New hope may have been raised about potential treatments for dementia after a powerful response to an NHS shingles vaccine.
The Shingrix shingles vaccine given to people on the NHS is linked to at least a 17% drop in dementia diagnoses in the six years after vaccination than the previously used Zostavax jab, according to a new study.
Researchers say it amounts to 164 or more additional days lived without dementia.
Here are some thoughts from the Oxford University researchers behind the study who stress that more investigation is needed to confirm the value of the vaccine and why it works so well.
Dr Maxime Taquet, academic clinical lecturer in the department of psychiatry at Oxford, said “that is our interpretation”, adding that the greater difference has been spotted in the time at which people “receive a diagnosis of dementia and, therefore, more time without a diagnosis rather than preventing diagnosis all together”.
Paul Harrison, a professor of psychiatry at Oxford, added: “Even if it is a delay of 164 days for example, in the public health level, that would not be a trivial finding whatsoever.”
– Could it lead to a potential treatment for dementia?
Prof Harrison said: “Herpes viruses might be one of the many factors that can promote dementia or could be a risk factor for dementia and therefore a vaccine that is stopping you having reactivation of this virus might be delaying whatever that process is that is leading you to be at risk of dementia in the coming years.
“The other possibility is that this vaccine, like many vaccines, has got adjuvants in it (which has) got chemicals designed to make sure your body reacts to the vaccine in a strong enough way to get the protection it seeks.
“The Shingrix vaccine has got different and perhaps more potent chemical adjuvants in it than the previous vaccine.
Experts said more study is needed.
– Do other vaccines also have this potential effect?
Prof Harrison said there is “some evidence some other vaccines against different infections might also have benefits”.
“The Shingrix vaccine looks better than the various other vaccines against which it has been compared,” he added.
On whether vaccination in general has any protective effects against dementia risk, he said: “I think that is still an open question but it would look at the moment as if Shingrix, for some reason, may be more valuable in this regard than other vaccines.”
Prof Harrison said the vaccine was originally licensed where the doses were given two months apart.
He said: In the NHS, I think partly for pragmatic reasons, the second dose is meant to be given six to 12 months apart.
“So whether that is better or worse or has any impact on the sort of data we are looking at today, we don’t know.
“Similarly, whether any beneficial effects associated with the vaccine are greater or lesser depending on the age at which the first dose is given is again something we don’t know about.”
He described it as “a really important question” because one could imagine “there might be greater benefits in people receiving the vaccine younger – on the other hand it might not be like that”.
Prof Harrison said: “If you are asking if one should be doing a randomised trial of giving this particular vaccine and seeing if it reduces the risk of onset dementia – that is a really difficult question.
“It has now been rolled out to everybody because its benefits against shingles are so clear, it would be difficult ethically as well as practically to design a trial in which some people would be randomised and not be given it.
“I think it may be an area in which one needs more data like ours from other data sets that all start telling the same story so that it almost become implausible that there is not a causal connection.
“Then, I guess, it would be up to public policy makers to decide would that be enough to even suggest that this particular vaccine might be something in the armoury of reducing the risk of dementia?”
– What are the immediate implications for clinical practice now from these findings?
Prof Harrison said it would be interesting to see if “after hearing of these findings whether the public choose to increase the uptake of the Shingrix vaccine when offered it by the NHS”.
He added: “I certainly would not recommend that people should start demanding the vaccine just because they think it could reduce the risk of dementia.”
