4 vaccines that are linked to a lower risk of dementia
Some vaccine-preventable diseases are linked to accelerated brain atrophy and increased dementia risk years down the line.
Vaccines don’t just protect us from infectious diseases or lessen their effects. Some are also associated with a reduced risk for dementia, research shows.“They’ll protect against these really potentially severe infections, especially in older adults, and preventing that alone is huge,” said Avram Bukhbinder, a resident physician at Massachusetts General Hospital in Boston who has conducted research on vaccines and dementia risk.“There seems to also be some kind of added benefit and ultimately it just adds a more compelling reason” to get routine vaccines, he said.Studies have found that many vaccines may be associated with a reduced risk of dementia — here are four of the most common ones with the strongest links.The flu shotAn estimated 47 million to 82 million people in the United States — about 13 to 24 percent of all people — caught influenza, or the flu, during the 2024-2025 season with 27,000 to 130,000 Americans dying as a result, according to preliminary data from the Centers for Disease Control and Prevention. (Flu season generally runs from October to May in North America.)Influenza and pneumonia — a potential complication of flu — are associated with five neurodegenerative diseases, including dementia and Parkinson’s disease, according to a 2023 study analyzing biobank data from over 400,000 people.“I don’t know how many times in the adult world we hear, ‘My loved one got flu, was in the hospital for a week or two, and it just was never the same.’ Like quickly went downhill from there,” Bukhbinder said.Many studies have found that flu vaccination is associated with a lower risk of dementia years later.In a 2022 study, Bukhbinder and his colleagues at the University of Texas Health Science Center at Houston examined a large health database of over 1.8 million adults ages 65 and over. They found that those who received at least one flu vaccine were 40 percent less likely to develop Alzheimer’s — the most common form of dementia — during the next four years.Getting the flu vaccine was also associated with a 17 percent reduction in dementia risk in a 2024 study of over 70,000 participants.The CDC recommends all people over 6 months old get annual flu shots, typically in September or October.Fewer than half of Americans typically get their flu vaccine each season.The shingles vaccineThe shingles vaccine has the strongest evidence for reducing the risk of dementia with multiple large-scale studies in the past two years corroborating the results of older studies.In one 2025 study, researchers tracked more than 280,000 adults in Wales and found that the shingles vaccine was linked with reducing dementia risk by 20 percent over a seven-year period.“There may be potential additional benefits beyond the protection that the vaccine provides for a particular condition,” said Pascal Geldsetzer, an assistant professor of medicine at the Stanford University School of Medicine and the senior author of the study. “So, that’s only an additional reason to get vaccinated.”A subsequent study examining over 100,000 patients in Australia similarly found that getting vaccinated for shingles was associated with reduced dementia risk.If you are eligible, you should probably get a shingles vaccine regardless of its chances of reducing your dementia risk. The vaccine reduces the reactivation of the varicella-zoster virus, which causes chicken pox in childhood and remains dormant in nerve cells afterward. When reactivated in adulthood, the virus manifests as shingles, which is characterized by a burning, painful rash and can sometimes cause lifelong chronic pain conditions or serious complications in a subset of people who get it.The CDC recommends two doses of a shingles vaccine for adults 50 and older or those 19 and older with a weakened immune system; 36 percent of eligible Americans got vaccinated in 2022.The RSV vaccineRespiratory syncytial virus, or RSV, is a common respiratory virus that can cause mild, cold-like symptoms in most people, but may cause severe infections in children as well as adults ages 65 and older. (The virus is the leading cause of hospitalization among American infants and causes an estimated 10o to 300 deaths in children under 5, and 6,000 to 10,000 deaths in people 65 or older, every year in the U.S.)A recent study tracking over 430,000 people found that the RSV vaccine (as well as the shingles vaccine) was associated with a reduced risk of dementia over 18 months compared with those who received the flu vaccine.The CDC recommends all adults ages 75 and older, as well as adults older than 50 at higher risk of RSV, get the vaccine.The Tdap vaccineSeveral studies have reported that the vaccine against tetanus, diphtheria and pertussis (or whooping cough), or Tdap, is associated with a reduced risk of dementia.One 2021 study with over 200,000 patients reported that older adults who received both the shingles and Tdap vaccines had further reduced risk of dementia compared with those who only received one of the vaccines.The CDC recommends routine Tdap vaccination for all adolescents and a booster for adults every 10 years. In 2022, about 30 percent of adults ages 19-64 who could be assessed had received a Tdap vaccine.How vaccines may reduce dementia riskResearch has shown that severe infections, including flu, herpes and respiratory tract infections, are linked to accelerated brain atrophy and increased risk of dementia years down the line.“We think it’s the uncontrolled kind of systemic inflammation that’s probably contributing to that,” Bukhbinder said. “And it’s very likely that they had the underlying Alzheimer’s or other dementia pathology already, but the inflammation is what pushed them over the edge.”Geldsetzer said that the varicella-zoster virus, which causes shingles, has the most clear biological links because it hibernates in our nervous system and can more directly affect the brain. (Getting a chicken pox vaccine in childhood can prevent this virus from taking hold in the first place.)Though different vaccines are linked to reduced dementia risk, there are inherent limitations to how the research was conducted. The link is associational, not causal, because the people who get vaccines may be different from those who don’t.For example, it could be that “those who are on average more health-motivated, have better health behaviors, are the ones who decide to get vaccinated,” Geldsetzer said. Even though researchers try to account for these confounding variables, it is not possible to fully filter out differences in health behaviors associated with dementia risk.But recent studies hint at a stronger link between the shingles vaccine and dementia-risk reduction. This research takes advantage of “natural experiments” because of arbitrary dates that the governments of Wales and Australia set for shingles vaccine eligibility; those born immediately before and after the eligibility date are probably not different and can be more directly compared. And when they are, those who got the shingles vaccines had lower risk of dementia, said Geldsetzer, who was an author on the Wales and Australia studies and is raising money to fund a randomized controlled trial.There are two broad biological hypotheses for how vaccines are linked to reduced dementia risk. Vaccines could reduce the risk of getting sick and infection severity, which have been linked to increased dementia risk.“I feel confident that that’s part of the story, but it’s not the whole story,” Bukhbinder said.Another, not mutually exclusive possibility is that the vaccine itself may activate the immune system in a beneficial way. Vaccination “may be honing or refining the immune system’s response,” Bukhbinder said.There’s “good evidence that what happens outside of the brain … seems to actually affect the inside pretty robustly,” Bukhbinder said.How to keep up-to-date on vaccines and reduce dementia riskVaccinations, like all medical treatments, can have some risks and side effects, so it is important to speak with your doctor about your particular health needs.However, “I would say by and far the benefits of getting these vaccinations almost incomparably outweigh the risks,” Bukhbinder said.In addition, 45 percent of dementia cases could be delayed or prevented with lifestyle and environmental changes, according to the 2024 Lancet Commission report on dementia.Do you have a question about human behavior or neuroscience? Email BrainMatters@washpost.com and we may answer it in a future column.
