Do some vaccinations really reduce dementia risk?

There is increasing evidence that vaccines can help significantly in the prevention of dementia in ways that are still unclear to the medical community.
 
Associate Professor Michael Woodward is Director of Dementia Research at Melbourne’s Austin Health, and told newsGP he was surprised when he first saw research linking shingles vaccines to a reduced risk of dementia.
 
‘I did not expect vaccination would prevent dementia,’ he said.
 
‘I thought it was an aberration.’
 
Research from Wales, as referenced by Associate Professor Woodward, found people who were exposed to the shingles vaccine were at lower risk of being diagnosed with dementia.
 
Separate research that analysed thousands of studies found vaccinations were associated with a 35% lower risk of dementia.
 
‘Individuals with more full vaccination types and more annual influenza vaccinations were less likely to develop dementia,’ it states.
 
Yet another study has linked a 42% lower risk for dementia following adult tetanus, diphtheria, and pertussis (Tdap) vaccination.
 
Now the question is, Associate Professor Woodward says, why would this be?
 
‘We don’t know,’ he said.
 
‘There is some evidence that certain viruses might increase your risk of dementia, and therefore an antiviral vaccine might reduce it, or it may be that the vaccine is promoting off target effects.’
 
There is ample evidence, but no study so far has been able to determine exactly why this is.
 
‘The exact biological mechanism underlying the association between vaccination and reduced risk of dementia is unclear,’ one study states.
 
Regardless of the reason, Associate Professor Woodward says it is something GPs need to be aware of and communicate to their patients.
 
‘You’re telling patients, “have your shingles vaccine because shingles is horrible”, “have your RSV vaccine because RSV is horrible”, but you should actually say, “oh, and by the way, the disease you dread the most, you’re also reducing your risk of that,’ he said.
 
‘There’s now enough, I think, to actually say that.’
 
Professor Dimity Pond, a GP with a special interest in aged care, thinks these results make sense even if the reason why is unclear.
 
‘We do know that some diseases, including vaccine preventable ones like shingles, can predispose people to dementia,’ she told newsGP.
 
‘The jury is still out on which vaccines, and how well they work to prevent dementia.
 
‘However, vaccination is consistent with good public health policy and this possibility is another reason to promote it.’
 
Associate Professor Woodward says the same rigor needs to be applied in making sure older people are fully vaccinated that it is for children.
 
‘We don’t accept kids getting to the age of five without having all their vaccines … by the same token, we shouldn’t be allowing people in their 60s and 70s to be missing out on vaccines,’ he said.
 
‘Because not only can you prevent vaccine preventable diseases, but you can possibly prevent other diseases such as dementia.’
 
Log in below to join the conversation.

Alzheimer’s disease dementia dementia risk preventative health vaccination