Some vaccines, along with heart medications and other drugs, appear to have a protective benefit. GUEST BLOG / By Dana G. Smith, New York Times, Health Reporter--Getting your annual flu shot may come with a significant side benefit: helping to protect you from dementia.
--Flu Vaccines
Numerous studies have found that older adults who were vaccinated against the flu had a lower risk of developing dementia in the years that followed than those who had not been vaccinated. In one study, the risk was as much as 40 percent lower.
Research published earlier this month has bolstered that evidence, showing that older adults who were given a higher dose of the flu vaccine — commonly recommended for people 65 and over — had an even lower probability of developing Alzheimer’s disease compared with those who received the standard dose.
Other common medications have also been found to decrease people’s risk of dementia. The challenge for scientists, though, is determining whether the drugs are directly benefiting the brain or whether there’s just a correlation between them.
The flu vaccine is a good example of this. “People who tend to get vaccinated are the people who go to see a doctor, and then they follow the directions to take their blood pressure pills and cholesterol pills, which also reduce the risk of Alzheimer’s,” said Dr. Paul Schulz, a professor and neurologist at UTHealth Houston who led the new study.
But because everybody in that study got an influenza vaccine, and the higher dose offered more protection, the findings suggest there is something about the vaccine itself, rather than people’s behavior, that lowered the risk, Dr. Schulz said.
Here are a few more drugs that scientists are investigating for their potential to reduce dementia risk.
--Shingles Vaccine
Excitement is especially high for the shingles vaccine, which has some of the strongest research behind it. Studies from around the world have found that people who received the vaccine had a lower risk of developing dementia, often by about 15 to 20 percent. Much of the research has been done on an older form of the vaccine, but at least one study indicated that a newer version more commonly prescribed in the United States, called Shingrix, could offer an even greater benefit. It (along with the flu vaccine) appears to be especially protective against dementia in women.
Researchers say they’re relatively confident that the vaccine itself is providing protection because its initial rollout in a few countries created a sort of natural clinical trial.
“I think at this stage, it’s a really compelling body of evidence of a cause and effect relationship,” said Dr. Pascal Geldsetzer, an epidemiologist at the Knight Initiative for Brain Resilience at Stanford who conducted some of the research.
Here’s more on our process.
There are a couple of theories about how vaccines might reduce the risk of dementia. One is that by protecting people from getting an infection, a vaccine prevents the immune response and especially the inflammation that comes with it. (Inflammation is a known contributor to dementia.) This may be especially relevant for shingles, since the virus initially replicates in the nervous system and can cause inflammation in the brain.
It’s also possible that the vaccines themselves might alter the immune system in a way that directly affects, and protects, the brain.
--Cholesterol and Blood Pressure Medications
Several studies have found that both statins and drugs that treat hypertension are associated with a roughly 10 to 15 percent reduced risk of dementia.
Many researchers think these drugs protect people’s brains by helping to manage blood pressure and cholesterol, both of which are risk factors for dementia. However, as with vaccines, people who consistently take their prescribed medications may have other healthy behaviors that could also lower their risk.
Most of the research is observational, but there have been a few clinical trials that have tried to more directly investigate the connection between these drugs and dementia. The results have been mixed. A 2025 trial from China found that people with high blood pressure who were given a medication for hypertension had lower rates of dementia four years later. But a 2009 trial that tested statins in people who had vascular disease or were at high risk for it did not find a benefit in preventing cognitive decline.
There’s also an open question over whether people who don’t need the medications for heart health could take them for dementia prevention, said Geoffrey Joyce, a professor of pharmaceutical and health economics at the University of Southern California. There are two large trials currently investigating whether statins might be useful in this way.
--Anti-Inflammatory Drugs
Since inflammation in the brain is a known contributor to Alzheimer’s, it’s conceivable that anti-inflammatory medications could provide protection by helping to reduce it in the brain as well as systemically. A recent large review paper listed anti-inflammatories as one of the classes of drugs that may reduce dementia risk.
David Llewellyn, a professor of clinical epidemiology and digital health at the University of Exeter Medical School in England who led the review, said he thought “the anti-inflammatory story” made sense scientifically.
But studies looking at the connection, especially with nonsteroidal anti-inflammatory drugs, have been mixed. Some have found a lower risk of dementia from ibuprofen use, while others showed no connection or even an increased risk. And a Cochrane review published in 2020 concluded there was “no evidence to support the use” of aspirin or other NSAIDs to prevent dementia.
--Diabetes Drugs
Diabetes is associated with an increased risk of dementia, and a few drugs for Type 2 diabetes, including metformin and a class of medication called sodium-glucose cotransporter 2 (SGLT2) inhibitors, appear to modestly lower that risk, though some studies don’t show an effect.
The potential benefit is thought to largely stem from the medications’ ability to help control insulin and blood sugar levels, which affect brain cell health. There is also some evidence, mostly from animals, that the drugs help to reduce inflammation and may even lower levels of amyloid beta in the brain, a key protein involved in Alzheimer’s.
Clinical trials investigating whether these diabetes drugs can be beneficial in dementia are ongoing. A few observational studies have also found that people with diabetes who took the newer GLP-1 medications had a lower risk of developing Alzheimer’s, even by as much as 45 percent, according to some reports.
Based on that evidence, and research in mice showing the drugs can reverse cognitive impairment, two clinical trials recently tested whether a pill form of Ozempic could also help slow cognitive decline in people with Alzheimer’s. But the trials found no benefit, and excitement about the use of GLP-1s as an Alzheimer’s treatment has died down significantly. More research is needed to determine if they indeed lower the risk of dementia.
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Dana G. Smith is a Times reporter covering personal health, particularly aging and brain health.
