The painful belt rose arises when varicella zoster viruses become active in the body again-the viruses that cause chickenpox. Because this rebuilt occurs especially in old age, older people from 60 are recommended to vaccination against shingles. But this vaccination could have another positive side effect: it also reduces the risk of dementia, as a new study has now confirmed. Seniors who have been vaccinated by around 20 percent less often fall ill from dementia as non -vaccinated peers. This protective effect of belt rose vaccination in women-why, has not yet been clarified. However, this could be related to the generally stronger immune response of women on vaccinations and infections. According to the researchers, their results confirm that viruses that affect the nervous system can increase the risk of dementia. The belt rose vaccination could therefore be a simple and favorable means of prevention.
The Varicella Zoster virus (VZV) belonging to the herpes viruses can cause two different diseases. When it comes to initial infection with the pathogen – mostly in childhood – the pathogen triggers chickenpox – itchy pustules are typical of this all over the body. Usually the chickenpox are over after around a week, but not the infection with the triggering virus. Like almost all herpes viruses, Varicella zoster remains in the body for life. The viruses survive in a kind of hinges in the nerve ending and further nerve fibers without causing symptoms. According to estimates by the World Health Organization WHO, around 95 percent of all adults are latently infected with Varicella Zoster. However, if the immune system of the infected weaker becomes weaker – due to a different illness or old age – the herpes viruses can awaken from their latency and multiply and spread again. The result is a shingles. Typical for them is a very painful rash on one side of the fuselage, less often on the head. Paralysis and meningitis can also occur. That is why vaccination against shingles is recommended for older people – in Germany it is a cash benefit in Germany from the age of 60.
A “natural experiment”
There has also been suspicion that herpes viruses and in particular Varicella Zoster play a role in neurodegenerative diseases such as Alzheimer’s and other dementia. For this, evidence of this provides an increased occurrence of certain herpes viruses in the brain of died Alzheimer’s patients, but also laboratory tests with tissue cultures of human brain cells. Conversely, there was already the first indication that a belt rose vaccination could reduce the risk of dementia. Studies show lower dementia rates for vaccinated seniors. However, it has so far been difficult to rule out study -related distortions. “All of these associative studies suffer from the basic problem that people who are vaccinated have a different health behavior than people who do not want to be vaccinated,” explains senior author Pascal Gate replacement from Stanford University. “In general, these studies were therefore not considered solid enough to derive recommendations from it.”
However, a “natural experiment” has now given the start of money, initial author Markus Eyting and her colleagues, the chance of examining the connection between belt rose vaccination and risk of dementia without these distortions. This was made possible by a vaccination program that was introduced in Wales on September 1, 2013. The special feature: Because the living vaccine used against belt rose was scarce, only those for vaccination were permitted that were not yet 80 years or older on this date. That meant: In extreme cases, a 79-year-old was allowed to be vaccinated on September 2, a person who had not become 80 the day before. This is exactly what made a start -up and his team for their study: they compared the health data and in particular the dementia rates of the seniors that occurred in the course of the following seven years, who had become 80 in the week before the cut -off date and therefore did not receive any vaccination with those of seniors who only became 80 a week after. Because there are just as many groups of vaccinations and those who want to vaccination in both groups, but only one group was able to preserve vaccination, this minimizes the otherwise typical distortion. “They are similar, except for this tiny age difference,” explains money setpers. The researchers were therefore able to compare whether these two cohorts differed in the seven years in relation to their dementia rates.
Clear protection effect of vaccination
The evaluation actually resulted in a difference-not only when the belt rose occurs, but also with regard to the frequency of dementia in both groups: the seniors who had received a belt rose vaccination rarely developed a dementia than the control group of the old test subjects for one week. The risk of dementia was 20 percent lower with the vaccination, as the researchers determined. This difference was also preserved when they took into account possible other influencing factors. For example, there was no difference in the level of education, in other diseases such as diabetes, cancer or cardiovascular disorders or other vaccinations. “It was a really striking finding,” says Geldetzer. “This large signal of a protective effect was there, no matter how to look at the data.” The “natural experiment” thus confirms the information from previous studies, according to which vaccination against belt rose significantly reduces the risk of dementia. In the past two years, money seters and his team have also checked the results from Wales based on health data from other countries such as England, Australia, New Zealand and Canada, in which similar vaccination programs have been introduced. There was also a protective effect of the belt rose vaccination before dementia.
However, the analyzes also showed that the protection effect of vaccination in women was more pronounced than in men. It is still unclear why this is the case. However, the team suspects that this is related to known differences in the immune response of women and men: Typically, the female immune system reacts to infections and vaccinations with stronger antibody distribution, at the same time women tend to tend to become autoimmune reactions. It has also not yet been clarified why the belt rose vaccination has a protective effect against dementia and what role the Varicella Zoster virus plays for the origin of dementia. According to money seters and his colleagues, however, several mechanisms are suitable. So the herpes virus could trigger an autoimmune reaction that damages the nerves and the brain over time. It would also be conceivable that the latent presence of the Varicella-Zoster viruses causes subliminal, chronic inflammation in the nervous system that promote neurodegenerative processes. And finally it could be that vaccination stimulates the immune system and that this also has positive effects on the processes that trigger dementia in the brain.
Regardless of the concrete mechanism, the researchers see their results a strong plea for shingles vaccination. “Because if these findings are causal, then the Varicella-Zoster-Vakzine are far more efficient and cost-effective than all previously existing pharmaceutical prevention measures,” stem and his colleagues.
Source: Markus Eyting (Stanford University, California) et al., Nature, DOI: 10.1038/S41586-025-08800-X