Flu shots might lower risk of Alzheimer’s, related dementias

  • Comments
  • Print

There are many good reasons to get a flu shot this fall, but here’s one that might surprise you: It could protect your brain.

Recent research suggests that regular vaccinations against influenza and other infectious diseases such as shingles, pneumococcal pneumonia, and tetanus, diphtheria and pertussis (whooping cough) may reduce the risk of developing Alzheimer’s disease and related dementias.

“Vaccines are the great public health success story of our generation,” said Paul E. Schulz, professor of neurology and director of the Neurocognitive Disorders Center at the McGovern Medical School at UTHealth Houston, who led several of the studies. “They keep you safe from any number of infections, many of which can be life-threatening. And now it appears there is another tremendous benefit, this one against a disease that is among the most feared.”

What the research says

A number of studies have found that people receiving vaccinations for flu and several other infectious diseases appear less likely than the unvaccinated to develop dementia, although scientists aren’t sure why. Some believe that infectious agents play a role in the development of Alzheimer’s disease and that vaccinations help by preventing or reducing the likelihood of getting these infections.

Alternatively, Schulz speculates that vaccines may curb an immune system reaction to amyloid plaque, a naturally occurring protein found in abnormally high levels in Alzheimer’s. The immune system sees plaque as a foreign invader and attacks it, causing chronic brain inflammation and the death of nearby neurons, which contribute to dementia, he said.

In quelling the immune response to amyloid, vaccines may save brain cells that the body’s immune system might otherwise kill, he said. It’s also possible that vaccines strengthen the immune system’s ability to get rid of plaque. “Fewer plaques lead to less inflammation and less brain cell loss,” Schulz said, adding: “We aren’t sure yet exactly what the mechanism is, but something is going on with the brain and the immune system that seems to make a big difference.”

Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children’s Hospital Center for Vaccine Development, said the studies “suggest long-term benefits from immunizations with vaccines that may go beyond the intended direct benefits.”

It is unclear why vaccinations may slow or prevent dementia, Hotez said. “In some cases, they may prevent viruses from causing direct neurological involvement, especially for neurotropic viruses, or indirectly through brain inflammation that can result from pathogens,” he said. “In other cases, they may stimulate innate immune mechanisms that may be protective against the sequence of events leading to dementia.”

Schulz led a recent study that found a statistically significant difference in the incidence of Alzheimer’s after following two groups – one vaccinated against flu, the other unvaccinated – for up to eight years.

In the flu study, the researchers took participants from a national patient database, two groups of 935,887 each, one group vaccinated, the other not. To avoid the potential influence of various factors that could affect the results, the scientists ensured that each group shared many of the same characteristics, such as age, gender, how frequently they went to the doctor, and certain medical conditions, such as high blood pressure and elevated cholesterol.

Schulz and his colleagues found that an annual flu vaccination for three consecutive years reduced the dementia risk 20 percent over the next four to eight years, while six shots doubled it to a 40-percent reduction.

There were 47,889 cases of dementia in the vaccinated group, compared with 79,630 in the unvaccinated participants,  a difference of more than 30,000 cases, Schulz said.

Similar results from other vaccines

In another study, his team found similar results with vaccines for other infectious diseases, including shingles, pneumococcal pneumonia and the combination of tetanus, diphtheria and pertussis (whooping cough), known as Tdap, or with tetanus and diphtheria without the pertussis component.

With the shingles vaccines, for example, (Zostavax, the early shingles vaccine, and Shingrix, the most recent one), the researchers compared 198,847 patients, who were vaccinated to an equal number who were not, Schulz said. Among the vaccinated, 16,106 patients developed Alzheimer’s during the eight-year follow-up, compared with 21,417 of the unvaccinated—or 5,311 fewer patients in the vaccinated group got dementia.

With Tdap and Td vaccines, the researchers compared two groups of 116,400 patients each, one vaccinated, one not. In the vaccinated, 8,370 individuals developed dementia over the eight years, compared with 11,857 in the unvaccinated—3,487 fewer patients among the vaccinated.

With the pneumococcal vaccine, they compared two groups of 260,037 each, one group vaccinated, the other unvaccinated, and recorded 20,583 dementia cases among the vaccinated after eight years, compared with 28,558 unvaccinated people—7,975 fewer patients in the vaccinated group, Schulz said.

In two studies conducted in the United Kingdom, still unpublished and under peer review, researchers at Stanford University found similar results. The first, among an older population in Wales, suggests that vaccination with Zostavax prevented an estimated 1 in 5 new dementia cases during a seven-year period, said Pascal Geldsetzer, assistant professor of medicine in the division of primary care and population health at Stanford University, who led the research.

The second analyzed mortality data for England and Wales and found a 5 percent difference in the probability of dying from dementia, or 1 in 20 deaths averted, during a nine-year follow-up.

For both studies, the scientists established two groups for comparison purposes based on the country’s birth date eligibility requirements. Those who turned 80 just before the vaccine program started were not eligible for the vaccine, and remained ineligible, while those who turned 80 just after the program began received the vaccine free over the course of the following year.

“It is likely that the only difference between the two comparison groups was a tiny difference in age, but a large difference in the probability of getting the shingles vaccine,” Geldsetzer said. “That makes our study fundamentally different in its approach to studies that simply compare people who get vaccinated with those who don’t. We think that our findings from this unique natural randomization strongly suggest a causal relationship.”

Need for more research

Experts said more studies were needed to determine the effects of the vaccine on the brain.

There may be undetectable factors that distinguish the vaccinated from the unvaccinated, despite researchers’ efforts to control for them, such as prior head injuries, genetics or environmental exposures, said William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University.

Regardless, experts agree that people should get their shots. “All this requires further studies, but vaccination, along with good diet, exercise, intellectual and emotional stimulation are key factors for healthy aging,” Hotez said.

No one should suffer from preventable diseases, Schaffner said: “Vaccinations are a critical means of staying well and living a healthy life.”

Please enable JavaScript to view this content.

Editor's note: You can comment on IBJ stories by signing in to your IBJ account. If you have not registered, please sign up for a free account now. Please note our updated comment policy that will govern how comments are moderated.

9 thoughts on “Flu shots might lower risk of Alzheimer’s, related dementias

  1. Apparently only 2-3% of Americans have decided so far to get the COVID boosters. I mean, it’s early in the flu season, so that may change, but such indifference is alarming. I guess this means, if things don’t change soon, up to 95% of Americans will fit the standard of “anti-vaxxers”. Remarkable.

  2. Moderna and Pfizer share prices are also down catastrophically. Is it a coincidence that we’re suddenly getting breakthrough research that vaccines may fend off Alzheimer’s?

    I mean, who is a conspiracy theorist like little old me to doubt the esteemed doctor Peter Hotez, the same one who refuses to debate that anti-vax whackadoodle RFK Junior? Dr. Hotez routinely wears a bow tie, so we know he must be very brainy and very brainy people can never get corrupted by fiduciary influences. He also gets published in “Nature”, an esteemed publication that would never dream of compromising its research for ideologically driven ESG money.

    Maybe Dr. Hotez is worried a tough guy like RFK Jr would engage in fisticuffs. After all, Hotez had to hire private security because followers of Joe Rogan Experience threatened to beat him up for his brave championing of immunology through vaccines and refusal to give an inch to the naysayers. Maybe Joe Rogan himself was going to beat up the good doctor. It wouldn’t be the first time.

    We must remember: after Joe intellectually clobbered Dr. Sanjay Gupta for continuing to belittle him for using ivermectin, Rogan (amped up on horse de-wormer) proceeded to threaten to physically clobber Dr. Gupta. We know Joe Rogan did this because Dr. Gupta said so afterward.

    1. Keep pretending you aren’t 100% political yourself Wesley.

      You just don’t like my politics.

      It’s how brains work when the corruption is at chin level and you’re barely able to keep you head high enough for air. I’m sorry you don’t see it. Eventually, when it hits you in the pocket book (or you get punched in the face), maybe you will.

    2. I’m not pretending anything Lauren. I don’t read articles linking flu shots with a decrease in a horrible disease and think anything political at all. That’s just you and other cult members. And no, not all Republicans are members of a cult.

    3. What does it mean that only 2-3% of people have gotten their COVD vaxxes? If this is truly a “horrible disease”, you’d think those numbers would at least be in the double digits. I mean, you’re the enlightened one here–you know the experts have our best interests at heart and that medicine is based on achieving near perfect consensus. And the doubters are always just a bunch of crackpots. And if those crackpot doctors number in the 10s of thousands, it’s still just a fluke, and they need to be censored for peddling misinformation.

      Mask up this winter. Everyone will know what a good, moral, intelligent person you are. And you’ll be nice and healthy, while little unvaxxed me is almost certainly going to drop dead of COVID.

      Y’all are such fascinating creatures. Someday when I retire, I hope to go out and study you, using the intellectual practices of Margaret Mead. Or Jane Goodall.

    4. JAMA Internal Medicine published a study in July of this year that evaluated over 538K deaths in individuals 25 years and older in FL and OH between March 2020 and December 2021. It found excess mortality was significantly higher (43%) for registered Republican voters than Democratic voters after COVID-19 vaccines were available to all adults, but not before. The differences were concentrated in counties with lower vaccination rates, and primarily noted in voters residing in OH.

      “Future policy decisions should be guided by public health considerations rather than by political ideology,” said the authors of that study, which was selected as the article of the year by the American Journal of Preventive Medicine.

      (No word on whether any of them wore bow ties.)

    5. JAMA. Is that supposed to be a credible journal? I’m sure it probably once was. So was “Nature” and “Scientific American”–but when journals become politically subverted, the politics becomes their priority, not the science. And that describes pretty much all of them. They’re as reliable for science research as “New York Times” is for reporting, or the NIH is for giving neutral medical analysis. Pure garbage.

      You probably ought to tell the naysayers this time around, because, as far as COVID vax is concerned, that includes well over 90% of the population.

      As for vaccines helping dementia, the POTUS you fortified into the White House makes sure we know he gets vaxxed routinely. Lectures the rest of us on it too. hasn’t stopped him from getting COVID multiple times. And as for fending off cognitive impairment, well…

    6. So, are you disputing the work of the researchers from Yale University because it was published in JAMA? Sounds like (yet another) ad hominem attack. Or maybe because it doesn’t support your viewpoint? Facts can be messy like that.

      Perhaps I’ve been blinded by science, and I should really get my “research” from Joe Rogan and Aaron Rodgers. Not to mention the suggestion of that guy who once recommended the CDC look into bleach injections as a possible cure.

      Speaking of that guy, I heard him recently confuse himself in the middle of one of his word salads into thinking he beat Obama in 2016, that Jeb Bush (whom he defeated in the primary) that same year was the president who got us into Iraq, and that if we don’t stop Biden he’s going to get us into World War TWO. I’m pretty sure he’s been regularly vax’d, too, so maybe you have a point.

      As for the actual president, yes, he has gotten COVID more than once. For his age I’d say he fared pretty well. Might have something to do with, you know, the vaccinations. I recommend the study in JAMA for how the outcomes can differ without them for those at greatest risk.

Get the best of Indiana business news. ONLY $1/week Subscribe Now

Get the best of Indiana business news. ONLY $1/week Subscribe Now

Get the best of Indiana business news. ONLY $1/week Subscribe Now

Get the best of Indiana business news. ONLY $1/week Subscribe Now

Get the best of Indiana business news.

Limited-time introductory offer for new subscribers

ONLY $1/week

Cancel anytime

Subscribe Now

Already a paid subscriber? Log In

Get the best of Indiana business news.

Limited-time introductory offer for new subscribers

ONLY $1/week

Cancel anytime

Subscribe Now

Already a paid subscriber? Log In

Get the best of Indiana business news.

Limited-time introductory offer for new subscribers

ONLY $1/week

Cancel anytime

Subscribe Now

Already a paid subscriber? Log In

Get the best of Indiana business news.

Limited-time introductory offer for new subscribers

ONLY $1/week

Cancel anytime

Subscribe Now

Already a paid subscriber? Log In