Shingles Vaccine Linked to Lower Dementia Risk – Neuroscience News

Summary: A new study has found that getting vaccinated against shingles may reduce the risk of developing dementia by 20% over seven years. This conclusion comes from a natural experiment in Wales, where vaccine eligibility was determined by birthdate.

Researchers used rigorous statistical methods, typically seen in economics, to isolate the effect of the shingles vaccine from other factors. Their findings suggest that routine immunization could play an unexpected role in protecting brain health as we age.

Key Facts:

• 20% Risk Reduction: Shingles vaccination was linked to a 20% lower risk of dementia over seven years.
• Natural Experiment Design: Eligibility for the vaccine was based on exact birthdate, allowing a unique causal analysis.
• New Prevention Pathway: Findings point to potential public health strategies for reducing dementia risk.

Source: Johannes Gutenberg University Mainz

Vaccination to prevent shingles also reduces the risk of developing dementia in later life, according to a research paper published recently in Nature.

This conclusion is based on the analysis of data collected in connection with the introduction of a shingles immunization program launched in Wales in 2013.

Economists with their special expertise in statistical analyses have made a significant contribution to the corresponding study.

“We were able to apply our capabilities in statistics to medical data, thus forging a bridge between these two fields,” said Dr. Markus Eyting of Johannes Gutenberg University Mainz (JGU), lead author of the study.

Together with co-lead author Dr. Min Xie, a postdoctoral researcher at the Heidelberg Institute of Global Health, he demonstrated that the shingles vaccination was associated with a 20 percent reduction in the probability of a new dementia diagnosis over a period of seven years.

As noted in the article, “A natural experiment on the effect of herpes zoster vaccination on dementia,” this could raise various new possibilities for dementia prevention.

Electronic health records for Wales supply basis for statistical analysis

Dr. Min Xie identified the groundwork of what would represent a “natural experiment” created by the introduction of a herpes zoster vaccination program in Wales about two years ago. In the program, the eligibility to receive the vaccine was determined by an individual’s exact date of birth.

Those born before 2 September 1933 were automatically ineligible for life, while those born on or after 2 September 1933 were entitled to receive the vaccine.

“We can speak of a natural experiment in this context because this setting gives us the opportunity to compare individuals who had just turned 80 with those who had not quite reached 80 years of age,” Eyting explained.

Because the individuals in the study cohort were only a few weeks apart in age, the researchers could assume that vaccination was the only factor that set the groups apart.

“We then looked at the risk of developing dementia over the next seven years,” Eyting continued.

One of the main goals of the analysis was to identify a potential causal effect rather than just a correlation. In other words, the researchers were looking for a causal relationship between the shingles vaccine and the risk of developing dementia, not just a random connection between the two factors.

In economics, threshold values and target dates – in this case, the individuals’ birthdays – are often employed to test for causal effects using regression discontinuity designs.

“This method is widely used in economics but has not yet been adequately recognized as a tool for clinical research,” Eyting added.

In his view, regression discontinuity analyses offer many opportunities for evaluating the effectiveness of public health measures.

Markus Eyting is a postdoctoral researcher at the Gutenberg School of Management and Economics (GSME) of Mainz University and at the Leibniz Institute for Financial Research SAFE in Frankfurt.

His research focuses on experimental methods and survey and administrative data to study the interplay of beliefs and individual decision making with applications relating to health, discrimination, and machine learning.

Also involved in the study were Dr. Simon Heß of the Vienna University of Economics and Business, who supported the data analysis with his expertise in econometric methodologies, as well as researchers from Stanford University.

Eyting received the 2023 Young Economist Award from the European Economic Association (EEA) for a paper on the cause of discrimination.

About this vaccines and dementia research news

Author: Kathrin Voigt
Source: Johannes Gutenberg University Mainz
Contact: Kathrin Voigt – Johannes Gutenberg University Mainz
Image: The image is credited to Neuroscience News

Original Research: Open access.
“A natural experiment on the effect of herpes zoster vaccination on dementia” by Markus Eyting et al. Nature

Abstract

A natural experiment on the effect of herpes zoster vaccination on dementia

Neurotropic herpesviruses may be implicated in the development of dementia. Moreover, vaccines may have important off-target immunological effects. Here we aim to determine the effect of live-attenuated herpes zoster vaccination on the occurrence of dementia diagnoses.

To provide causal as opposed to correlational evidence, we take advantage of the fact that, in Wales, eligibility for the zoster vaccine was determined on the basis of an individual’s exact date of birth.

Those born before 2 September 1933 were ineligible and remained ineligible for life, whereas those born on or after 2 September 1933 were eligible for at least 1 year to receive the vaccine.

Using large-scale electronic health record data, we first show that the percentage of adults who received the vaccine increased from 0.01% among patients who were merely 1 week too old to be eligible, to 47.2% among those who were just 1 week younger.

Apart from this large difference in the probability of ever receiving the zoster vaccine, individuals born just 1 week before 2 September 1933 are unlikely to differ systematically from those born 1 week later.

Using these comparison groups in a regression discontinuity design, we show that receiving the zoster vaccine reduced the probability of a new dementia diagnosis over a follow-up period of 7 years by 3.5 percentage points (95% confidence interval (CI) = 0.6–7.1, P = 0.019), corresponding to a 20.0% (95% CI = 6.5–33.4) relative reduction.

This protective effect was stronger among women than men. We successfully confirm our findings in a different population (England and Wales’s combined population), with a different type of data (death certificates) and using an outcome (deaths with dementia as primary cause) that is closely related to dementia, but less reliant on a timely diagnosis of dementia by the healthcare system.

Through the use of a unique natural experiment, this study provides evidence of a dementia-preventing or dementia-delaying effect from zoster vaccination that is less vulnerable to confounding and bias than the existing associational evidence.