Shingles vaccination appears to prevent dementia
Herpes viruses, including the chickenpox pathogen, have long been suspected of being linked to dementia. The new results on the vaccination against shingles support this hypothesis.
Vaccination against shingles apparently reduces the risk of dementia. This is the conclusion reached by a working group led by Markus Eyting from the Heidelberg Institute of Global Health based on data from unvaccinated people in Wales and those vaccinated with the live Zostavax vaccine. As the team reports in a preliminary publication, people in a group with a vaccination rate of around 50 per cent were one fifth less likely to develop dementia than an almost completely unvaccinated comparison group. The result supports the hypothesis that the chickenpox virus, the trigger for shingles, is involved in the development of dementia.
Dementia is a growing problem worldwide and there is still no effective treatment for the loss of mental capacity. However, it has been suspected for some time that infectious diseases could be involved in some of the dementias. Several studies have provided evidence that herpes viruses, in particular HSV-1 and the chickenpox virus, are associated with a higher risk of dementia. These viruses attack nerve cells and in some cases can trigger encephalitis. They also appear to damage the brain in subtle ways, contributing to Alzheimer's and other neurodegenerative diseases.
Shingles is a late consequence of an infection with chickenpox, in which the virus becomes active again and causes a painful rash. The Zostavax vaccine reduces the incidence of shingles by around half. In Wales, the vaccine is only offered to people born after 2 September 1933. This cut-off date made the working group's analysis possible. In the study, the team compared people born in the week before the cut-off date with those whose birthday falls in the week after. The vaccination rate for the latter was 47 per cent, while for the former it was close to zero.
This means that the study does not directly compare vaccinated and unvaccinated people. However, the working group argues that this means that the results are not distorted by differences between them that are difficult to determine reliably. For example, a higher willingness to be vaccinated could be associated with higher education and possibly a lower risk of dementia. In contrast, the two groups analysed in this study are easily comparable: There is no plausible reason why it should make a systematic difference whether someone was born in the week before or after 2 September 1933,
According to the team's analysis, dementia occurred around 20 per cent more often in the unvaccinated group than in the group with a 47 per cent vaccination rate over the seven-year period studied. The data also show that the protective effect is stronger in women than in men. This could be due to differences in the immune system or the fact that the chickenpox virus causes a higher proportion of dementia cases in women. The publication has not yet been independently verified, and the result still needs to be verified in further studies. However, the finding is not unexpected and is in line with the results of previous studies and the general state of research on neurodegenerative diseases and herpes viruses.
Spectrum of science
We are a partner of Spektrum der Wissenschaft and want to make well-founded information more accessible to you. Follow Spektrum der Wissenschaft if you like the articles.
[[small:]]
Cover image: Shutterstock / Melinda Nagy
Experts from science and research report on the latest findings in their fields – competent, authentic and comprehensible.