July 25, 2024

expert reaction to study suggesting new shingles vaccine associated with lower risk of dementia

A study published in Nature Medicine looks at the shingles vaccine and risk of dementia. 

Prof Tara Spires-Jones, FMedSci, President of the British Neuroscience Association, Group Leader in the UK Dementia Research Institute, Director of the Centre for Discovery Brain Sciences at the University of Edinburgh, said:

“This study by Taquet and colleagues reports that a relatively new shingles vaccine is associated with a lower risk of developing dementia in the 6 years post-vaccination compared to people vaccinated with the old shingles vaccine or those vaccinated against other diseases.  The study is very well-conducted and adds to previous data indicating that vaccination against shingles is associated with lower dementia risk.  More research is needed in future to determine why this vaccine is associated with lower dementia risk.” 

Prof Rob Howard, Professor of Old Age Psychiatry, University College London (UCL), said:

“Although previous studies have suggested immunisation against herpes viruses might protect against dementia, particularly in women, this took advantage of a change in vaccine type to overcome the many confounding variables that may have provided alternative explanations. The next question is how does vaccination exert this dementia protection effect? Is it through suppression of virus or is the induced immune response targeting a step in the molecular pathology of Alzheimer’s disease?”

Prof Andrew Doig, Professor of Biochemistry, University of Manchester, said:

“In the USA, over 65s are routinely vaccinated against the herpes zoster virus to prevent the onset of shingles. This virus is also the cause of chicken pox. In 2017, health care providers switched from a live vaccine called Zostavax to a more effective recombinant version called Shingrix.

“This study looks at data from just over 100,000 people who were given the live vaccine from 2014-2017 and the same number who had the recombinant vaccine from 2017-202. All were over 65. Apart from the type of vaccine and the date they received it, the groups were very similar. All were followed up for four to six years after the vaccination to see how many were diagnosed with dementia (mostly Alzheimer’s Disease) in that time.

“This study is straightforward, the number of patients involved is large and other factors that might affect the results have been ruled out, so the results are convincing.

“The results were simple and clear: There was already some evidence that the old live vaccine was able to reduce the risk of Alzheimer’s Disease. This work shows that the new recombinant vaccine is even more effective, decreasing the likelihood of being diagnosed with dementia, if the new vaccine is used rather than the old one. Another way to look at it is that the age of onset of dementia is delayed by an average of 164 days, with a larger effect in women than men. This is a significant result, comparable in effectiveness to the recent antibody drugs for Alzheimer’s Disease. Administering the recombinant shingles vaccine could well be a simple and cheap way to lower the risk of Alzheimer’s Disease.

“A link between infection with the herpes zoster virus and the onset of dementia has been suspected for some time, with Ruth Itzhaki from the University of Manchester first championing this idea, since the 1990s. As well as vaccines, a trial of the anti-viral drug Valacyclovir against Alzheimer’s Disease is currently underway.

“Now, we need to run a clinical trial of the recombinant vaccine, comparing patients who receive the vaccine with those who get a placebo. This is the most reliable way to find out how well the vaccine works. We also need to see how many years the effect might last and whether we should vaccinate people at a younger age. We know that the path to Alzheimer’s Disease can start decades before any symptoms are apparent, so the vaccine might be even more effective if given to people in their 40s or 50s.

“Though the herpes zoster virus as a cause of Alzheimer’s Disease is looking more and more likely, we must bear in mind that any such link is not simple. Most people who are infected by the virus never get Alzheimer’s Disease, and some who get the new recombinant vaccine get Alzheimer’s Disease regardless. A vaccine is therefore unlikely to ever totally prevent Alzheimer’s Disease. Many other factors affect the likelihood of getting dementia, such as genetics, cardiovascular problems and head injuries. Nevertheless, tackling the herpes zoster virus does look to be a promising strategy towards defeating this horrible and costly disease, and one that should be vigorously pursued.”

Dr Sheona Scales, Director of Research at Alzheimer’s Research UK, said:

“Researchers from the UK have shown that people receiving the newer version of the shingles vaccine “Shingrix” appear to have a lower risk of dementia compared with those given “Zostavax”, an older shingles vaccine. The study was published in the scientific journal Nature Medicine.

“Previous studies have indicated that shingles vaccines like Zostavax might protect against dementia, but data have been limited. But newer ‘recombinant’ vaccines like Shingrix are now being given.

“This large, observational study used information from health records of over 200,000 people living in the US. They looked at records over several years, during which there was a switch from Zostavax to the newer Shingrix vaccine. This meant that the researchers were able to compare the risk of dementia in people who were given different versions of the vaccine.

“Over the course of 6 years, they found people receiving Shingrix vaccine had a 17% reduction (or a 164-day delay) in the onset of dementia compared to those given Zostavax. And while this effect was seen in both men and women, there was a slightly greater reduction in onset in women.

“Dementia isn’t an inevitable part of ageing; it’s caused by diseases like Alzheimer’s. So finding new ways to reduce people’s risk of developing these diseases is vital. This research, carried out in a large group of people, suggests that people given the “Shingrix” shingles vaccine might have a reduced risk of dementia. But it isn’t clear how the vaccine might be reducing risk, nor whether the vaccine causes a reduction in dementia risk directly, or whether there’s another factor at play. So it will be critical to study this apparent effect further.

“Here in the UK, a free shingles vaccine is available to people who turn 65, between 70 and 79, and who have a severely weakened immune system. Older shingles vaccines are now being replaced with Shingrix and anyone with questions about receiving the vaccine should speak to their doctor.

“While research into whether vaccines affect dementia risk continues, people should be aware that there are other factors that have definitively been linked to an increased dementia risk. These include things like smoking, high blood pressure and excessive alcohol consumption. Our Think Brain Health campaign outlines the steps you can take to protect your brain health and lower your risk of dementia. Find out more at www.thinkbrainhealth.org.uk”

‘The recombinant shingles vaccine is associated with lower risk of dementia’ by Maxime Taquet et al. was be published in Nature Medicine at 16:00 UK Time on Thursday 25 July 2024.

DOI: 10.1038/s41591-024-03201-5(2024).

Declared interests

Prof Tara Spires-Jones: I have no conflicts with this study. For unrelated research and consulting, I have received grants or honoraria from Scottish Brain Sciences, AbbVie, Ono, Sanofi, Jay Therapeutics, UK Dementia Research Institute, Race Against Dementia, the UK Medical Research Council, Alzheimer’s Society, and the US Foundation for the National Institutes of Health.

Prof Rob Howard: No conflicts.

Prof Andrew Doig: Andrew Doig is a founder, director and consultant for PharmaKure Ltd., which works on Alzheimer’s drugs and diagnostics, though not on viruses. He has co-written a review on Viral Involvement in Alzheimer’s Disease.

For all other experts, no response to our request for DOIs was received.