"How About a Vaccine?"
Daring to imagine a world without dementia
I was having coffee with a researcher a few months ago when I asked what felt like a routine question. What’s actually moving in dementia research right now? I expected the standard update: incremental progress, promising trials, cautious optimism. The kind of answer that reminds you how hard the problem is.
She paused, then looked at me across the table.
“How about a vaccine?”
Not a tool to slow it down. Not a protocol to help families manage the daily weight of it. A vaccine. To prevent it from taking hold in the first place.
I only realised afterwards that I’d gasped. Not loudly. But I’d felt it in my whole body. Because dementia already feels like a looming presence in so many lives, including mine. I’ve watched it move through people I love -- quietly at first, then with gathering force. The confusion, the repetition, the slow erasure of things that felt permanent. And somewhere along the way, I absorbed what most of us absorb: that this is simply what ageing does. That if you live long enough, this is part of the price.
“How about a vaccine?” was the first time that assumption cracked.
What we’ve made our peace with
The statistics have a way of cementing that resignation. More than 55 million people live with dementia worldwide, a figure the World Health Organisation projects will reach 139 million by 2050. In Australia, dementia overtook heart disease in 2024 to become the country’s leading cause of death overall, a position it has held for women since 2016. More than 17,500 Australians died from it last year alone. The number of dementia deaths here has increased by 160 per cent since 2006.
We absorb those numbers and build them quietly into our understanding of later life. We design systems to manage what we assume is coming. Memory care units. Dementia-friendly signage. Carer support programs. All necessary. All built on the same unstated premise: that decline is inevitable, and the best we can do is soften the landing.
That premise shapes everything. It shapes the services we fund, the conversations we avoid and the plans we never quite get around to making. It shapes the way families watch their parents age and say nothing, because what is there to say when the outcome feels fixed?
The science that changes the question
It is not fixed. That is what the research coming out of the past two years is beginning to make clear.
A 2024 study published in Nature Medicine found that a widely available shingles vaccine already in routine use showed a significant association with reduced dementia risk. A follow-up study in 2025, tracking more than 436,000 people, found an 18 per cent reduction in dementia diagnoses over 18 months among those who had received it. Researchers believe the mechanism may involve reducing infections that trigger brain inflammation, or a broader effect on immune function. The precise pathway is still being mapped. The association itself is not in doubt.
It does not stop there. A growing body of evidence is pointing toward associations between several routine adult vaccines and meaningful reductions in dementia risk, with some observational studies showing figures between 25 and 40 per cent. The picture forming is one where the immune system plays a far larger role in cognitive decline than anyone had previously understood. And where dementia, in at least some of its forms, may be influenced by factors we can actually act on.
That is not a small thing.
What happens when you stop assuming
In their 2025 book Abundance, Ezra Klein and Derek Thompson use Operation Warp Speed as an example of what becomes possible when you strip away the assumption that something cannot move quickly. The COVID vaccine was supposed to take years. It took ten months, because there was a single clear goal and the institutional friction was removed. Klein and Thompson argue this logic could be applied to almost any problem we have decided to treat as intractable.
Dementia is that problem. And for decades we have been so focused on managing its consequences that we forgot to seriously interrogate its causes.
That shift in framing matters beyond policy and research funding. If dementia is not inevitable, if it is at least partly a condition shaped by immune function, lifestyle and deliberate choices made decades before any symptom appears, then the question of how we plan our later lives changes shape entirely. You stop designing around loss. You start designing around protection. You stop asking how you will cope if your mind goes, and you start asking what you are doing now to protect it.
That is a different question. It opens different answers.
Design accordingly
This is not a call to wait for science to finish the work. It is a call to stop planning as though the outcome is already written.
Ask your GP about the vaccines available to you and whether you are eligible. Beyond that, treat your cognitive future as something you have genuine agency over. Move regularly. Protect your sleep. Stay connected to people in ways that require your brain to work. None of these are guarantees. But they are not nothing, and the evidence that they matter is no longer fringe.
Dementia is not inevitable. That sentence felt unearnable a few years ago. Today it does not.
Design accordingly.