Could your annual flu shot and Alzheimer’s risk be connected? A large new study of nearly 200,000 older adults suggests they might be, and that the strength of the shot may matter. Seniors who got a high-dose flu vaccine had a nearly 55% lower risk of Alzheimer’s dementia, compared with about 40% for a standard-dose shot.
Here’s what the researchers found, what it doesn’t prove, and what it could mean for your next trip to the pharmacy.
Flu Shot and Alzheimer’s: What the New Study Found
The research comes from a team at the University of Texas Health Science Center at Houston (UTHealth Houston) and was published in the journal Neurology under the title “Risk of Alzheimer Dementia After High-Dose vs Standard-Dose Influenza Vaccination” (DOI: 10.1212/WNL.0000000000214782).
The key numbers, as summarized in UTHealth Houston’s release on ScienceDaily:
- The study analyzed data from nearly 200,000 men and women ages 65 and older.
- Standard-dose flu vaccination was associated with a 40% reduction in Alzheimer’s risk.
- High-dose flu vaccination was linked to a reduction of nearly 55%.
- The association was particularly pronounced among women, who appeared to benefit more from the stronger vaccine.
The senior author is Dr. Paul E. Schulz, a professor of neurology at McGovern Medical School at UTHealth Houston and director of its Neurocognitive Disorders Center. The corresponding author is Dr. Avram Samuel Bukhbinder, now a clinical neurology fellow at Massachusetts General Hospital and Harvard.
What Is a High-Dose Flu Shot?
A high-dose flu vaccine is a version made for older adults. It contains four times as much influenza antigen as a standard-dose shot. The extra antigen is meant to spark a stronger immune response in people 65 and older, whose immune systems tend to respond less vigorously to vaccines.
The CDC lists high-dose vaccines as a preferred option for adults 65 and older. Before 2022, the agency did not express a preference among injectable flu vaccines for that age group.
That history matters for the study. Because demand for high-dose shots sometimes outstrips supply, some seniors end up getting the standard dose. That natural variation let researchers compare two groups of vaccinated older adults.
How the discovery started
The idea came from an unexpected question. In 2022, Schulz’s team published research linking flu vaccination to lower Alzheimer’s risk in adults 65 and older. Public health officials who saw that work later asked whether different dosages made a difference.
“I was stunned that, as a physician, I didn’t know a higher dose was offered,” Schulz said in the release. Three years later, the team had their answer.
Why Would a Flu Shot Affect Alzheimer’s Risk?
Nobody knows yet. The researchers say the findings “raise important questions” about whether the immune response triggered by vaccination might influence biological processes involved in Alzheimer’s disease. They did not propose a specific mechanism and say more research is needed.
The stakes are high. In 2025, more than 7 million Americans ages 65 and older were living with Alzheimer’s, about 1 in 9 people in that age group, and that number is projected to more than double by 2050.
The Big Caveat: Association, Not Proof
Before you rewrite your health plan, keep the limits in mind. The researchers stress that the findings show an association rather than cause and effect.
That distinction matters. In observational studies, people who get vaccinated, or who seek out a specific vaccine, may differ in other ways. They might see doctors more often, have better access to care, or follow other healthy habits. Those differences can be hard to fully separate from the vaccine itself. A randomized trial would be the strongest way to test whether high-dose shots directly protect the brain.
The ScienceDaily release does not report absolute risk numbers, confidence intervals or the full follow-up period, so the full journal paper is the place to look for those details.
What This Means for You
The good news is that the main advice doesn’t depend on settling the Alzheimer’s question. Flu vaccination already protects older adults from serious illness, and high-dose shots are already a preferred option for people 65 and older.
- If you’re 65 or older, ask your pharmacist or doctor specifically for a high-dose or other preferred senior flu vaccine.
- Call ahead. Supply of senior-specific vaccines can run short, so confirm availability before you go.
- Help a parent or grandparent. Many older adults don’t know a higher-dose option exists, as Schulz himself admitted he didn’t.
- Don’t wait too long. Flu season is underway, and it takes about two weeks after a shot for protection to build.
- Protect your brain in other ways too. Physical activity, managing blood pressure and staying socially engaged are widely recommended for brain health.
For more on this season, read our update on where flu activity stands, our explainer on the CDC’s interim flu vaccine guidance, and our look at coffee and dementia risk.
This article is for general information and isn’t medical advice. Talk with your health care provider about which vaccine is right for you.
Stay tuned to USA One News for more health research that matters to your family.
