Accelerate Learning & Increase Cognitive Capacity | Dr. Tommy Wood
In a Nutshell
High-intensity interval training (Norwegian 4x4 protocol) outperforms moderate cardio for preserving hippocampal structure and function long-term, while resistance training uniquely supports white-matter integrity. Neuroplasticity is driven by novel, challenging activities—especially dance, ball sports, and learning instruments—combined with consistent nutrient status (omega-3s, B vitamins, vitamin D) and sleep. Optimal learning occurs in "clutch" states with friction and effort, not flow; sustainable deep work happens in 60-90 minute focused blocks, and acute post-exercise cognitive gains come from moderate arousal, not exhaustive sessions.
These notes were generated by AI and may contain inaccuracies.
A recent study randomized older adults into three groups: a low-intensity group, a zone 2 treadmill group training three times per week, and a high-intensity interval training group using the Norwegian 4x4 protocol. The 4x4 protocol consisted of 4 minutes at 85-95% of maximum heart rate with 3-minute rests, performed four times per session, three times per week for 6 months. The high-intensity interval training group improved fitness comparably to the zone 2 group but showed superior improvements in hippocampal function and maintenance of hippocampal structure on MRI. These benefits were maintained for 5 years after the 6-month intervention.
Dr. Tommy Wood is a medical doctor and neuroscience researcher at the University of Washington in Seattle. He serves as chief science officer of BetterBrain, a company providing free brain health coaching. His expertise covers neuroplasticity, human performance, and science-based protocols to improve focus, learning ability, and skill expression. His work applies to novices through elite experts across cognitive, language, athletic, and creative domains.
The discussion covers brain states that favor learning and how to access them, optimizing learning session duration and frequency, and improving the brain's capacity for learning itself. The conversation addresses flow states and clutch states, with clutch state identified as the optimal condition for learning and performance. Different exercise modalities including long slow cardio, brief high-intensity cardio, and various resistance training forms are examined for their distinct effects on neuroplasticity and learning.
Dr. Wood's recent book is titled The Stimulated Mind: Futureproof Your Brain from Dementia and Stay Sharp at Any Age.
Neuroplasticity is conceptualized as the brain responding to inputs to better navigate and survive the environment. Every learning, interaction, and memory engages neuroplasticity principles through forming new synapses, strengthening synapses, or weakening synapses. Brain development and functional refinement include pruning or removal of synapses, not only growth and new connections.
A common misconception conflates neurogenesis with neuroplasticity. The adult brain does not generate substantial new neurons, with possible limited neurogenesis in the olfactory bulbs and dentate gyrus of the hippocampus representing only a tiny number of cells. The misconception that limited neurogenesis means the adult brain cannot adapt or change is incorrect. Fixed cell numbers do not prevent changes in connections between cells, which occurs continuously and represents the main principle of neuroplasticity.
When learning motor skills such as billiards, improvement involves both strengthening new connections and removing or downregulating connections that decrease accuracy or prevent intended movements. After approximately age 2-3 years when neuron generation largely ceases, refinement of functions occurs primarily through removing connections based on exposures including language, motor, and social skills. This process continues throughout life.
Loss of function later in life may occur when inputs maintaining specific functions cease, allowing continued pruning. This aligns with the developmental theory of aging.
Maintaining cognitive function requires addressing three approaches: exercise, continuing existing activities, and attempting new activities. Epidemiological and intervention studies show that older adults engaging in cognitively demanding hobbies and activities including lectures, volunteering, reading, and crosswords exhibit slowed cognitive decline, better function maintenance, and lower dementia rates. These observations are primarily from continuing existing activities.
Reverse causation is possible, as individuals maintaining function are more likely to continue enjoyable activities.
Randomized control trials demonstrate that engaging older adults in novel cognitive activities produces functional improvements. Examples include language learning, complex coordinative movement or exercise, and musical training such as learning new instruments or musical theory. Improvements particularly in executive function appear most consistently across interventions.
Recent trials have employed online cognitive training platforms. The Maintain Your Brain study conducted in Australia targeted individuals primarily in their 50s and 60s with interventions across four domains based on individual risk factors: dietary intervention, physical activity, cognitive behavioral therapy for mental health concerns, and online brain training.
The POINTER trial conducted in the United States with adults in their 60s and 70s replicated the earlier FINGER trial from Finland. Interventions included diet, exercise, monitoring and treating cardiovascular risk factors, and brain training using the Brain HQ platform developed from the work of Mike Merzenich.
Brain training focused primarily on developing and maintaining processing speed. The ACTIVE trial conducted in the United States in the 1990s with adults in their 60s and 70s compared three training groups against controls: memory training using mnemonics and memory palaces, reasoning training identifying patterns in numbers and letters, and visual processing speed training.
A secondary analysis of the ACTIVE trial showed that participants receiving processing speed training with booster sessions at 1 and 3 years had significantly decreased dementia risk 20 years later. Processing speed training improves cholinergic signaling in the forebrain, which is susceptible to dementia processes.
Processing speed training presents information for very short periods, requiring participants to remember what was seen and its location. This differs from reaction time, which represents basic response to visual stimuli. Reaction time gradually decreases from approximately the 30s with potential acceleration after age 60. Processing speed remains relatively stable until approximately age 60 before declining.
Crosswords and sudoku provide meditative effects with focus but limited cognitive challenge. Building cognitive capacity requires activities that are both focused and cognitively challenging. Such challenges can come from learning new skills across motor, language, and social domains, ideally as broadly as possible.
The narrowness or breadth of the response is proportional to the narrowness or breadth of the stimulus. Getting really good at one very specific thing is possible, but learning a new skill that involves a wide variety of tasks creates broader potential for transfer into other areas of daily life. Learning a new ball sport requires multiple aspects of motor skills and social skills, and includes both visual and auditory processing that gets faster and harder the better you get. This creates a much broader stimulus than getting very good at one very specific brain training task on a single computer program. Online or digital brain training has the limitation that you get very good at doing that one specific thing but it does not transfer over to other areas of life. Broader, more complex, ultimately more human skills probably give much broader transfer because of the multiple pathways or networks that are being activated.
Ideally, pick something that is a bit outside or really outside your current skill set and that involves motor and cognitive aspects. Sport activities feel motor and cognitive because you have to learn the rules of the game and in some cases interact with others. Cognitive activities like writing or turning a page do not involve significant motor skills. Video games can improve reaction time and visual search, but basically your thumbs get really good. At a video game competition, the kids who compete warm up their hands and the audience uses styrofoam things so they clap without making noise.
Things like exercise and skills can be done separately. Aerobic and strength training do different things to different parts of the brain, so ideally do a little bit of both. Learning a new language has good evidence behind it. Dancing is probably number one for activities that hit multiple networks at the same time. Learning a new dance, whether solo or with someone else, is highly encouraged as a form of physical activity. The best evidence is for ballroom and line dancing, which generally requires other people as well as learning various sets of movements. Meta-analyses of these interventions in older adults show that ballroom and line dancing have the greatest effect on cognitive function. Both require other people, skill learning, social interaction, and a physical activity component. There is probably also a musical component because you have to listen for the timing of the music.
In the exercise realm, ball sports, board sports, and team sports are recommended. Skateboarding is a great example as long as you wear a helmet. Most martial arts work well as long as someone is not punching you in the face too much. Brazilian jiu-jitsu involves a physical component, a complex motor skill component, usually a social component, and a lot of responding and reacting to the environment or your opponent. There is interesting data on creative or visual arts that seem to have effects on network stability and function in the brain, particularly the frontoparietal network that is important for focus and attention and whose function tends to decrease with age. Learning a language and learning to play video games have similar effects because you have to solve complex problems and react quickly to a changing environment.
No one has looked at differences between specific instruments, so pick one that you feel motivated and interested to learn. Dancing by oneself has a lower shame quotient. The discomfort of making mistakes is critical for learning. Some of that discomfort can be important, but if you do it in a class where everybody else is a beginner and you are all doing it together, that adds a fun component because you can laugh at each other when you do not get it right.
A paper written with colleague Josh Tknet explored the idea that one of the reasons people lose cognitive function as they get older is because they stop giving their brain novel inputs or complex inputs that help maintain function and drive neuroplasticity. One of the reasons this happens is because adults hate being bad at things. The thought of going into a dance class and sucking at dancing creates anxiety. Imagining taking a tango class leads to fears of dropping your partner, making them mad, having lots of people see, and feeling stupid. This is why people do not do those things. Making mistakes is critical to driving the processes of neuroplasticity, so it is necessary to let go of some of the expectations adults feel that everybody expects them to be good at everything and the best at everything without failing or making mistakes. Acknowledging that the shame component exists and leaning into it is going to be a really important part of trying to maintain this function over time.
Grandparents on the Argentine side did tango until they were into their 80s, though they learned it rather young. Tim Ferriss learned tango and got a dance coach, a female dance coach, to teach him how to lead, then learned how to lead and was able to dance tango competitively. Traditionally the male leads in dances like salsa and tango. Following is not trivial and requires some skill, but if the person traditionally the male cannot lead, the whole thing does not work. A roommate who was a neurology resident at UCSF would go do tango late at night and come back a different person.
When trying something truly new that involves interactions with other people and entering into beginner's mind while embracing the shame, as you start to get even just a little bit better at something, there seems to be a kind of halo around the rest of life. You go to work the next day differently and interact with people differently because your nervous system has changed. This general change in arousal leads to sleeping better and being more excited for the other things in life.
A core need exists to be challenged and then to overcome those challenges. There are downstream effects of not doing that, which could be related to mental health or physical health. The process of overcoming challenges drives a lot of physical or mental psychological growth. Fundamentally this is part of what is needed on a daily basis. Doing something you were bad at and getting better at it proves to yourself that you are capable and able to overcome challenges and engage in difficult things. The psychological benefits of engaging with a challenge, overcoming it, and working hard to do that are almost like a core psychological need. That transfers to other things, creating the sense that you can do hard things, do other things, and be excited to try something else that is difficult and challenge yourself again. It needs to be something that feels meaningful and difficult enough that you have the ability to overcome it with some dedicated practice or focus time working on it. If it is too hard, you can have the opposite effect by making something so difficult somebody cannot do it and they just fail again and again. Something you can get better at, work on, and see progress has all these knock-on effects.
Mihaly Csikszentmihalyi defined flow as being engaged in a process where you have a certain level of skill but the thing you are trying to do is just beyond your skill level, really striving a bit, and that general sense of well-being that can come from that. Nowadays people assume flow is when you are able to do something in the absence of a feeling of effort, which is not what flow was originally intended to mean. Flow is a meaningful concept but it is not really known how to define it. What is seen in movies and media is that suddenly people are endowed with powers just because they want them and need them, and that is not how it works. Flow is the maximal expression of a complex learned skill where you are right at the edge of your capabilities but you are still managing to maintain function whatever skill you are performing. People assume that for optimal performance you need to be in flow, but that is not true. Flow is one version of being able to perform at the best of your abilities.
In sports performance there are broadly two states associated with top level performance: flow states and clutch states. In a clutch state you are still at the optimal level of arousal required for you to perform the skill you are trying to perform, but it still feels like hard work. You could talk to any athlete about a time that they performed well, won, and did at the best of their abilities but it was hard cognitive work and hard physical work. It was a slog, but they still managed to perform well. People can perform at the best of their abilities in clutch states even though they are not in flow and it is not all coming to them easily. It requires them to really focus and work hard to get the job done. Both of those are perfectly reasonable states in which to perform. Assuming that you have to be in flow to perform just is not true if you look at how athletes perform in the moment.
Flow is not required for learning, and optimal learning does not happen in flow. Making mistakes and errors and friction are required for learning, which is not conducive to flow because it can be stressful and frustrating. If flow is expressing your skill and you want to get better at that skill, you have to work even further beyond your current capacities, which will move you out of flow because of the friction, the mistakes, and the errors that come from that. There are all these other states where learning happens and where performance happens that are not flow, and that is fine too. Sometimes it is hard and that is okay.
The anterior midcingulate cortex is the structure that maintains size in super-agers who take on hard things and is associated with tenacity. When stimulated in neurosurgery experiments done by Joe Parvizi at Stanford, people feel like there is an impending challenge and they are going to lean into it. This sounds more like the clutch state than the flow state. The thing to embrace is the clutch state. A good friend from the special operations community talked about performance years ago and described unskilled, skilled, mastery, and virtuosity. Virtuosity is when someone who has mastery pushes out to an edge of effort where they are sort of inviting in the unknown. They do not quite know what they are going to do next. They have some semblance of an idea and they are not being haphazard, but there is an inviting in of the unknown and they find themselves at a new level.
The documentary The Dark Wizard is about Dean Potter, who was a free climber, a free solo climber, turned wingsuit flyer. In that documentary you see how somebody who is pushing to their edge and a little bit beyond, where the consequence is death, is able to access levels of skill that are jaw-dropping even to him. Virtuosity requires a specific scenario and moment of performance. People might talk about virtuosos in a skill just because they are so much better than everybody else, but that definition requires a specific scenario and moment of performance. There is a famous quote from Ayrton Senna where he is driving in the Monaco Grand Prix and describes going faster and faster. He feels like this is beyond his capabilities and he does not feel like he is actually connected to doing the thing. It is just kind of happening. He is going seconds faster around the lap than anybody else. That is displaying virtuosity under that definition, and there is a lot of overlap with flow.
Twyla Tharp, who is in her 80s and a world-class choreographer, described the daily routine of her world-class dancers. They go through the most basic drills every single day, but every iteration for hours upon hours upon hours before they begin practice, before they try and embrace the new performance piece. Often this is after multiple hours of morning exercise. The foundational work is not seen and it needs to be maintained. In athletes and sports, particularly on the training side, there is the general idea of thirds. A third of your sessions, training, learning, whatever it is, are going to feel great. You are going to feel really good. You are just going to get stuff immediately. It is going to just come to you.
Performance naturally varies day to day and week to week. A third of the time performance feels great, a third is average, and a third feels difficult. This undulation occurs across days, weeks, months, and years. The glorification of flow states creates an expectation that skills should always come easily, but this contradicts the requirement to work hard and challenge oneself to build capacity and drive neuroplasticity.
Whether to maintain fundamentals depends on the specific skill. A study on pianists examined older and younger participants in their 20s-30s and 50s-60s, comparing expert pianists from German music conservatories to amateurs. Researchers assessed basic task-specific skills such as finger movement. The most important predictor of performance on piano-specific skills was not age but how much participants practiced. Getting repetitions in helps maintain basic functions.
When performing complex piano pieces, fundamentals are often encompassed within the practice. Some pianists still do scales as part of warming up to get into the mode of playing complex pieces, and this may also help maintain fundamental skills.
The 10,000 hours figure from the Ericsson violinist studies represented the average amount of practice time expert violinists had accumulated by age 20. This number does not represent a fixed requirement for expertise, and the violinists were not yet experts at that point. Expert violinists tended to practice in two sessions of 60 to 90 minutes per day.
For hard cognitive work involving focus and challenge, people can sustain this for chunks of 20 to 30 minutes with breaks. The Pomodoro technique of 25 minutes with a 5-minute break fits this rhythm. Hard cognitive work and learning happen sustainably in these chunk sizes.
One experienced writer was told that four solid hours per day, broken into a couple of sessions, represents the realistic limit for focused writing. When examining past six-hour work sessions, actual focused time was lower due to breaks, meals, and other activities. Pushing to 6, 8, 10, or 12 hours of non-stop work during deadline periods led to compensatory drops in output afterward.
Focused clutch state work occurs somewhere between 60 to 90 minutes per session and perhaps four hours total, but not much more than that.
Eliminating distractions is one of the most important factors for deep focused work. This includes closing email, putting the phone in a different room, and closing Slack or Teams. Gloria Mark's book Attention Span addresses this topic. People get used to patterns of distraction such that even when not being distracted externally, they distract themselves by reaching for their phone.
Eliminating notifications helps, but high friction in a task can cause stepping away. At a sticking point, switching to another project and returning later represents a normal work pattern. Deadlines create natural focus where distraction becomes less of an issue, though this typically lasts only a day or two rather than extended periods.
Research shows that having a phone on the table or even in a bag beneath the chair, even if turned off, creates a cognitive cost. Cognitive flexibility suffers because the brain unconsciously expects a call. Meditation provides forced periods without breaks or distractions. Even if the mind drifts during meditation, this can allow integration time and new connections, similar to how ideas emerge in the shower when phones and other distractions are absent.
Most cognitive and psychological interventions use versions of the Mediterranean diet. The MIND diet, developed from the Rush University Memory and Aging Project, combines the Mediterranean diet with the DASH diet for blood pressure management. It emphasizes seafood, vegetables, berries, and whole grains while limiting saturated fat and animal protein.
The SMILES trial was the first randomized controlled trial showing that a Mediterranean-style diet produced significant improvements in mood symptoms for depression. A large New England Journal of Medicine trial comparing the MIND diet to standard caloric restriction found similar benefits in both groups.
Observational studies show that diets resembling the Mediterranean pattern correlate with lower dementia risk. A UK Biobank analysis tested whether removing individual components like olive oil or meat changed the relationship between Mediterranean diet adherence and dementia risk. No single food or food group altered the relationship, indicating that overall diet quality and nutrient density matter more than any specific component.
Energy availability follows a bell-shaped curve with brain volume. Chronically calorically restricted individuals show smaller brain volume due to insufficient resources for structure and maintenance. Chronically calorically excessive individuals also show smaller average brain volume, related to metabolic disease, inflammation, and high blood pressure. The caloric restriction group in the MIND diet trial may have benefited from moving energy intake toward an optimal range that supports physical and cognitive health.
Critical nutrients with the best evidence for cognitive function and dementia risk include:
- Vitamin D
- Iron
- Omega-3 fatty acids
- B vitamins involved in methylation, particularly B12 and folate, with potential roles for B6 and riboflavin
Additional nutrients with good evidence include antioxidant polyphenols from berries, coffee, tea, and chocolate; carotenoids that produce orange, yellow, and red colors; lutein, zeaxanthin, and astaxanthin from seafood; and dietary fiber. Magnesium and zinc are also important. Structural lipid components like choline and ethanolamine from nuts, seeds, and eggs show relationships to cognitive function.
Nutrient interactions and timing are rarely studied. Whole foods provide multiple beneficial compounds plus fiber, but consistency can be difficult during travel. Supplements offer daily consistency to maintain nutrient ranges.
Adipose tissue stores excess omega-3 fatty acids. Long-chain omega-3s stored in fat tissue may explain why supplementation results vary across trials. When lipolysis occurs during exercise or sleep, stored omega-3s are released and become available to the brain.
Phospholipid-form omega-3s, found in krill, show greater brain uptake after a single dose compared to triglyceride-form omega-3s found in fish oil. However, over several days of supplementation, both forms produce similar results because the triglyceride form cycles through adipose tissue stores and is released for brain use. Eating seafood early in the week provides adequate omega-3s without needing supplementation later in the week, especially for individuals with consistent lifelong seafood consumption who have built adipose stores.
A recent trial examining omega-3 supplementation for dementia risk reduction and cognitive improvement
A recent trial from USC examined omega-3 supplementation for dementia risk reduction and cognitive improvement. Participants received omega-3s for a long period and researchers measured omega-3 levels in cerebrospinal fluid to confirm the fatty acids reached the brain. The trial showed no changes in cognitive function or brain structure on MRI scans, leading many to conclude omega-3s do not work. However, participants did not appear to be omega-3 deficient at baseline, meaning additional supplementation provided little benefit.
The best approach when accessible is to test nutrient levels rather than supplement blindly. Recommended tests include vitamin D levels, hemoglobin and iron levels, omega-3 levels, and homocysteine levels as a marker of B vitamin status. Homocysteine is a known risk factor for cognitive decline and dementia.
Normal lab ranges do not always align with optimal risk ranges. For homocysteine, the normal range may extend to 15 or 16, but risk is elevated above 13 and likely above 10 to 11. Supplementing to bring elevated homocysteine down produces significant improvements in cognitive function or slowed decline. This applies particularly to omega-3s and B vitamins that lower homocysteine.
Multiple randomized controlled trials demonstrate that omega-3 status and B vitamin status interact and depend on one another. The VITACOG trial from the University of Oxford first showed this interaction, later replicated in the B-PROOF trial. When B vitamins are given to individuals with elevated homocysteine but poor omega-3 levels, no cognitive benefit occurs. The reverse was also demonstrated in the OMEGA-AD trial: omega-3 supplementation provided no benefit when participants had elevated homocysteine.
The COSMOS study provided thousands of older adults with either a multivitamin (Centrum Silver) or a cocoa flavonol supplement. The multivitamin group showed cognitive function changes suggesting improvement. The supplement contained only 100% of the recommended daily allowance without high doses. The flavonol supplement benefited only those with poor diet quality at baseline; individuals already consuming coffee, berries, fruits, and vegetables derived no additional benefit.
Blood testing enables tailored supplementation decisions made collaboratively between patient and provider. Retesting confirms whether levels move into desired ranges. Subjective measures of well-being and sleep should accompany objective blood data. Current technology makes this approach feasible, though many still view supplements as wasteful.
Supplements fall into distinct categories: basic vitamin and mineral repletion, food replacement, and targeted compounds for specific effects such as faster sleep onset, increased slow-wave sleep, or enhanced focus.
One gram of EPA daily may be beneficial, but whether three grams provides superior results even when already at upper reference ranges remains unaddressed. The past 40 years of nutrition research focused primarily on what to avoid: trans fats, fried foods, excess energy intake, and excessive alcohol. Attention is now shifting toward what actively improves health and performance.
At the population level, improving brain health requires raising the floor through better food quality and equitable access. Nutrients act as a great leveler regardless of dietary pattern; the priority is obtaining required nutrients whether from food or supplements. Once basic needs are met, the question becomes how much further function can be pushed. Current evidence indicates avoiding deficiency is sufficient, though whether higher levels confer additional benefit is unknown. Individual experimentation with controlled variables and meaningful outcome tracking may clarify these questions.
In the 1990s and 2000s, individuals used compounds to enhance performance without public disclosure. Two changes occurred: market incentives encouraged sharing protocols, and GLP-1 receptor agonists reduced needle phobia. Women now represent major consumers of peptides, driven partly by cosmetic motivations. This shift has normalized injectable compounds beyond traditional gym contexts.
Many adults with families are inquiring about microdosing retatrutide and tirzepatide for weight loss, BPC-157 for injury repair, and GHK copper for skin appearance. Most peptides lack high-quality human evidence of efficacy except GLP-1 agonists. Growth hormone secretagogues carry insulin resistance and diabetes risk at higher doses.
Before trying any new supplement or peptide, documented evidence of safety in humans should be established. Even without proven efficacy, known safety allows low-risk experimentation. Most peptides lack both long-term safety data and efficacy data for intended uses. Creatine stands out as an exception: it is very safe even at high doses in frail older adults, though individual response varies for cognitive and physical performance benefits.
How an athlete feels is a stronger predictor of performance than HRV or blood markers. Simple rating scales asking how good someone feels on a 1-10 scale outperform most physiological data. The REST-Q questionnaire assesses perceived recovery and motivation to train. Mindset can override objective sleep scores when individuals honestly assess their current state.
Stimulants such as caffeine can dissociate subjective feeling from objective performance. Studies using the n-back task show caffeine makes participants feel they are performing better while actually impairing performance on complex working memory tasks.
People taking caffeine during complex cognitive tasks often feel like they are performing better, yet objective measures show they make more errors and react too quickly without adequate thinking. Similar patterns appear with other stimulants. A paper published in Science a couple of years ago examined methylphenidate and other ADHD medications given to people without ADHD. These individuals reported feeling great, yet performance data revealed the same dissociation between subjective experience and objective results.
Cannabis produces the inverse effect: users believe they have generated great ideas, but the next day they recognize the output as poor. Studies have formalized this by having others objectively rate creativity. Cannabis users felt more creative but were not rated as more creative by external evaluators.
This dissociation matters when evaluating supplements. Feeling better does not necessarily mean performance has improved. Endogenous increases in arousal, such as those produced by exercise, avoid this mismatch and provide more reliable cognitive benefits.
Exercise reliably increases arousal and improves cognitive function across multiple domains, including learning and retrieval. This effect occurs with resistance training, aerobic exercise, and very brief sprints, provided the exercise is not truly exhaustive. Maximal efforts such as a 2K rowing test or intense CrossFit sessions leave the brain impaired afterward.
When cognitive work must follow training, leaving some volume in reserve is beneficial. Low-volume, high-intensity approaches (for example, two sets per exercise across two or three exercises per muscle group) tend to produce a net cognitive boost rather than fatigue. Exhaustive sessions can be used when the goal is maximal adaptation, but they impair immediate subsequent cognitive performance.
Student athletes at D1 schools illustrate this tradeoff clearly. When training loads are very high, they must sit in the front of class and take deliberate steps to maintain attention, as fatigue makes focus difficult, especially with phones and tablets present.
Optimal training volume depends on current capacity and upcoming cognitive demands. When hard cognitive work (exams, writing, data analysis, reading papers) is scheduled afterward, workouts should remain below typical maximal efforts. Meta-analyses indicate that 20- to 30-minute jogs provide the strongest immediate post-exercise cognitive benefits.
Even modest arousal increases appear sufficient. Catecholamines (adrenaline, norepinephrine, dopamine) and cortisol contribute to alertness. Short, high-effort sprints with long rest intervals or brief resistance sessions produce comparable effects without requiring large catecholamine dumps. The goal is to move arousal into an optimal range for focus rather than to induce maximal physiological stress.
Different exercise intensities produce different long-term structural outcomes. A well-known study had older adults perform 40 minutes of brisk walking (zone 2) three times per week for one year. Participants showed increased hippocampal volume, improved VO2 max, elevated circulating BDNF, and better memory.
A more recent randomized trial compared three groups of older adults: low-intensity, zone 2 treadmill work, and high-intensity interval training using the Norwegian 4x4 protocol (4 minutes at 85-95% max heart rate with 3-minute recoveries, performed four times). All groups trained three times per week. The high-intensity group achieved similar fitness gains but demonstrated superior hippocampal function and better maintenance of hippocampal structure on MRI. These benefits persisted for five years after the six-month intervention. Within the study, greater work intensity and higher cortisol release correlated with larger hippocampal improvements.
High-intensity work releases myokines and lactate. Lactate readily enters the brain and stimulates BDNF production, supporting neuroplasticity. The data contradict claims that high-intensity exercise is inherently harmful due to cortisol release; the cortisol response appears integral to the structural and functional gains observed.
One high-intensity session per week is generally sustainable alongside three weekly resistance sessions and one longer, slower cardio session (45-60 minutes). Adding a moderate-intensity zone 3-4 session provides further variety without excessive stress.
Morning cortisol elevation is normal and beneficial for daytime energy and nighttime sleep. Moderate resistance or cardio sessions can triple or quadruple baseline cortisol transiently; this response is not pathological. Chronic, unrelenting stress is the concern, not acute elevations from training.
Hans Selye's general adaptation syndrome described how chronic stress can lead to exhaustion of physiological systems. Acute stress, however, drives adaptation. The stress response diverts resources (for example, glucose to the immune system during infection) so the organism can respond to and ultimately handle the stressor more effectively.
Exercise-induced cortisol and catecholamine responses mirror those seen in illness or injury. These molecules support adaptation, including neuroplasticity. Regular exercise also confers cross-stressor resilience: individuals who train regularly show smaller dips in mood and cognitive function when exposed to psychological stress.
Hypostress (insufficient stress) prevents adaptation and fails to build function. Intermittent exposure to manageable stressors is therefore essential. When sleep begins to erode, training or life stress likely needs adjustment.
For acute arousal and cognitive enhancement, typical sessions of a couple of sets of 8-12 repetitions at roughly 80% of max, using compound movements on machines (leg press, chest press, lat pulldown, shoulder press), lasting 20-30 minutes, produce benefits comparable to a 20- to 30-minute jog. Slightly higher intensity can be used if recovery remains adequate.
Long-term studies in older adults typically employ two or three sessions per week, five to six multi-joint machine exercises, three sets of 8-12 repetitions. After 6-12 months, participants show improved white-matter structure and better executive function.
White matter constitutes approximately 60% of the human brain and consists of myelinated axons that enable rapid information transfer. Aerobic exercise (zone 2 to zone 4-5) preferentially benefits gray matter, including the hippocampus. Resistance training preferentially benefits white matter. Loss of white-matter integrity is one of the strongest predictors of age-related cognitive decline, independent of amyloid and other neuropathology.
IGF-1, which rises particularly with resistance training, supports white-matter development and maintenance throughout life. Thus aerobic and resistance training produce complementary structural effects: aerobic exercise supports gray-matter and memory functions, while resistance training supports white-matter and executive/processing-speed functions.
Both modalities should be included for comprehensive brain health.
Most compounds studied reduce REM sleep rather than increase it. The primary way to increase REM is through sleep deprivation followed by REM rebound. A review by Jeff Lickman and Josh Sains examined long-term potentiation and found that applying almost any molecule to neurons during the LTP protocol produced an enhancement. This highlighted a broader theme: certain processes like REM sleep are easily disrupted by minor tweaks to the system, while long-term potentiation can also be readily tilted up or down in isolated neurons or animals.
The human body deploys numerous molecules simultaneously. This explains why plasticity, which underpins learning and memory, is driven by both resistance training and cardiovascular training since both are motor activities. Crossword puzzles produce some plasticity effects, but activities like dance that incorporate social inputs, balance demands, and multiple variables likely produce stronger effects. Earlier views treated exercise-induced plasticity as limited to increased neuron production in mice, which did not translate meaningfully to human memory or protection against cognitive decline. Newer understanding positions resistance training and cardio protocols such as 4x4 intervals as genuine plasticity triggers that deploy multiple interacting molecules.
Dementia represents the end stage of cognitive decline where individuals can no longer perform basic activities of daily living. Alzheimer's disease accounts for 60-80% of dementia cases. Vascular dementia is the next most common form, and the two frequently overlap with most Alzheimer's patients showing vascular changes in the brain. Other types include dementia with Lewy bodies, frontotemporal dementia, and dementia related to Parkinson's disease. It is now accepted that potentially half of dementia cases are preventable, with the majority falling into Alzheimer's and vascular categories. Metabolic disease and other Alzheimer's risk factors also elevate risk for Parkinson's and additional dementias.
A small fraction of Alzheimer's cases, less than 5% and possibly as low as 1%, result from monogenic dominant mutations in the presenilin 1 and 2 genes or the amyloid precursor protein gene. The vast majority is late-onset Alzheimer's, which occurs earlier in some populations. Genetic risk includes the APOE gene and polygenic risk involving thousands of genes, but lifestyle and environment exert stronger influence than in early-onset monogenic forms.
The Lancet Commission on Dementia Prevention, overseen by Professor Jill Livingston, identified 14 modifiable risk factors accounting for approximately 45% of dementia cases. These include early-life education, high blood pressure, diabetes, hearing loss, vision loss, brain trauma, high LDL cholesterol, and low physical activity. Hearing and vision loss matter because degraded sensory inputs reduce stimulation. Social isolation was also listed. Sleep deprivation was discussed but excluded due to insufficient evidence level, though the threshold for increased risk appears around consistently sleeping fewer than 6 hours. The final two REM-enriched cycles are particularly important for cognitive health.
Nutrient status including omega-3 fatty acids and B vitamins was also omitted despite supporting interventional and observational data. Other analyses suggest these factors could contribute meaningfully to population attributable risk, implying the 45% figure may be conservative. Some studies estimate up to 70% of dementias could be preventable when including socioeconomic and societal factors, though these are harder to modify at the individual level.
Several large natural experiments in the UK (Wales), Australia, and Canada examined the effect of the shingles vaccine on dementia. In each country, eligibility for the vaccine shifted on a single date, creating a natural experiment where people born one day apart were otherwise similar. Those eligible for or receiving the vaccine showed consistently lower dementia risk. The studies used the older live attenuated Zostavax vaccine. A US study comparing the switch to the newer recombinant Shingrix found both vaccines lowered risk compared to no vaccine, with Shingrix showing a stronger effect.
A common observation is that Kaplan-Meier curves diverge early, within months, which is faster than the natural progression of dementia would predict. This raises the possibility of residual confounding where vaccinated populations differ in unmeasured ways. Nevertheless, the signal is considered credible enough to warrant an adequately powered randomized controlled trial currently in planning. Proposed mechanisms include reduction in painful shingles episodes that limit activity and social engagement, plus potential immunomodulatory effects. Most studies show a slightly stronger signal in women than men. Herpes viruses, including the shingles virus and herpes simplex virus, reside on neurons without killing them, providing a mechanistic link to dementia risk.
The studies involved people in their 70s and 80s. Guidelines in the US recommend vaccination in the mid-50s to prevent shingles, but dementia risk reduction data come from older populations.
Cognitive function does not decline linearly with age. The largest drops occur stepwise after significant illness. The Adult Changes in Thought study at the University of Washington and the Rush Memory and Aging Project both documented this pattern. Individuals experiencing major illness between cognitive assessments showed step declines, with even larger drops following hospitalization. Avoiding severe illness preserves function by maintaining activity, social inputs, nutrition, and sleep. This provides one rationale for why certain vaccinations may support long-term cognitive health.
After medical evaluation rules out bleeds or other acute complications, several low-risk, potentially high-benefit interventions exist. Temperature regulation is critical: prevent hyperthermia rather than relying on hypothermia. Concussions often occur in hot environments; moving to a cool setting quickly helps. If fever develops, acetaminophen can assist thermoregulation. Hyperthermia widens the gap between energy demand and mitochondrial energy production, promoting cell death and neuroinflammation.
Blood sugar regulation matters because elevated glucose after brain injury correlates with worse outcomes. Avoiding super sugary refined carbohydrates is advisable. Alcohol should be avoided because it impairs sleep, which is essential for recovery. Caffeine is similarly cautioned against as a stimulant that increases energy demand during a period of mitochondrial dysfunction.
Creatine shows reasonable evidence. One key pediatric trial spanning ages 1 to 18 used 0.4 grams per kilogram per day. For a 70-kilogram person this equates to 28 grams daily, roughly double a standard loading dose.
Recent meta-analyses show that GI side effects with creatine are actually quite rare compared to placebo. Some GI issues may stem from poor quality supplements containing adulterants. High doses can saturate creatine transporters, preventing absorption and drawing water into the gut, potentially causing diarrhea. For non-head-injured individuals, traditional loading protocols of 20 grams per day in grape juice are not necessary for long-term supplementation. In clinical settings, 20 to 30 grams spread across the day represents the evidence-based loading protocol. Studies using traditional creatine monohydrate and measuring brain creatine levels employed loading protocols for one week to achieve significant increases in brain creatine. However, benefits for mood, memory, and cognitive function in older adults can occur at standard doses of 5 to 10 grams without loading.
Magnesium dosing is 400 milligrams once or twice daily. Clinical trials used magnesium oxide, though magnesium glycinate is recommended for higher bioavailability. Athletes typically require additional glycine, making glycinate a suitable choice. Any bioavailable form is acceptable.
Several studies in collegiate American football players demonstrate that taking a couple of grams of omega-3s daily across a season reduces accumulation of injury biomarkers such as neurofilament light in the blood. For individuals at risk of concussion due to sport or occupation, long-term omega-3 supplementation is recommended based on reasonable supporting evidence.
Melatonin has shown improvements in sleep studies. High doses of branched-chain amino acids also improve sleep in TBI patients, with studies using up to 60 grams total. One veteran study administered three doses of 20 grams of BCAAs spread across the day. This effect is specific to TBI, as high-dose BCAAs outside of brain injury may impair sleep by competing for tryptophan uptake and reducing serotonin and melatonin production.
Iboga studies examining TBI and brain recovery are noted, with ibogaine being the most powerful long-lasting psychedelic. Data in people with brain trauma and PTSD history show promise. Other psychedelics may offer benefits through neuroplastic effects, particularly at macro or psychedelic doses. Existing trials are compelling but conducted in controlled clinical settings with heart rate monitoring. Ibogaine remains illegal in the United States, though regulatory shifts are occurring.
Choline, particularly in the form of CDP-choline or citicoline, has best evidence at 1 to 2 grams per day. Additional supplements with evidence include Boswellia (Indian frankincense extract), tested in three clinical trials showing benefit after TBI, and Enzogenol (pine extract) with slightly less evidence. The primary nutritional supplements are recommended as the foundation, with additional compounds considered for specific symptoms.
Return to physical activity as soon as possible after concussion is critical, provided no additional head injury occurs. Guidelines have shifted from rest in a dark room to early low-level aerobic activity. Standard care involves physical therapy if cognitive or physical symptoms persist beyond one month. Protocols include low-level aerobic activity two or three times weekly at a level just below symptom exacerbation threshold. Progression moves from non-specific aerobic exercise to skill-specific and sport-specific exercises, then full training and return to play. Virtual reality or augmented reality physical activity may improve cognitive symptoms. Vestibular therapy addresses balance and dizziness. Ocular motor training targets convergence and eye movement issues common after concussion. Eye tracking establishes baselines and tracks deficits over time, particularly in professional sports settings.
Dr. Tommy Wood, age 41 and 6'2", weighing 210-215 pounds, competes in the lightweight masters category for athletes over 40. Weight classes apply, with competitors under 200 pounds classified as lightweight. Water cuts are used to meet the 200-pound threshold for weigh-ins occurring 20-24 hours before competition, with weight regained by the following day. The Natural World's Strongest Man competition features seven events. A standard local or regional competition includes five events.
Events typically include deadlifts, overhead pressing, medleys involving carrying objects, lifting stones, farmers walks, and truck pulls. The upcoming competition includes a farmer's walk with 120 kilos (264 pounds) per hand for maximum distance within a 60- or 90-second time cap, with the ability to set the implements down. A yoke walk with 700 pounds is performed for maximum distance in the time cap. Completing 30 meters (approximately 90 feet) leads to circus dumbbell reps at 110 pounds then 135 pounds, performed from shoulder to overhead. A loading medley involves sandbags and kegs weighing 200-300 pounds loaded over a platform. A maximum squat uses an axle bar with pads at a specific height, with weight options of 170 kilos (approximately 375 pounds) and 200 kilos (approximately 440 pounds). Log press for reps uses 100 kilos (220 pounds) then 120 kilos (264 pounds). A sled push is followed by loading a 275-pound sandbag for dragging within a time cap.
The Natural World's Strongest Man competition occurs at the end of August and will not be streamed online, though content may appear on Instagram. Oral health is noted as important for cognitive function but was not discussed in detail. The conversation concludes with thanks for the discussion on neuroplasticity, brain injury recovery, and athletic pursuits in adulthood.
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