In an exclusive interview with Conexiant, Dr. Geldsetzer discussed the study and its implications.

What are the implications of this study? What are the next steps that you want to take?

Dr. Geldsetzer: If the shingles vaccine really prevents or delays dementia, and with this new study, also appears to have benefits for those who already have dementia, then this would be a hugely important finding for clinical medicine, population health, and research into the causes of dementia. But what we will really need to convince the public health and medical community is a clinical trial. I'm currently trying to raise funds to conduct such a trial. I'm trying to raise these funds from private and philanthropic foundations because we want to trial the live-attenuated vaccine (which is the vaccine for which we have generated our compelling body of evidence), which is off-patent. So, if there is anyone out there who might be interested in helping to fund such a trial to definitively test if shingles vaccination prevents or delays dementia, it'd be great if they could get in touch with me.

What makes this study unique?

Dr. Geldsetzer: There have been many analyses in electronic health record and medical claims data that have found that receiving a given vaccine is correlated with a reduced risk of dementia in the future. These studies have all compared those who do get vaccinated with those who do not. The critical limitation of this research is that we know that the health behaviors of those who get vaccinated are different from those who do not, and we have very little, if any, information on these behaviors in electronic health record or medical claims data. We, for instance, do not know about dietary behaviors or physical activity levels. We, therefore, don't know if we're merely looking at correlations or actual cause and effect.

Our study takes a fundamentally different approach and, thus, provides a very different level of evidence. In medicine, what you need to prove that an intervention, like a medication or a vaccine, works is a randomized trial. So, you get, say, a thousand study participants and for each of them you throw a coin to assign them to getting the vaccine or no vaccine. What's so powerful about this is that we then know that on average, the vaccine and the no vaccine group should be similar to each other and so they are good comparison groups because all that differed for them is whether the coin landed on heads or tails.

What's so special about our study is that we take advantage of a very similar scenario to a randomized trial. In Wales, when they rolled out the shingles vaccine back in 2013, they said that if you had your 80th birthday just prior to the start date of the program, you were ineligible and you remain ineligible for life. While if you had your 80th birthday just after, you were eligible for at least one year. We see in our data, that just a one-week difference across this date-of-birth cutoff means that you go from essentially no one getting vaccinated to about half of the population getting vaccinated. So, this is just like a randomized trial! We have a vaccine-eligible and a vaccine-ineligible group for which we know that they should be on average similar to each other, and therefore good comparison groups, because all that's different about these two groups is whether they were born a few days earlier or a few days later.

Another important aspect of our research that makes this research stream particularly exciting is that we see the same protective effect from shingles vaccination for dementia in dataset after dataset – in different populations and different countries that rolled out the vaccine in a similar way as Wales did.

What is the key takeaway?

Dr. Geldsetzer: For the first time, we now have evidence that likely shows a cause-and-effect relationship between shingles vaccination and dementia prevention and treatment. We find these protective effects to be large in size –  substantially larger than those of existing pharmacological tools for dementia.

He also provided several videos online that further explain the research: 

https://www.youtube.com/watch?v=0xiTUvSzouw

https://www.youtube.com/watch?v=wZu28zr_jgU

https://www.youtube.com/watch?v=unnePZUqi1o