New research finds the shingles vaccine can also prevent dementia and cardiovascular disease

The shingles vaccine is really good at preventing shingles — about 98% effective, according to Corey Casper. But new research suggests it may also be really good at preventing other ailments, like dementia and cardiovascular disease.

That raises the question of why it is that a vaccine targeted at one illness can prevent others — and what the connection between them is.

Casper is chief research officer with Banner Health and a professor of Medicine and Clinical Translational Science at the University of Arizona. He joined The Show to talk more about this.

Banner Health

Full conversation

MARK BRODIE: What to you stands out about this research?

COREY CASPER: What's fascinating about the information that's coming out now about the shingles vaccine is that we have a vaccine that has an intended use, and it's incredibly good at that intended use. It is licensed for the prevention of shingles, which is an awful, debilitating disease. And this is one of the most effective vaccines that we have. So it's pretty much a home run for its intended purpose.

But what's really fascinating is that there is a large and accumulating body of evidence that suggests that there are additional benefits to this vaccine that range from protection from dementia, cardiovascular disease, and maybe even lifespan and longevity. And so it's fascinating from a public health perspective to see a vaccine now working in so many different ways. And from a biomedical perspective to try and understand why that's happening is just an incredibly exciting opportunity.

BRODIE: Well, I'm curious about what this might mean, as you say, because I wonder if the fact that the shingles vaccine helps with things like, for example, dementia and maybe overall longevity, does that tell us anything about those other issues that we maybe don't know already?

CASPER: 100%. There's so much that this vaccine is teaching us, or at least encouraging us to ask more questions about, which is really how great research starts. So this vaccine, for your listeners who may not know this, is active against a virus. So the virus that causes chickenpox is a virus that's known as varicella zoster virus.

That virus is one 90% of people have either come across or now have been vaccinated against as a child. But that virus is one like all of the viruses in that family, that when you were infected with, goes dormant in your body lifelong. And it can reactivate at times when your body is under stress or when your immune system is not able to control that virus.

So when you get the virus as a younger child, you get chickenpox. When the virus returns after laying dormant in your nerve cells for many, many decades, it comes back as a condition called shingles, having a vaccine to prevent that is anyone who knows anyone who's had shingles. That is just an incredible gift to us.

So first, a priori, you would think that the way this vaccine works in its effect is by preventing the effects of this virus. That's interesting because this virus has not been formally associated with dementia. So why would a vaccine against this virus protect you against dementia? And that's where an incredibly interesting body of work is now emerging.

And I'm happy to describe that.

BRODIE: Yeah, I mean, what are researchers finding about any potential connections between shingles and dementia at this point?

CASPER: Yeah. So what began to happen and what, what kind of got called to our attention is we now have the ability to look at huge data sets of people engaged in health care that we never had an opportunity to study the way we do now.

But what we were able to find in several, now up to four very large population-based studies of hundreds of thousands of people is this association that people who got the shingles vaccines, and I say vaccines because there's more than one, but people who got the shingles vaccines seem to have a risk of dementia, which is especially Alzheimer's dementia, but all dementias, which are reduced between 20 and 40%.

Now, that's pretty incredible. If I told you that I had a drug that would reduce your risk of developing dementia by 40%, I can promise you there'd be a line out my door to take it. And we actually seem to have that drug. So the evidence first accumulated by these large population-based studies, We just made the observation that people who got this vaccine seem to be at lower risk for developing dementia.

But we don't actually, that's not causation, that's just association. We just know that somehow those things are associated. Now, unfortunately, we don't have better evidence, and better evidence is usually what's called a randomized controlled trial.

We take an individual and we take some and we give them the intervention and we take others and we don't give them the intervention. And we look to see if an outcome is less common. We don't have that level of evidence right now, although we are currently planning trials here at Banner and to look at these vaccinations in exactly that fashion.

BRODIE: Do you have any hypotheses about the potential connection between shingles and something like dementia?

CASPER: Yeah, I do. So I think there's a couple of different ways where this might be related. So the first and most obvious way is that these viruses we know are what we call neurotropic. They home to your neurons or your nerve cells. So it is not inconceivable to think that individuals who have this virus and who have the virus replicating inside of nerve cells in the brain could have inflammation, and that inflammation then could lead to these plaques and tangles that we know are associated with Alzheimer's disease.

So that's what I would call a direct effect. The virus is doing something in your brain that is prevented by the shingles vaccine. Now, while that's plausible, I don't think that's the only way that this vaccine is working. I think that there are additional ways. There's two different types of the shingles vaccine, and what we now know is that both forms of the vaccine seem to reduce the risk of dementia.

But what's fascinating is that now there is another vaccine that has that same strong immune stimulant, that same adjuvant, and that's the vaccine that is against a virus called RSV, a pneumonia virus, that we now know that patients who get that vaccine also seem to be at lower risk of dementia. So that, to me, because that vaccine is targeted at a different virus, means that there's an effect that is not solely due to the virus.

And that is rather what we think of something called trained and adaptive immunity. So these adjuvants increase your body's ability to process and respond to a broad range of infections and to regulate inflammation. And so I think what might be happening is that there actually may be two different ways that the shingles vaccine is acting.

First, by a direct effect on the virus. Second, by reprogramming the immune system and changing the way it reacts in an inflammatory way to different types of infections.

BRODIE: In the universe of research into dementia, into cardiovascular disease, into aging, how big of a role might the implications of the shingles vaccine play relative to all of the other research going on into these areas of medicine?

CASPER: Yeah. The implications of understanding why the shingles vaccine protects you against aging, cardiovascular disease and dementia, the implications of that are huge. What I think we'll learn, and we learn more every day. What I really think the future of medicine is, is understanding what causes inflammation in the human body. What are the different types of inflammation, and how do we do something to modify that?

So what we know is that most of the diseases that we see as we get older, cancer, cardiovascular disease, dementia, arthritis, metabolic diseases like diabetes, all of these can be attributed to inflammation. And so I think if we understand how a vaccine like the shingles vaccine is modifying inflammation, then I think we will understand other ways to modify inflammation.

Right now, the only way we modify inflammation is with some very crude anti-inflammatories. But if we can get better at that, I think we can really allow people to live longer and healthier lives.