Could a Shingles Shot Save Your Memory? Rethinking Dementia!

For decades, neuroscientists have promoted the idea that the cause of dementia is the accumulation of amyloid plaque in the brains of patients with Alzheimer disease. Drug companies spent billions to create drugs that rid the brain of amyloid. The benefits, if any, were barely detectable. A brand new study in the journal Nature (April 2, 2025) suggests that herpes viruses, especially varicella zoster, could be a culprit. That’s because the old shingles shot, Zostavax, reduced the risk of developing dementia by 20% over a 7-year follow-up period. (We interviewed the lead scientist, Dr. Pascal Geldsetzer, about this research when it was first announced. You can listen here.) A newer shingles shot, Shingrix, may be even more effective (Nature Medicine, July 25, 2024). What should you know about vaccines against dementia?

The Loudest Shouters Bet on Anti-Amyloid Drugs:

The neuroscience community is a kind of old boys’ network. Once these researchers latched onto amyloid plaque as the cause of Alzheimer disease (AD), they were mostly unwilling to consider other possibilities. We interviewed a key player in uncovering this mess on our radio show # 1416:

“Exposing Fraud and Arrogance in Alzheimer’s Research” 

This podcast is worth a listen because we interviewed Dr. Matthew Schrag, a neurologist who has challenged researchers who helped advance the amyloid plaque theory of AD. We also talked with Charles Piller, author of an essay in the New York Times titled “The Devastating Legacy of Lies in Alzheimer’s Science.” His book, Doctored: Fraud, Arrogance and Tragedy in the Quest to Cure Alzheimer’s, features Dr. Schrag and describes the way the neuroscience community created the amyloid plaque story that has been hard to budge.

The Overlooked Herpes Theory of Dementia:

There is no doubt that amyloid plaque accumulates in the brains of many patients with Alzheimer disease. But what triggers that amyloid accumulation? Could viruses be one of the pebbles that starts a mountain slide that leads to an avalanche we call dementia?

Viral infections cause a lot of mischief! One need look no further than COVID-19 to verify that there can be long-lasting complications after such illnesses. The neuroscience community has long ignored the idea that viruses might play an important role in the development of dementia.

Over 40 years ago, a pathologist named Melvyn J. Ball, MD, linked herpes simplex virus (HSV) type 1 to Alzheimer dementia. Dr. Ruth Itzhaki of the University of Manchester in England has also been studying the relationship between herpes viruses and Alzheimer disease since the early 1990s. Both of these creative thinkers were mostly ignored by the neuroscience community.

The latest study in Nature (April 2, 2025) targets a different herpes virus, varicella-zoster. It causes chickenpox in children and shingles in older adults.

The latest study on the shingles shot Zostavax is titled:

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

The authors of this new study discovered a natural experiment in Wales, UK:

“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.”

The citizens who got a shingles shot called Zostavax had better outcomes than those who were not vaccinated:

“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.”

A study published in Nature Medicine (July 25, 2024) revealed that the newer shingles vaccine (Shingrix):

“is associated with a significantly lower risk of dementia in the 6 years post-vaccination.”

That is way better than the pricey drugs the FDA has recently approved to treat Alzheimer’s disease. Maybe the experts should start considering shingles vaccines against dementia!

A VERY Short History of Vaccines:

Vaccinations are considered one of the great advances in modern medicine. Diseases like smallpox, polio, diphtheria, measles, whooping cough, influenza and tetanus used to kill hundreds of millions of people around the world.

People who survived their infection might be disabled for life. Polio victims sometimes needed leg braces or wheelchairs to get around. Those who caught smallpox were often left with disfiguring scars or blindness.

Nowadays, most of these dangerous diseases are preventable with vaccinations. Other infections, however, may have lasting consequences that scientists are just starting to recognize.

Infections That Can Cause Long-Lasting Complications:

Lyme Disease:

The bacterium Borrelia burgdorferi can cause chronic Lyme symptoms, even when an infection is treated with antibiotics. Symptoms may include fatigue, brain fog, body aches and heart damage.

ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome):

The cause of ME/CFS remains somewhat mysterious. People often complain of a flu-like illness. It may be caused by an enterovirus. Symptoms can include extreme exhaustion, brain fog, body aches, headaches, joint pain, GI problems and so much more.

Bartonellosis:

The Bartonella bacteria can cause cat scratch fever, trench fever and many long-lasting symptoms. This germ is spread by fleas, sand flies and body lice, to name just a few of the vectors. Veterinarians are especially vulnerable to bartonellosis because so many pets have fleas. Long-lasting symptoms of the disease include relapsing fever, eye problems, foot pain, anemia, fatigue, arthritis and brain fog, to name just a few.

Long COVID:

COVID-19 is the most recent example of residual symptoms brought on by an infection. It is estimated that 18 million Americans now suffer from long-lasting post-COVID conditions. Those include chronic fatigue, cardiovascular complications, neurological symptoms, brain fog and diabetes.

There are many other infectious agents that can also cause chronic symptoms. They include the polio virus, Epstein Barr virus, West Nile virus, dengue virus and many more viruses and bacteria. The old idea of one and done is long gone. Perhaps you noted that “brain fog” is a common complaint of patients who experience one of these infections.

Infections That Can Cause Long-Lasting Mischief:

Gum disease (periodontitis) is an infection of the tissues around the teeth. It has been linked to heart attacks, heart disease and strokes (Frontiers in Cardiovascular Medicine, Feb. 27, 2023).

Hard-to-treat adult-onset asthma may also be related to infection. Chlamydia pneumoniae causes sore throats, sinus infections, laryngitis and bronchitis in its acute phase. Symptoms sometimes last for several weeks.

According to the CDC, C. pneumoniae infections might also raise the risk of a person developing arthritis or atherosclerosis as well as asthma. These conditions may not show up until after the infection appears to be long gone.

A lot of people think of influenza as little more worrisome than the common cold. Now evidence from the Netherlands shows a clear link between flu infections and heart attacks (NEJM Evidence, July 2024).

Heart attacks were six times more likely to occur during the week after suffering an episode of the flu. There is evidence that vaccinating against influenza can also protect people from major adverse cardiovascular events (European Heart Journal Suppl., Feb. 14, 2023).

A New/Old Vision of Dementia:

Let me offer you a metaphor that might, or might not, be a fair representation of the origins of Alzheimer disease. Imagine a match being lit in a broom closet of a large house. If that match falls on a pile of rags, it might slowly start a smoldering fire. Over time, that fire could burn out of control. There would be a lot of smoke and eventually it would burn the house down.

Someone watching from outside might first see the smoke. Eventually that person would detect flames. Finally, the fire would become fully apparent and eventually the whole house would be demolished.

What if one of the metaphorical matches of Alzheimer’s disease is a viral infection? Trying to put out the fire by sucking up the smoke would be fruitless. The only way to prevent the brain from burning down would be to either prevent the match from lighting in the first place or putting out the fire before it could take hold.

Tens of billions of dollars have been spent creating and developing medications that eliminate beta amyloid plaque in the brain. If that sticky protein is equivalent to smoke from the fire, eliminating it would do little, if anything, to prevent the “burning” brain from continuing its downward spiral.

If, on the other hand, viruses are the matches, then vaccinating against the resulting sparks or treating with anti-viral medications might actually slow or stop the brain fire from progressing.

Could a Shingles Shot Vaccine Help Against Dementia?

Vaccines may play a key role in preventing dementia. There is growing evidence that herpes viruses could be contributing to the development of Alzheimer disease (Journal of Alzheimer’s Disease, Feb. 13, 2024).

Several vaccine shots have shown potential to reduce the likelihood of developing dementia. They include flu shots (NPJ Vaccines, March 2, 2024) and BCG vaccine used to prevent tuberculosis or treat bladder cancer (Journal of Alzheimer’s Disease, March 19, 2024). BCG stands for Bacillus Calmette-Guérin. It is a 100-year-old vaccine that was originally developed to fight TB.

Even more exciting, research suggests that people who get vaccinated against shingles (herpes zoster) lower their risk for dementia (Brain and Behavior, Feb. 2024).

This meta-analysis of five studies involving over 100,000 patients concluded:

“Our data demonstrated that patients who had herpes zoster vaccination were at a significantly lower risk of developing dementia.”

More Proof That We Could Use Vaccines Against Dementia:

A study last year in Nature Medicine (July 25, 2024) was titled:

“The recombinant shingles vaccine is associated with lower risk of dementia”

What is a recombinant shingles vaccine? It is Shingrix from GSK. It contains glycoprotein E (gE) from the chicken pox (varicella-zoster) virus. The vaccine is over 90% effective at preventing an attack of shingles.

The investigators compared Shingrix (FDA approved in 2017) to an older shingles vaccine (Zostavax) that was approved in 2006.

People who received the more effective shingles shot:

“…were at a lower risk of dementia in the next 6 years…translating into 17% more time lived diagnosis-free, or 164 additional diagnosis-free days among those affected.”

That isn’t to say the older Zostavax vaccine was ineffective, though. The meta-analysis of five studies described above (Brain and Behavior, Feb. 2024) concludes that all shingles vaccinations are associated with a lower risk of dementia.

It also appears that all vaccinations may reduce the risk of developing dementia. That is the conclusion of an article published in the Journal of Alzheimer’s Disease (Sep. 12, 2023):

“The Impact of Routine Vaccinations on Alzheimer’s Disease Risk in Persons 65 Years and Older”

They reviewed 16 million medical records from an insurance claims database. About 1.6 million senior citizens were followed for more than eight years. Those who were vaccinated for tetanus and diphtheria were 30% less likely to receive a diagnosis of Alzheimer disease. Shingles vaccinations (herpes zoster or HZ shots) lowered the risk by 25%. Pneumonia vaccines also reduced the likelihood of developing dementia by about 27%.

For our sophisticated readers, these were relative risk reductions. Absolute risk dropped by 2 to 3 percent.

The authors concluded:

“Using a retrospective cohort study, we found that there were significant decreases in AD for patients 65 and older who received a Tdap/Td [tetanus and diphtheria] vaccination (30%), an HZ [herpes zoster] vaccination (25%), or a pneumococcal vaccination (27%) versus separate unvaccinated groups over an 8-year period. Our main analysis results are consistent with other studies of these three vaccines suggesting a possible preventative effect on dementia.”

The Shingrix vaccine actually produced better results. People who received at least one dose of this shingles vaccine reduced their likelihood of developing Alzheimer disease by 73%.

The Shingles Shot Against Dementia:

An earlier study utilizing the Wales data suggested that the shingles shot could reduce the risk of developing dementia (MedRxiv, May 25, 2023). This study was published as a “preprint.” That means it had not yet been certified by peer review. That’s why the latest iteration of this original study is so convincing. The editors of the journal Nature require peer review and close scrutiny. The new publication (Nature, April 2, 2025) has been carefully reviewed.

How Could a Shingles Shot Protect Against Dementia?

The authors of this landmark paper suggest several plausible mechanisms. When a child catches chicken pox from the varicella zoster virus (VZV), the pathogen doesn’t disappear. Instead, the virus goes into hibernation in nerve cells (ganglia) around the spinal cord and brain. It can hang out for many decades without seeming to cause any mischief.

If the virus becomes reactivated, however, it can cause a whole lot of hurt. For one thing, shingles can be extremely painful. The rash literally hurts like hell. Sometimes the pain lingers for months or years because of lasting nerve damage.

The authors of the Nature article offer this explanation for herpesvirus-induced brain damage and shingles shot protection:

“There are already several lines of evidence on plausible mechanistic pathways that link VZV [varicella zoster virus] reactivations to dementia. Specifically, VZV reactivations have been found to lead to long-lasting cognitive impairment through vasculopathy, amyloid deposition and aggregation of tau proteins, neuroinflammation, as well as a similar spectrum of cerebrovascular disease as seen in Alzheimer’s disease, including small to large vessel disease, ischaemia [impaired blood flow], infarction and haemorrhage. As suggested by a recent study, it may also be the case that reducing subclinical and clinical reactivations of VZV reduces reactivations of the herpes simplex virus-1 in the brain through neuroinflammatory pathways. This mechanism would link VZV to the body of literature on the role of herpes simplex virus-1 in the pathogenesis of dementia.”

Interpretation:

OK, I apologize for quoting the scientists’ very technical description of what they think is going on. Here’s my interpretation of that technospeak.

The virus that causes shingles, varicella zoster, “wakes up” after lying dormant for decades inside our nerve cells. The authors also suggest that reactivation of the varicella zoster (shingles) virus may have a secondary impact and reactivate dormant herpes simplex virus (HSV-1). So, you get a double whammy of herpes virus activation: zoster and HSV-1.

When such viruses are reactivated, they cause a lot of damage. “Neuroinflammation” in the brain can harm blood vessels and cause lots of other mischief, including the buildup of amyloid plaque and nerve damage. This chain of events could ultimately lead to memory loss and many of the other clinical manifestations of dementia.

I want to emphasize that this is a “plausible mechanistic pathway.” It is yet to be proven. But it would explain why herpes viruses like varicella zoster and HSV-1 could trigger a cascade of events that ultimately lead to cognitive dysfunction. If this turns out to be supported by future research, it bolsters the idea of using vaccines against dementia.

Final Words:

The idea that viruses may contribute to neurological disorders is controversial. However, if vaccines could prevent or delay the development of dementia (or heart attacks), they might revolutionize our approaches to hard-to-combat cardiovascular and neurological conditions.

There is a growing anti-vax movement in the United States. That alarms me. I am not objective about this issue. That’s because I had polio as a child before there were polio vaccines. I also caught whooping cough long before there was a pertussis vaccine. Both diseases could have been fatal.

I still suffer from PTSD because of my days in a polio ward as a child. Children were dying all around me. Being restrained in traction when you are a little kid is a life-altering situation.

I am not advocating that everyone rush out and get a shingles vaccine. But I would hope that the anti-vax movement will not discourage people from considering the unexpected health benefits of such vaccinations.

Final-Final Words:

If you found our interpretation of the article in Nature (April 2, 2025) of interest, why not listen to our interview with the senior author? We spoke with Pascal Geldsetzer, MD, of Stanford University Medicine about his research when the preprint was first published. We also spoke with Bodil Weidung, PhD, of Uppsala University, Sweden. Both investigators have been involved in research indicating that herpes viruses could play an important role in the pathogenesis of Alzheimer’s disease. They describe the nature of their different studies and why neuroscientists need to start thinking creatively about ways to overcome dementia.

Here is a link to Show 1394:

“Viruses, Vaccines and Alzheimer Disease”

You can listen to the audio stream by clicking on the white arrow inside the green circle under the photo. Or you can download the mp3 file by scrolling to the bottom of the page under the “Listen to the Podcast” heading.

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