Neuroscience Confirms: The Secret To Looking 40 In Your 60s

Dr. Wood references a study that randomized participants into a control group, a jogging group (zone 2-ish), and a high-intensity interval training group doing the Norwegian 4x4 protocol three times a week for six months. The interval group showed significantly greater improvements in hippocampal structure and function compared to the jogging group, and these benefits were maintained for five years. The primary physiological drive is lactate signaling, which easily enters the brain and switches on BDNF production. While any exercise is better than none, and starting with something like brisk walking is fine for the previously sedentary, once a basic fitness level is achieved, shifting to intensity-dependent training yields far greater cognitive rewards. This directly challenges the common longevity advice to spend many hours in zone 2, which Dr. Wood considers far less efficient for brain outcomes. He also emphasizes that this shouldn't be the sole exercise; resistance training and coordinative sports offer additional, non-overlapping brain benefits.

Dr. Wood points to studies where older adults following a very basic resistance program twice a week saw improvements in white matter structure and cognitive functions like executive function and processing speed. The benefit does not require extremely heavy weights; as long as you approach muscular failure—whether through heavier loads and fewer reps or lighter loads and more reps—the mechanical tension stimulates IGF-1 production, which maintains white matter integrity. He also notes that blood flow restriction training can be an alternative for those who lack heavy weights or prefer joint-friendly methods. Additionally, loading the skeleton itself releases osteocalcin, which may have direct brain benefits. This protocol stands alone from aerobic or coordinative exercise, providing unique neural benefits, so it should be included in any brain health regimen.

Dr. Wood explains that when comparing two types of exercise with the same physical intensity—e.g., cycling versus dancing or badminton—the complex skill sport produces additional cognitive benefits. This is because it demands multi-sensory integration, rapid decision-making, and continuous adaptation, activating broader brain networks. He mentions that even adding a component of coordination to existing workouts—like using a balance board or doing Turkish get-ups—engages the vestibular system and provides extra protection against falls in old age. This principle aligns with the stimulus-first philosophy of the 3S model: the more complex the cognitive demand, the more robust the neuroplastic response.

Dr. Wood argues that in our current environment, many people spend an entire day without experiencing a single moment of true cognitive downtime, because smartphones and notifications provide a constant trickle of stimulation. This chronic low-grade input inhibits the brain's default mode network from engaging fully, preventing the integration and creative synthesis that come from boredom. He draws a parallel to physical recovery: just as muscles need rest periods to adapt, the brain needs idling periods to process stimuli. He considers this a major missing piece in modern brain health, contributing to shallow thinking and reduced resilience.

Dr. Wood cites evidence that creatine's cognitive benefits are most apparent in older individuals or those with already diminished cognitive function, likely because brain energy metabolism is compromised in these states and creatine acts as a phosphate shuttle to maintain ATP levels. He mentions a study in early Alzheimer's that showed benefit, another in postmenopausal women, and randomized trials supporting its use in treatment-resistant depression. For athletes, it may protect against subconcussive impacts over a season. While many supplements are promoted for brain health, Dr. Wood singles out creatine as the one other than vitamins that he explicitly recommends in his book. He takes it himself primarily for physical performance as a strongman but acknowledges the cognitive upside.

Dr. Wood uses Formula 1 as an extreme example: reaction time off the start line is a simple task that benefits from high arousal, but immediately after that, the driver must execute complex motor and decision-making skills navigating 20 other cars. If over-aroused by too much caffeine or stimulant anxiety, they may crash on the first corner. His team assesses each driver's optimal zone and uses tools to either increase arousal (light, cold, exercise, caffeine, tyrosine, creatine) or decrease it (breathwork, dark motorhomes, calming drills) to hit the peak performance point. This 'slider switch' approach is directly applicable to everyday life when we need to prepare for a demanding cognitive task—such as writing, coding, or a meeting—and we want to be neither sleepy nor jittery.

Building on the MIT study, Dr. Wood distinguishes between outsourcing thinking and using AI as a cognitive orthotic—a tool that extends your native capacity. The key is that the initial creation must come from your own neural circuits; this engages the process of focus, attention, and integration, which itself maintains the networks you're trying to preserve. Only after that personal effort do you engage the AI, and even then, it's not about having it rewrite; it's about asking pointed questions like 'What am I missing?' or 'What should I think about differently?' and then you, the human, do the revision. This dynamic mimics the way you'd discuss work with a knowledgeable peer, keeping you in the driver's seat. Dr. Wood notes this is similar to how we've always used external memory tools (encyclopedias, libraries) but with the dangerous convenience of having the tool think for us. By maintaining this protocol, you avoid the 'digital dementia' trap and continue building cognitive headroom.

Dr. Wood breaks down the dose relationship using UK Biobank data: the standard UK drink is 8g ethanol, half the US standard. When people average less than half a US drink per day, there's no net effect on brain volume or dementia risk. Above that, there's a dose-dependent reduction in brain volume and increase in dementia risk. He emphasizes the mechanism through REM sleep disruption, as REM is vital for creativity and integrating information. While he personally drinks occasionally (a few times a year), he does not consider regular low-dose intake safe, and certainly not binge drinking. He also pushes back cautiously against studies claiming no amount is safe, calling their statistical methods 'sketchy,' but stands by that regular consumption beyond truly minimal amounts is detrimental.

Dr. Wood explains headroom as the maximum capacity you have available. From a physical standpoint, it's the difference between the leg strength needed to get out of a chair (daily minimum) and your one-rep max squat (maximum capacity). When sleep deprivation, acute stress, or illness hit, you want that extra capacity to maintain function. The brain works the same way: you build headroom through a combination of stimulating, supplying, and supporting the brain — his 3S model. The goal is to maximize your cognitive reserve so that even when performance-diminishing factors appear, you stay sharp. This directly challenges the narrative that cognitive decline is an unavoidable part of aging; instead, it frames it as a mismatch between demands and built reserve, which can be actively managed.

Dr. Wood likens brain health to physical training: the most important thing is the stimulus you apply to your brain — skill learning, social connection, complex motor skills. Once you stimulate a brain network, neurovascular coupling increases blood flow to that area, demanding good cardiovascular function and metabolic health (glucose, ketones, lactate) as well as essential nutrients like vitamin D, omega-3s, and B vitamins. After stimulation and supply, you need support for adaptation, which occurs primarily during sleep and strategic rest periods. Additional support includes neurotrophic factors from exercise, hormones for neuroplasticity, and avoidance of chronic stress, inflammation, dental disease, and excessive alcohol. The key insight is that these three S's interact: improving sleep can improve blood pressure, blood sugar, inflammation, social behavior, and cognitive engagement, creating a virtuous cycle. Therefore, you don't need to fix everything at once; moving one lever shifts the whole network.

Dr. Wood argues that while some aging-related decline cannot be entirely prevented, much of what we expect is shaped by societal messaging. Osler's influence set a cultural narrative that equates aging with uselessness. As people absorb this expectation, they stop learning new skills, challenging themselves, moving enough, or prioritizing sleep because they anticipate decline. This withdrawal then causes actual cognitive loss. The Seattle Longitudinal Study supports this: following the same individuals over decades, more than half maintained cognitive function into their 70s and 80s, even though the average declined due to some who lost function dragging down the group. So, the average hides the reality that most people can stay sharp if they continue protective behaviors. The practical takeaway is to reject the narrative and keep engaging in cognitively demanding, physically active, socially connected lifestyles.

Dr. Wood explains that the brain needs periods of downtime for adaptation and connection formation, akin to sleep and recovery after physical training. In an environment where boredom was once inevitable, the brain would use that time for integrating and solidifying previously received cognitive stimuli. However, modern constant low-level stimulation—social media, notifications, always-available entertainment—means people never truly get bored and thus miss out on this crucial integration phase. This chronic partial attention drains cognitive resources and prevents the deep processing that builds resilience. He notes that being bored is not just empty time but a state where creativity increases and where adaptation occurs. The implication is that deliberately creating boredom—by disengaging from devices and letting the mind wander—is a strategic cognitive enhancement practice, not laziness.

Dr. Wood warns that the most common way people engage with AI—simply inputting a prompt and letting the model generate entire outputs—is likely detrimental to brain health. The MIT study showed that bypassing your own cognitive effort reduces activation in the brain networks involved in the task, produces work that is less original and more formulaic, and results in poorer retention. This is because the brain didn't do the work; skills and associated neural networks atrophy when not used. However, AI can be beneficial if approached correctly: first, perform the task yourself—write the essay, outline the presentation, do the research—engaging deep focus and attention. Then, use the AI in a conversational manner, asking it to identify gaps, suggest improvements, or provide alternative viewpoints. The crucial step is that you then personally integrate that feedback, doing the actual revision and incorporation yourself. This treats the AI as a cognitive orthotic that extends your current capacity rather than replacing it, preserving the brain-building benefits of focused effort while adding higher-order insights. Dr. Wood compares this to discussing your work with a knowledgeable colleague.