A drug dedicated to preventing Alzheimer’s disease may be years away, but new research suggests the vaccines and blood pressure medications that many older adults routinely take can lower the risk of dementia.
On the other hand, antihistamines and some anti-anxiety drugs have been shown to raise the risk of cognitive decline.
“The things that worsen memory decline tend to cause more inflammation,” says Neha Gandhi, MD, neurologist on the medical staff at Methodist Dallas Medical Center. “If we can manage these risk factors, that can essentially prevent or delay memory decline.”
HOW VACCINES HELP
Those annual flu and RSV shots may protect older adults from more than a nasty respiratory infection. They could lower the risk of developing Alzheimer’s disease.
A 2026 study in the journal Neurology found patients who received a high-dose influenza vaccine were less likely to develop the disease, with women benefiting more than men.
Similarly, a 2025 study by scientists at Oxford University reported a 29% reduction in dementia risk among patients who received an RSV vaccine.
Dr. Gandhi welcomes the studies that have led to a more holistic approach to preventing memory loss.
“I think the research is very empowering,” Dr. Gandhi says. “We have something in our control to prevent or delay dementia.”
Researchers made headlines last year when their study showed an association between the shingles vaccine and lower rates of dementia. And an experiment in Wales, published in 2025 in Nature, showed 20% lower dementia rates seven years after a widespread campaign to inoculate the aging Welsh population against herpes zoster, the virus that causes shingles.
Known as “off-target benefits,” the beneficial side effects of these vaccines are likely linked to the collateral inflammatory damage that infections like the flu and shingles cause in the nervous system.
In other words, a patient who avoids a bad case of the flu could also be spared a stroke or the narrowing of blood vessels that can outlast the initial infection.
LOWERING RISK
Diabetes, high cholesterol, and hypertension are all risk factors for dementia, and recent studies suggest medications to treat them can help prevent memory loss.
“The medications that are really helpful are the blood pressure medications,” Dr. Gandhi says. “Controlling your blood pressure slows memory decline by 12% to 13%.”
Research shows there is not one root cause of dementia, a diagnosis nearly 10 million people receive each year, according to the World Health Organization.
“There are three roads that can lead to brain damage,” Dr. Gandhi says. “The most important one is the chronic inflammation, the second is poor blood flow, and the third is the loss of connections between the brain cells and neurotransmitters that help with that.”
Medicines that treat these conditions work by reducing plaque buildup in arteries, relaxing blood vessels, and controlling blood sugar levels.
“The blood vessels that supply your brain, you have to keep them healthy,” Dr. Gandhi says. “By controlling these risk factors, the vessels will stay plaque-free, have less atherosclerosis, and your brain will have better blood supply.”
DRUGS THAT RAISE RISK
Other medicines like antihistamines, antipsychotics, and benzodiazepines could lead to a higher risk of developing dementia later in life.
- Antihistamines: drugs that block histamine release and treat allergies or cold and flu symptoms, like diphenhydramine and hydroxyzine
- Antipsychotics: medications that change the balance of chemicals in the brain
- Benzodiazepines: drugs that block the activity of nerves in the brain, like alprazolam and diazepam
“The things that worsen memory decline tend to cause more inflammation, disrupt the connections, starve your brain cells of the chemicals that are needed for memory formation,” Dr. Gandhi says.
Antihistamines are one of the most common types of anticholinergics, which researchers have found could increase dementia risk by about 50% with long-term use.
“Anticholinergics reduce acetylcholine in your brain, which is very important for your memory,” Dr. Gandhi says. “It works by inhibiting that neurotransmitter, which further aggravates your memory.”
PREVENTIVE MEDICINE
Taking care of your health before you reach old age could be the difference in having memory loss later in life, Dr. Gandhi says.
“Manage your blood pressure and cholesterol, stay socially active, get vaccines that are age-appropriate, and avoid meds that can worsen your cognitive decline,” she advises. “Those things have a profound effect on your brain health, and it does lower your dementia risk even if you are genetically predisposed.”
Prioritizing healthy habits while in middle age provides the most benefits later in life, Dr. Gandhi says.
“The benefit only happens if you are taking care of yourself in your midlife,” she says. “It’s better if you prevent things from happening, because your brain takes the insults silently for decades and decades before we see memory decline.”
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