Study raises hopes that shingles vaccine may delay onset of dementia

After discovering that a recently licensed shingles vaccine was associated with a significant decline in dementia diagnoses in the six years following vaccination, researchers have rekindled hope for postponing dementia.

Based on US medical records, the discovery implies that the vaccine may postpone the beginning of dementia, the main cause of death in the UK, in addition to its other health benefits of preventing shingles, a painful and occasionally deadly ailment in the elderly.

The study’s first author, Dr. Maxime Taquet of the University of Oxford, stated that the findings were consistent with the theory that shingles immunization may guard against dementia. “These findings could have significant implications for health services, public health, and older adults if validated in clinical trials.”

The herpes zoster virus is the cause of shingles, which can recur in persons who have already experienced chickenpox. Following the introduction of the Zostavax shingles vaccine in 2006, several research revealed possible associations between the vaccine’s recipients and a decreased incidence of dementia.

In October 2017, a swift changeover occurred in the US regarding the shingles vaccination. Those who received their shots before that date received Zostavax, while those who received their shots after that date often received Shingrix, thanks to the development of a new and more effective vaccine.

About half of the more than 200,000 US residents who received shingles vaccinations—including the new vaccine—had their health data examined by the Oxford team. When comparing Shingrix to Zostavax, the risk of dementia decreased by 17% over the course of the following six years for the former group.

That adds up to an extra 164 days, or almost six months, of life without dementia for individuals who went on to develop it. Women experienced the effect at 22% compared to men’s 13%.

The researchers next looked at dementia rates in recipients of additional vaccinations. They report in a paper published in Nature Medicine that recipients of Shingrix had a 23–27% decreased risk of dementia compared to recipients of the flu, tetanus, diphtheria, or pertussis vaccines. Prof. John Todd of Oxford University, one of the paper’s authors, consults for GSK, the company that makes Shingrix, but the researchers said the study was carried out independently of the pharmaceutical corporation, who was only made aware of the work after it was accepted for publication.

Shingrix was made available to anyone turning 65 by the NHS last year. According to Taquet, “if this is indeed a causal effect, then once people start taking the Shingrix vaccine, we would see a reduction in dementia in the UK.”

In the UK alone, there are over 900,000 individuals with dementia, out of over 55 million worldwide. The illness affects one in three people at some point in their lives, and while medications that seem to reduce the disease’s progression have just been approved, there is currently no known treatment.

Although the most recent trial does not demonstrate that Shingrix prevents dementia, Prof. Paul Harrison, a senior author on the study, stated that additional teams were investigating the possibility. It is unknown how the vaccine prevents dementia, if it works. One theory is that dementia develops as a result of pathological alterations brought on by the return of the shingles virus. An further factor is that the vaccination contains substances known as adjuvants, which strengthen the immunological response to the shot.

It’s also uncertain if the vaccination would wear off too soon or if it would be more successful in preventing dementia in younger recipients, such those in their 50s.

“It will be interesting to see if more people choose to take [Shingrix] when they’re offered it, if these data become public,” Harrison said. “I don’t think people should start demanding the vaccine because they believe it will lower their risk of dementia,” the author says.

“This is a significant result, comparable in effectiveness to the recent antibody drugs for Alzheimer’s disease,” stated University of Manchester biochemistry professor Andrew Doig. One straightforward and affordable strategy to reduce the risk of Alzheimer’s disease may be to provide the recombinant shingles vaccine.

The [new] vaccine now has to be tested in a clinical trial where patients receiving it will be compared to those receiving a placebo. This is the most dependable method of determining the vaccine’s effectiveness. We also need to determine whether vaccinations at a younger age are appropriate and for how long the effect might remain. Given that Alzheimer’s disease can develop decades before symptoms appear, individuals in their 40s or 50s may benefit even more from the vaccination.