For much of the past century, cognitive decline has been accepted as one of life’s unavoidable certainties — as natural and irreversible as grey hair or failing eyesight. The dominant cultural narrative told us that our brains peak in early adulthood and slowly, inexorably, deteriorate from there. Dementia, we were told, was largely a matter of fate. Yet a quiet revolution has been unfolding in neuroscience, one that challenges this assumption at its foundations. Longitudinal studies, emerging research on neuroplasticity, and a growing body of evidence on the preventability of dementia are converging on a startling conclusion: how our brains age is far more within our control than we ever imagined — and the primary levers are not pharmaceuticals or expensive interventions, but the ordinary choices we make about how we use our minds every day.
In this interview, I speak to Dr. Tommy Wood, Associate Professor of Pediatrics and Neuroscience at the University of Washington, where his laboratory focuses on brain health across the entire lifespan — from therapies for newborn brain injury to the factors that determine long-term cognitive function and dementia risk. He holds a degree in biochemistry from the University of Cambridge, a medical degree from the University of Oxford, and a PhD in Physiology and Neuroscience from the University of Oslo. Alongside his academic work, Dr. Wood serves as head scientist for Motorsport at Hintsa Performance, overseeing health and performance programmes for multiple Formula 1 drivers. He is also Head of Research for the dementia prevention charity Food for the Brain, and co-host of The Better Brain Fitness Podcast. His new book, The Stimulated Mind: Future-Proof Your Brain from Dementia and Stay Sharp at Any Age, presents his groundbreaking 3-S model — Stimulus, Supply, Support — as a practical, science-backed blueprint for cognitive longevity at every stage of life.
Q: You have a central claim that cognitive decline isn’t inevitable — a real challenge to the dominant cultural story about ageing. What led you to this way of thinking, and why is it so significant when we think about brain health?
[Dr. Tommy Wood]: There are probably a few things that came together. One of the primary things I research in my lab is brain injury in babies. When you look at brain development — and actually the process of biological development broadly — you see that your development is really driven by refining function in response to environmental inputs. The human brain stops growing new neurons in most regions. It continues a little in some areas of the brain throughout life, but most new neuron growth stops when you’re a toddler or a young child. After that, what you’re doing is refining connections based on inputs from the environment. Even children born with very significant brain injuries can develop remarkably well depending on the environment they go home to — that has a massive effect on how well their brains function later in life.
One of the potential theories of ageing is that ageing is just a continuation of these developmental processes. If you think the stimuli your brain receives are the primary driver of how that brain develops — which we have good evidence for in children — then what happens as we get older is that the brain is still waiting for those inputs. When those inputs are removed, it starts to prune function and structure, because those functions aren’t needed anymore. It’s still that same process — we just call it ageing. And it happens because we’ve removed physical activity, cognitive stimulus, and social connection. The brain responds accordingly.
I’ve been deeply interested in longevity for a long time, and you consistently see that the main things which prevent death or slow ageing are stimulus-driven — they’re about the maintenance of function. On top of that, there’s been a growing appreciation that a significant proportion of dementias are preventable. If dementia is preventable, it means we’re changing the trajectory of cognitive decline — which means that trajectory isn’t inevitable. And then the final piece was looking into research done here at the University of Washington. Back in the 1950s, they began a study called the Seattle Longitudinal Study, run by a researcher called Warner Schaie. They measured cognitive function in the same people every seven years over several decades — one of the first studies to really do that, to track the same individuals over long periods. What they found was that the majority of people — above 50% — maintained cognitive function from their 50s into their 80s. We knew this more than fifty years ago. Data from that study were actually used to raise the retirement age in the United States, because unlike what Sir William Osler told us at the beginning of the 20th century — that at 60 the adult human is essentially useless and should be put out to pasture — we learned, even then, that that wasn’t the case. So I think all of these ideas and different areas of research came together to build this picture that we have a significant ability to change our cognitive trajectory. But first, we need to believe it’s possible. And second, we need to engage in the things that allow it to happen.
Q: Was that the genesis of the 3-S model — Stimulus, Supply, Support? It would be good to really understand what those three pillars are and how they practically play a role in our lives, because I think that sets a solid platform for discussing some of the specific nuances.
[Dr. Tommy Wood]: The 3-S model actually required a couple of additional threads from my own experience. One is that when I was in medical school, I encountered some engineering-type principles — a way that engineers solve complex problems — specifically something called systems analysis, which is essentially a way of building a large, interconnected picture of how many things within a complex system interact with each other. When we were doing that, we were applying it to a different neurological condition — multiple sclerosis — but one of the ultimate goals was to ask: what are the common things that really seem to underpin how everything works within the system? Applying this to cognitive function and cognitive decline, I saw these core areas emerge.
But some of it is also grounded in my experience as an athlete and a coach. When you think about building physical function — be that strength, muscle mass, or cardiovascular fitness — we know the primary driver is stimulus: the training you apply to the body. But you can enhance how you respond to that stimulus by making sure you have adequate nutrition, that you’re resting and recovering properly, and so on. In sports science, this is often called the stimulus-recovery-adaptation model. The 3-S model isn’t quite the same, but the principles are similar. If we want to build or maintain function, we need to apply a stimulus. And then, as much as we can, we need to provide the environment that allows us to best adapt to that stimulus. That’s where the different components of the 3-S model come together.
Q: I think there are two aspects to this: one is about ageing, but the other is about leading high-performance lives — and this is where your work with athletes has been so interesting. Many readers of Thought Economics are in C-suite or founder roles, in high-performance careers. Can this model also help them ensure their brain health is optimised — whether around headroom management or achieving the right balance of the three pillars?
[Dr. Tommy Wood]: Yes, absolutely. One of the reasons I felt confident enough to write this book is that regardless of which situation we’re thinking about — building cognitive function early in life, maintaining or enhancing performance in midlife, operating at the elite levels of cognition in knowledge workers or what I call cognitive athletes, or preventing dementia later in life — the same factors appear again and again, in the same way. That tells us something about the fundamental needs of the brain to underpin performance.
When you apply this in an executive context, you probably need a slight shift in focus — which of the pillars comes to the foreground. A near-perfect example is the Formula 1 drivers I work with. Formula 1 drivers get enormous stimulus. They are driving the most complex cars in the world as fast as anyone can physically drive. They also have to engage intensely on the engineering side. There’s simply so much coming at them from the stimulus direction. So when I talk to Formula 1 drivers, the thing they know they need — almost instinctively — is more recovery. That means we’re really thinking about the Support bucket of the 3-S model. I do spend time thinking with them about nutrition and other areas within the Supply bucket too, but support is where the focus lands.
I think we see something very similar in executives. They’re doing complex problem-solving, a great deal of social communication and interaction, and very varied, stimulating work. So really, where the focus for them needs to be is in the other two pillars. For a lot of them, the nature of the lives they lead may mean they’re starting to experience the early markers of metabolic disease — elevated blood pressure, disrupted blood sugar. So there may be work to do in the Supply bucket. Or they’re simply not giving themselves the time to truly adapt and recover from all the work they’re doing — they’re overstimulated, chronically stressed, not sleeping enough. That means we really have to focus on the Support bucket. In that world, people are generally getting enough stimulus. It’s about thinking: how am I getting the most out of that? And as we transition later into life, maintaining stimulus becomes much more important, because that’s the thing that tends to drop off most sharply.
Q: Are there things that all of us — regardless of where we are — should be doing to improve our brain health? In my own life, I know the Support element was chronically missing. I was eating well, training well, getting bags of stimulus running businesses — but I wasn’t giving my brain downtime. From your research, what are the two or three things that all of us should be doing day-to-day to genuinely optimise brain health?
[Dr. Tommy Wood]: In that particular scenario — where you’re maintaining good physical health, training well, no elevated blood pressure or blood sugar, eating a high-quality diet — where you really need to focus is the Support bucket. What we consistently see, even among high performers, is that the thing they don’t get enough of is sleep. And they don’t get enough sleep because they don’t give themselves enough sleep opportunity — a way of saying they don’t spend enough time in bed. Because if you don’t spend enough time in bed, you can’t get enough sleep. That’s usually where I start.
From there, it’s about thinking: how can you create a routine that allows for restful sleep? Protocols like stopping work at a certain time in the evening and finding a way to wind down. And you generally have to do this step by step — I can’t go to someone sleeping five hours a night and say ‘you need to sleep eight hours, starting now.’ It’s never going to happen. But adding 15 or 30 minutes at a time, and finding a way to gradually shift that threshold downward — that’s achievable.
Some of this is about psychological tools and techniques. Mental offloading — writing down to-do lists and worries before bed — has solid evidence behind it. Writing things down or completing to-do lists in the hour before bed clears the cognitive load that keeps people lying awake. Slow-paced breathing at bedtime has been shown to significantly reduce sleep onset time in people with insomnia. So it becomes a combination of realising you need more rest and recovery, and then finding the specific mechanisms that work for you.
I can make the case for more rest on many different fronts. If you don’t sleep enough, you’re less empathetic towards your employees. You’re less able to maintain meaningful relationships — and that can affect your business over the long term. The situation that’s emerged around René Redzepi and Noma — his treatment of staff coming to light after two decades — is in part what happens when someone operates for years in a state of chronic stress and insufficient sleep. It changes how they relate to other people in ways that eventually have serious consequences. So it’s about finding the right hook: it could be a personal cognitive function concern, a social connection and empathy concern, or the growing awareness of future dementia risk. And then finding a way to let that rest time expand. Some of it you can also do during the day — structured breaks, even just a few minutes, have strong evidence for rapidly reversing mental fatigue and restoring the capacity for difficult thinking.
Q: Why is it so hard to persuade people to make these changes? I think about myself a few years ago — with my last business — and it would have been a mountain to persuade me to do it. And you’re working with Formula 1 drivers, athletes, people at the absolute peak of performance. Persuading an F1 driver to get a few extra hours of sleep and step back from constant thinking about their performance — I’m sure that’s no small thing. How do you get through to them?
[Dr. Tommy Wood]: You’re right. And I’ve definitely experienced this both with drivers and with health coaching clients in business. If someone is performing at a very high level and I say ‘you need to do something radically different to improve your brain health’, the response can be: ‘I’ve already won world championships, so I think I know what I’m doing.’ I don’t care if you tell me I’m wrong. I appreciate that this is real. And for some people, honestly, giving them information simply doesn’t change their behaviour. I can say it as much as I want — it’s not going to get through.
Most people will not change their behaviour until they directly experience a negative effect of their current behaviour. That could be noticing changes in their cognitive sharpness, changes in how they interact with other people, or changes in their physical health. Because even if you exercise a lot and eat well, if you’re chronically sleep-deprived, your blood pressure will go up and your blood sugar will go up — and you will start to see real consequences. The behaviour-change problem hasn’t been solved yet. It really hasn’t. It still ultimately requires someone to arrive at their own core reason for wanting to change, and then engage with the information from that place.
Q: Another part of your work that’s utterly fascinating is this notion that our entire understanding of dementia and decline is being fundamentally rewritten. Are we now at a point where you think stimulus could be a more powerful lever for addressing cognitive decline than what we currently consider to be disease-based treatment?
[Dr. Tommy Wood]: Yes — and I think the risk has both evolved historically and is shifting again. Historically, I think we had a natural arc in how we used our brains across the adult lifespan. The higher your level of educational attainment — the longer you spend as a professional learner — the higher and later your peak of cognitive function. And if you do get dementia, the later it occurs, because you’ve started from a higher baseline. If you have greater reserve, you can lose more before the effects become apparent.
When we leave education and go to work, most people settle into doing the same things again and again. We’ve stopped continuing to stimulate our brains in meaningfully novel ways. In certain jobs that’s not the case — in my job I do something different every day — but across the general population, particularly in more repetitive work, that pattern holds. Because you’ve removed the primary driver — complex, varied stimuli to the brain — function starts to decline. We call it ageing, but it’s really the brain responding to a change in its environment.
Then we retire, and we remove stimulus almost entirely. Whatever cognitive and social scaffolding work provided disappears, and we often see a sharp drop in cognitive function. The hypothesis is that this was partly driven by societal expectation — what’s called stereotype embodiment theory. We start to embody the cultural stereotype of ageing, and it becomes a self-fulfilling prophecy. If you believe you’re going to lose function as you get older, you stop doing the things that maintain it, or you simply accept the losses. ‘Oh, it’s ageing, this is just how it works.’
What concerns me now is a potentially larger threat: AI and other tools that allow us to let technology do all of our thinking. The research here is very nascent — and it will evolve rapidly — but it’s already clear that when you ask technology to do the thinking for you, your brain doesn’t engage the networks involved in that task. You therefore won’t maintain that function, and you tend to produce lower-quality, more derivative work. If we offload all of our critical and demanding cognitive work to AI, we may actually accelerate that decline because we’re no longer using our brains in the ways that maintain them.
The alternative — and it’s still very much available — is to do the hard cognitive work yourself, and then use these tools to build on it. Write your own presentation, then ask Claude: ‘What did I miss? What could I add? What could I do differently?’ Then integrate those thoughts yourself. You’ve done the demanding cognitive work, engaged the relevant networks, produced something better — and extended your capacity rather than eroding it. A lot of it comes down to how we choose to engage with these tools. But the risk of no thinking being required at all — while still getting work done — is real.
The way I think about this: we changed the modern food environment to the point where we had to invent diets in order to stay healthy. We changed the modern built environment so that we no longer needed to move, and so we had to invent exercise. We may now be changing the modern cognitive environment to the point where we’re going to have to deliberately invent ways to stimulate our brains — just to maintain function. I think that’s the next frontier we’re going to have to navigate.
Q: As a kind of civilisational roundup — through the whole of the 20th century, we largely accepted cognitive decline as a given. From your research, we can now say there are things we can do as a society around stimulation. But what are the truly foundational changes we need to make to ensure that brain health, as a civilisation, is better — for everyone? It seems that naturally we make shortcuts, those shortcuts have consequences, and then we have to retreat and correct. Surely there must be a better path now?
[Dr. Tommy Wood]: I think the main thing that needs to change is simply having people understand that cognitive trajectory is changeable — and that understanding then creates an environment which promotes and supports it at a societal level. We’re on a similar path with this to where we were with exercise a generation ago. Everybody knows now that you need to exercise for health. A lot of people still don’t do it — partly because some don’t enjoy it, don’t know what it should involve, or carry this idea that exercise has to be hard, boring, sweaty, and uncomfortable. So there’s education to be done, because exercise that benefits health doesn’t have to look like that. And we also need to improve access: not everyone has the time or means for a gym membership, and even when they get to the gym, do they know what to do?
I think we’re at that same early stage now with cognitive stimulus. First, people need to really understand that how we use our brains is the primary determinant of how those brains function. Then the next step is figuring out what that looks like in practice — and helping people realise it can look very different from person to person. It could be video games, creative arts, dancing, learning a language, playing music. The key is lifelong engagement with novel, cognitively stimulating activities, whatever form those take. And then it’s about making those things accessible — similar to making it possible for anyone who wants a gym membership to have one. But also just helping people understand that it can be a huge variety of things, whatever it is they genuinely enjoy.
As we move towards the later stages of life, the UK is apparently moving towards appointing a dementia tsar, and there’s growing recognition of the need for systemic reform. But I think the most urgent institutional change is this: when someone begins to show cognitive decline, the current instinct is to do the opposite of what’s needed. We place them in a small room in a care home, with minimal social contact and little stimulation. What the brain needs at that point, more than ever, is stimulus, support, and social connection — and right now we do precisely the opposite. That represents a complete overhaul of how we approach individuals as they enter that phase of life.
There’s also a lot that can be done at the individual level — similar to how exercise works now. You and I can think about what cognitive stimuli we’re getting, how we’ll maintain those, what new skills we’re going to learn. But we also need to take care of the people at greater risk: those who may not know about this, don’t know how to implement it, or can’t access it. That means making things accessible — dance classes, social activities, cognitive engagement programmes. I’m also very interested in cognitive training in virtual reality — multi-sensory, rich, genuinely challenging environments that could eventually be delivered at home at scale as headset costs fall. That kind of accessible, engaging cognitive stimulus, available to people regardless of income or mobility, could represent a real shift in how we protect brain health across the population. There’s a lot to be done — those are all the different pieces I think we’d need to put together.
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Dr. Tommy Wood’s book The Stimulated Mind: Future-Proof Your Brain from Dementia and Stay Sharp at Any Age is published on 24 March 2026.