In the Fight Against Dementia, Vaccines Hold Tantalizing Promise
For decades, various vaccines have helped prevent or reduce the spread of infectious diseases, resulting in the saving of many lives. New research now suggests that vaccines can do even more like preventing dementia.
A study, published in the journal Nature in April 2025, found that the shingles vaccine—the one that protects against herpes zoster—may also reduce the risk of developing dementia. In fact, the study showed that people who received the shingles vaccine had up to a 20 percent lower risk of dementia compared to those who did not receive the vaccine.
While the study does not definitively state that the shingles vaccine guarantees protection against dementia, scientists and medical professionals believe that the new research suggests the vaccine offers an additional benefit beyond just preventing shingles.
A team of physician-scientists at the University of Illinois at Chicago views this study as an exciting step forward in dementia research.
“We believe that this study potentially opens the door to other breakthroughs in understanding and treating dementia and other degenerative disorders of the brain,” Jalees Rehman, Department Chair and Professor of Biochemistry and Molecular Genetics, and Anand Kuma, Professor and Department Head of Psychiatry, wrote for The Conversation.
Results from the new study, as well as other related studies, suggest that vaccines may play a more significant role beyond infectious diseases, according to Rehman and Kuma. In addition, the studies also raise “provocative questions about how vaccines work and how our immune system can potentially prevent dementia,” the team said in their article.
How vaccines might be protective
Rehman and Kuma wrote that one scientific explanation why the shingles vaccine might reduce the risk of dementia is that it protects against the shingles virus, which some studies suggest can increase the risk of dementia.
It’s also possible that the vaccine offers protection by activating the immune system and training it to respond better over time. Through this type of “trained immunity,” the immune system gets stronger by repeated exposure to vaccines or viruses, according to the physician scientists.
Rehman and Kuma pointed out that the study did not look at different kinds of dementia, such as dementia caused by strokes versus Alzheimer’s disease. Additionally, the study only analyzed people’s health records, so it cannot draw any definitive conclusions about how the vaccine may be protective.
The physician scientists noted that previous studies based on health records suggest that past exposure to viruses increases the risk of dementia, while routine vaccines, such as those against tetanus, diphtheria, pertussis, pneumonia, and shingles, reduce the risk.
Rehman and Kuma recommended that the next step for researchers to take would be to have a “prospective, randomized, double-blind, placebo-controlled study,” which is considered the “gold standard” for clinical trials in medicine. The clinical trial would directly examine how the herpes zoster vaccine compares with a placebo in its ability to reduce the risk of dementia over time.
“Such studies are necessary before any vaccines, as well as other potential therapies, can be recommended for routine clinical use in the prevention of dementia,” Rehman and Kuma wrote.
Dementia Cases Expected To Increase Over the Next Four Decades
Research on dementia prevention is crucial now that statistics show the number of people suffering from neurodegenerative diseases is expected to rise over the next four decades.
Dementia is an umbrella term for various diseases that can cause loss of memory, language, problem-solving skills, and other cognitive abilities, which are severe enough to interfere with daily living activities and independent functioning.
The most common form of dementia is Alzheimer’s disease, which accounts for 60-80 percent of cases, according to the Alzheimer’s Association. Over seven million adults aged 65 and older are living with Alzheimer’s disease, according to the Alzheimer’s Association’s 2025 Alzheimer’s Disease Facts and Figures report.
A January 2025 study estimates that the lifetime risk of developing dementia after age 55 is 42 percent, more than double earlier estimates. The dementia risk was 4 percent by age 75, and 20 percent by age 85, with the majority of risk occurring after age 85.
The study also projected that the number of new cases of dementia in the United States would double over the next 40 years, from about 514,000 cases in 2020 to 1 million in 2060.
Physician Scientists: Innovation in Vaccine-Dementia Studies Needed
Rehman and Kuma suggested that future studies examining how a vaccine influences dementia risk could benefit from including individuals with specific types of dementia, as different forms of dementia may require distinct treatments.
Alzheimer’s has been at the forefront of scientific discussion, primarily because it is the most common type of dementia. However, there is no cure for the neurodegenerative disease.
For the past 20-30 years, the amyloid hypothesis has been the main focus in the scientific community regarding Alzheimer’s. Research suggests that the buildup of a protein called amyloid in the brain contributes to the development of Alzheimer’s disease. As a result, most of the experimental therapies for Alzheimer’s have been on reducing the levels of amyloid in the brain.
“However, results to date have been modest and disappointing,” Rehman and Kuma wrote. “The two recently approved amyloid-lowering therapies have only a minimal impact on slowing the decline, are expensive, and have potentially serious side effects. And no drug currently approved by the Food and Drug Administration for clinical use reverses the cognitive decline.”
Scientists sometimes tend to stick to “older, familiar models of disease,” be slow to embrace new ideas about disease, and have a “reluctance to move in more unconventional directions,” according to Rehman and Kuma.
“Yet the process of doing science has a way of teaching researchers like us humility, opening our minds to new information, learning from our mistakes and going where that data takes us in our quest for effective, lifesaving therapies,” Rehman and Kuma wrote. “Vaccines may be one of those paths less traveled. It is an exciting possibility that may open the door to other breakthroughs in understanding and treating degenerative disorders of the brain.”
Source Links:
https://theconversation.com/vaccines-hold-tantalizing-promise-in-the-fight-against-dementia-257807
https://www.alz.org/alzheimers-dementia/what-is-dementia
https://www.alz.org/news/2025/facts-figures-report-alzheimers-treatment
