is substantial,” Geldsetzer says. “We believe that our analysis provides compelling evidence that shingles vaccination prevents or delays dementia in this older age group.”

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Virologist Robert T. Schooley, M.D., an infectious disease specialist at the University of California, San Diego — who has not been involved in any of the studies — says it is “certainly plausible” that reducing the frequency and severity of influenza through vaccination can quell immune activation over time.

“Other conditions associated with chronic or recurrent uncontrolled systemic inflammation such as chronic HIV infection can also be associated with accelerated cognitive decline, and this mechanism might well account for the findings,” he says.

Though experts say the growing evidence is promising, some suggest caution when interpreting the results.

“No matter how hard you try to control that the two groups are comparable, there is the residual sense that folks who choose to get vaccinated are different in unmeasurable ways from those who do not get vaccinated,” says William Schaffner, M.D., professor of preventive medicine at Vanderbilt University School of Medicine. These “unmeasured differences” could have an impact on the incidence of dementia and distort the possible influence of the vaccines, he says.

Regardless, Schaffner adds, “this is not an issue that ought to figure notably in one’s decision whether to receive vaccines. The data are clear that vaccines help prevent influenza, COVID, pneumococcal disease, shingles and so forth. As I am wont to observe: Disease bad; vaccines good.”

Schooley agrees, saying, “One thing is for certain: Whether or not this observation is real, staying up to date with vaccinations for influenza and other infectious diseases as we age is a good idea.”

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