The shingles vaccine prevents dementia – an amazing scientific study!

I’ve decided to summarize the results of this important study, that demonstrates how prevention of shingles can delay the onset of dementia, because I wanted to provide you with access to accurate information, especially in light of popular media coverage.
But you must start by reading the basic post that explains what shingles is, including how it is associated to chicken pox, and how this virus lingers in the body following primary infection.
At the same time, we also have an excellent post on this website about the shingles vaccine, so make sure to read that one too.

Once you have read those two posts, you are dementia-free and you can now read about how to delay its onset even further.
The study I am referring to was published in the super prestigious medical journal Nature Medicine on the 25th of July, 2024, and you can find it in the following link.

What is the background to the current study?

I’ll keep this short, since you have already read my previous posts about this virus.
We have all had chicken pox in our childhood. Following that primary infection, the virus, called Varicella Zoster, remains in our body and can cause an outbreak several decades afterwards. Since we have all already had chicken pox and we have the antibodies against it, this outbreak is localized and spreads in a belt-like pattern, and it is referred to as shingles.
In recent years, two vaccines against shingles have been introduced and they are given to elders. The first one is called Zostavax – it was used for several years but has since disappeared from the world and has been replaced by a better vaccine.
The second vaccine is called Shingrix – this is the more successful vaccine that is given nowadays.
The question that was asked was whether people who received one of these two vaccines are more protected against dementia in their elder years.
Why are these two things even associated? Because we think that the presence or onset of this virus, that is dormant in our system, may have an accumulated effect on our brain cells that may then manifest in dementia.
Or, in other words, it is possible that the mere existence of the virus in our nervous cells is associated with dementia.

What is the basic scientific assumption behind this study?

The assumption, that has already been proven in previous studies, is that prevention of shingles delays/prevents dementia. This concept has already been proven in previous studies, but the proof was limited. Why was it limited?
a. The previous study compared a population that had been vaccinated to one that hadn’t been. One could claim that people that choose to get vaccinated are very different to those that choose not to.
b. Prevention of dementia was seen more in women, and less so in men.
c. The previous study assessed the effects of the old vaccine, Zostavax, and nowadays we use the newer vaccine.
Keep reading.

Methods of the study

Electronic charts belonging to patients in the United States of America were reviewed, and the primary outcome (dementia) was compared between vaccinated and unvaccinated populations. The type of vaccine was also included.

Results – does the shingles vaccine prevents dementia

Data was collected on three different study groups.
Over 100,000 people had received the first dose of the Zostavax vaccine between 2014-2017.
Over 100,000 people had received the first dose of the Shingrix vaccine, between 2017-2020.

What were the results? Were people who had received Shingrix more protected than people who had received Zostavax?

Absolutely!
Those who received the newer vaccine had a 17% longer period of time without dementia compared to those who received Zostavax (who are more protected from dementia than the unvaccinated population).
Or in other words, the group of people who received Shingrix were free of dementia for 164 more days compared to those who received Zostavax.
The good news is that these results were demonstrated both in women and men this time, despite the efficacy of prevention of dementia still being higher in women than it is in men.
And just to keep those who feel like there wasn’t a real control group to this study content – a comparison was made between adults who received an influenza or tetanus vaccine and those receiving shingles vaccine and the latter experienced a longer period of time where they were free of dementia.

What are the conclusions for this study?

In addition to the immediate conclusions which are that one must get their shingles vaccine (who is at high risk of getting the infection? Find out more here), there are enough conclusions here for health ministries to put together new guideliens and implement.
If I were to make any decisions on the recommended vaccines on a nationwide level – I would really urge people to take this one, because not only does it prevent shingles, it also has much farther implications.
For those of you chuckling and thinking ‘it’s only 164 days without dementia’ I tell you this:
a. 164 extra days without dementia: for both the individual and the society, that is a lot.
b. This is clear cut proof that there is certainly an association between the virus and dementia, and it is an opening for further research about the mechanisms behind cognitive impairment. Who knows how far our research will get?
And indeed, if I were to study dementia, I would try to find out what other strategies (and what are the specific mechanisms), related to Varicella Zoster, can prevent further neurological morbidity.