The Promising Role of Vaccines in Combating Dementia

Vaccines have been instrumental in controlling infectious diseases over the past two centuries, saving millions of lives annually. The World Health Organization reports that vaccination efforts prevent between 3 to 5 million deaths each year from illnesses such as diphtheria, tetanus, influenza, measles, and more recently, COVID-19.

Traditionally, vaccines are known for their role in curbing the spread of infectious diseases. However, emerging research suggests that their benefits may extend beyond infection prevention. A groundbreaking study published in April 2025 in the journal Nature presents evidence that the herpes zoster (shingles) vaccine could significantly reduce the risk of developing dementia in the general population—by as much as 20%. This finding opens new avenues in understanding the potential of vaccines as tools for neurodegenerative disease prevention.

The study utilized a natural experiment in Wales, where a policy change in 2013 made the shingles vaccine available to individuals born on or after September 2, 1933. Those born before this date did not receive the vaccine, creating a natural control group. Researchers analyzed health records over a seven-year span, revealing that vaccinated individuals had a 20% lower likelihood of developing dementia, with women benefiting more than men. Crucially, the comparison groups were similar in age and health status, strengthening the study’s validity.

While the precise mechanisms are not yet clear, two main theories are proposed. The first suggests that the vaccine directly inhibits the shingles virus, which may contribute to dementia progression. The second posits that the vaccine enhances immune function—known as trained immunity—potentially providing broad protective effects against neurodegeneration.

Despite these promising results, experts emphasize the need for further research. Most notably, randomized controlled trials are essential to confirm causality and understand how vaccines might be integrated into dementia prevention strategies. Such studies would compare vaccinated and placebo groups over time to establish definitive benefits.

Dementia remains a major global health challenge, with recent studies estimating that the lifetime risk after age 55 is approximately 42%. The number of new cases is projected to double by 2060, underscoring the urgent need for innovative prevention approaches.

Current research also challenges longstanding views focused solely on amyloid plaque accumulation in Alzheimer’s disease. Despite modest success from amyloid-lowering therapies, their high costs and side effects limit widespread use. Conversely, evidence suggests that prior exposure to certain viruses and the use of routine vaccines might lower dementia risk, highlighting the potential of immune system modulation as a therapeutic target.

As scientific understanding evolves, vaccines may become a crucial component in strategies to prevent or delay neurodegenerative diseases. This optimistic outlook encourages the scientific community to explore unconventional pathways, fostering innovation in the fight against dementia.