Dr. Tommy Wood on the neuroscience of brain stimulation — why the brain atrophies the same way muscle does, and what it takes to prevent it.
6 min read · Based on Dr. Tommy Wood on the Joe Rogan Experience
TL;DR
Between 45 and 70% of dementias are preventable. The most important driver of cognitive decline — outside of acute disease — is not aging. It’s the cessation of cognitively challenging activity. The brain follows the same use-it-or-lose-it logic as every other tissue in the body. Dr. Tommy Wood, neuroscientist and head scientist for a Formula 1 performance organisation, breaks down exactly what the brain needs to maintain function — and why most people have stopped providing it long before they notice the consequences.
“We’ve embodied this idea that as you get older you will decline. As a result, you stop engaging in all the things that would prevent that decline. It becomes a self-fulfilling prophecy.”
Dr. Tommy Wood is a physician and neuroscientist whose work spans newborn brain injury, traumatic brain injury, cognitive ageing, and elite athletic performance — including work with Formula 1 drivers through Hintsa Performance. His book The Stimulated Mind synthesises 2,000 research papers into a practical framework for maintaining and improving cognitive function across a lifetime. The core finding is less complicated than most people expect.
1. Between 45 and 70% of dementias are preventable — and most of those are lifestyle-driven.
Dementia is not a single disease. Alzheimer’s accounts for 60 to 80% of cases, vascular dementia for another 10 to 20%. Together those two categories represent roughly 70 to 90% of all dementias — and both are directly tied to lifestyle and environment.
The genetic picture is more nuanced than most people realise. The APOE4 gene variant, which increases Alzheimer’s risk by two to six times with one copy and six to 20 times with two copies, functions as a risk multiplier rather than a verdict. What that means practically: the lifestyle factors that increase dementia risk — physical inactivity, poor diet quality, excessive alcohol — have an amplified negative effect in APOE4 carriers. Conversely, addressing those factors delivers amplified benefit. Genetics sets the sensitivity of the system. Lifestyle determines what you do with it.
Family history of dementia is a risk factor, but a large component of that risk is shared environment and shared behaviour rather than pure genetics. Children who eat, sleep, and move like their parents often have similar health trajectories for that reason.
2. The brain atrophies on the same principle as every other tissue. What you don’t use, you lose.
This is the core thesis of Wood’s book and it is less metaphorical than it sounds. The function of any tissue — muscle, bone, liver, immune system — is dependent on the stimulus applied to it. Remove the stimulus and the tissue optimises downward. The brain is not an exception.
The modern paradox is that people are simultaneously overstimulated and understimulated. The volume of information coming in has never been higher. The quality of cognitive demand — the proportion of that input requiring original thought, creative synthesis, problem solving, or decision-making — has never been lower. Consuming content is not the same as processing it. Scrolling is not thinking.
Wood makes a specific point about AI tools that is worth sitting with: a study at MIT found that when students used language models to write essays, brain activity in the networks associated with the task decreased significantly and retention of the material was substantially lower. The output improved but the learner did not. The productive use of these tools — attempting the task fully first, then using AI to identify gaps — produces a different result. The brain has to be in the loop for the learning to happen.
The OMNIFIT angle: This is the scientific foundation for why Cognitive training is a dimension in OMNIFIT Daily, not an optional add-on. The Cognitive block — deep work, language learning, memory drills, focused reading — exists because these are the activities that preserve the brain networks most vulnerable to age-related decline. Passive consumption does not substitute.
3. Neuroplasticity is driven by failure, not success.
This finding is counterintuitive enough to be worth stating clearly. The brain is a prediction machine. It is constantly generating predictions about what will happen next based on current inputs and prior experience. When those predictions are correct, no significant remodelling occurs. When they are wrong — when there is a meaningful gap between expectation and reality — the brain diverts resources to close that gap. That diversion is neuroplasticity. That is how new connections form and existing connections strengthen.
The uncomfortable feeling of learning something new and being bad at it is not an obstacle to neuroplasticity. It is the mechanism of neuroplasticity. The frustration is the signal that the brain is working.
This has an important practical implication: shallow engagement with many things produces less cognitive benefit than genuine struggle with fewer things. Wood references studies on tango dancers, painters, and video game players showing that the brain benefits of skill acquisition are most pronounced at expert level — but the steepest learning curve, and therefore the most neuroplastic activity, is at the beginning. The recommendation is to find one or two skills that genuinely engage you and pursue them long enough to develop real competence, not to collect a rotating portfolio of new experiences you never deepen.
4. The headroom concept: you need far more capacity than you currently use.
Wood introduces a concept he calls headroom — the gap between your day-to-day cognitive requirement and your maximum cognitive capacity. The analogy is physical: your legs need to be strong enough to get you off the toilet, but your maximum capacity is your best back squat. The gap between those two is your headroom.
Headroom matters because life is not lived at the average. Sleep deprivation, illness, stress, injury, grief — all of these temporarily reduce your functional cognitive capacity. If you have built substantial headroom through years of cognitively demanding activity, these events reduce your performance from a high base and you remain functional. If your headroom is thin — if your daily function is already close to your maximum capacity — the same stressors push you into meaningful impairment.
Building headroom requires consistently operating above your current cognitive comfort level. The same brain that stops developing muscle mass when training stops will stop maintaining neural networks when cognitive challenge stops. The challenge has to be ongoing.
5. Cognitive decline is not the norm. It’s what happens when people stop engaging.
The Seattle Longitudinal Study, run by Warner Schaie, tracked the same individuals every seven years across several decades — from their 20s through to over 100 years old. The finding that should be far more widely known: more than 50% of people maintain the same level of cognitive function into their 50s, 60s, 70s, and 80s.
The population-level data showing average cognitive decline with age is real, but it is a statistical artefact of aggregating a population where a large proportion has already stopped engaging in the activities that maintain cognitive function. When you track individuals rather than cross-sections, stable function across decades is the norm, not the exception.
The practical implication is significant. The belief that cognitive decline is inevitable in older age — a belief most people hold — causes people to stop engaging in the activities that would prevent it. It becomes a self-fulfilling prophecy. People say they are too old to learn a new skill, too old to engage in demanding work, too old to exercise at meaningful intensity. Each of those decisions accelerates the very process they believe is inevitable.
6. The 3S model: Stimulus, Supply, Support.
Wood’s framework for understanding how all the relevant variables interact is worth understanding because it explains why no single intervention is sufficient — and why improving any one component tends to improve the others.
Stimulus is the cognitive challenge itself. Novel, difficult, often creative activities that require your brain to form and strengthen connections. This is the dimension most people in middle age and beyond have allowed to atrophy.
Supply is what the brain needs to respond to that stimulus. Primarily blood flow — when a brain network is activated, the neurons and astrocytes there demand more oxygen and metabolic substrate, and the blood vessels must dilate to deliver it. This is why cardiovascular health and metabolic health are so directly tied to cognitive function. High blood pressure and elevated blood sugar are two of the strongest risk factors for dementia, not because they affect mood or energy but because they impair this supply mechanism. Specific nutrients — omega-3s, vitamin D, iron, magnesium, B vitamins — also have defined roles in brain function where deficiency directly increases cognitive decline risk.
Support is what enables the brain to consolidate, adapt, and repair in response to stimulation. Sleep is the primary support mechanism — the brain’s glymphatic clearance system, the consolidation of new memories, the restoration of attentional capacity all happen during sleep. Chronic stress, excessive alcohol, air pollution, and smoking all impair the support function. So does insufficient production of BDNF — brain-derived neurotrophic factor — which exercise is one of the most effective known ways to stimulate.
The interconnection of these three categories means that improving any one tends to create positive cascades across the others. Sleeping better reduces inflammation and improves blood pressure, making the following day’s Supply better. Exercising more stimulates BDNF and improves cardiovascular fitness, making both Stimulus and Supply more effective. Engaging in a demanding cognitive skill drives deeper sleep, completing the cycle.
One thing to do this week
Identify something you have always wanted to learn and have not started — a language, an instrument, a movement skill, a creative practice. Commit to 20 minutes of genuine struggle with it four times this week. Not consuming content about it. Not planning to do it. Doing it, badly, and staying with the frustration. That frustration is the mechanism. It is not a sign you are doing it wrong.