The Stimulated Mind: How Everyday Habits Shape Brain Health | Dr. Tommy Wood

Full analysis

Dr. Tommy Wood, a neuroscientist and associate professor at the University of Washington, argues that the majority of dementia cases may be preventable through consistent lifestyle habits — exercise, sleep, nutrition, social connection, and cognitive challenge. The conversation covers what actually builds cognitive reserve, which supplements have real evidence behind them, and what people already living with memory decline can do right now.

What was covered

• How much dementia is preventable. Wood cited the Lancet Commission on Dementia Prevention (led by Professor Jill Livingstone), which estimates 45% of dementia cases may be preventable. He added that when sleep, nutrient status, and socioeconomic factors are included — variables the Lancet report omitted — some analyses push that figure toward 70%.
• Neuroplasticity basics. The adult brain makes almost no new neurons after early childhood; most neuron production ends between ages one and three. Two exceptions: the olfactory bulb and a part of the hippocampus called the dentate gyrus. Brain health in adulthood depends not on making new neurons but on building and refining connections among existing ones.
• What "superagers" actually do. Wood described research showing people who maintain cognitive function from their 50s into their 80s — which he said studies going back decades suggest should be the norm — are consistent about physical activity, sleep, metabolic health (avoiding diabetes and heart disease), social connection, and cognitive engagement. They do not do anything exotic.
• Activities that build cognitive reserve. Wood singled out dancing, learning a language, playing music, and complex coordinative sports (tennis, badminton, yoga, team sports) as having the strongest evidence — randomized controlled trial evidence — for improving cognitive function and lowering dementia risk. Simple "brain games" and finger exercises, he said, he has "very little faith" will be sufficient.
• Preterm birth and dementia risk. Roughly 10% of U.S. babies are born preterm. Scandinavian population studies (which track individuals from birth to death) show the earlier the birth, the higher the risk of dementia, stroke, heart disease, and earlier mortality. Wood said this is likely driven by inflammation during pregnancy, early developmental disruption, and higher rates of metabolic disease in adulthood.
• Concussion and brain recovery. Traumatic brain injury — including concussion — is on the Lancet Commission's list of modifiable dementia risk factors. The current clinical recommendation has reversed: rather than rest in a dark room, patients should resume graded aerobic exercise (cycling, walking, jogging) as soon as able. Wood also noted B vitamins, vitamin D, and omega-3s as relevant to recovery.
• Supplements with the best evidence. Wood ranked omega-3 fatty acids (EPA and DHA), vitamin D, B vitamins (B12, folate, B6, and B2/riboflavin — specifically those that lower homocysteine, an established dementia risk marker), iron (especially in women), and creatine monohydrate as having the most credible evidence. Choline (sold as cognizin or citicoline) has some evidence but mainly in people already experiencing mild cognitive impairment, and can be obtained from eggs.
• Exercise prescription. Aerobic exercise (brisk walking and above) benefits gray matter and the hippocampus, supporting memory. Resistance training benefits white matter and supports executive function and decision-making. Wood recommended two to three aerobic sessions per week, one with some high-intensity intervals, plus one to two strength sessions — or substituting a dance class or ball sport for some aerobic sessions to add coordination and social benefit simultaneously.

Notable claims & predictions

• Wood on dementia prevention: "When you look at other analyses, including factors that weren't included in the Lancet report… some estimate that we might be able to prevent upwards of 70% of cases of dementia."
• Wood on superagers: "We have evidence that [maintaining cognitive function from your 50s into your 80s] should be the norm. There are studies going back several decades that show that most people can actually maintain their cognitive function from midlife into their 80s and beyond. We just didn't really realize it."
• Wood on iron: "About 10% of women are iron deficient. Iron deficiency increases the risk of dementia." He added that cognitive changes during perimenopause and the menopausal transition appear higher in women with low iron.
• Wood on concussion treatment: "Previously if you had a concussion, the recommendation was go lie in a dark room and do nothing. Now we know that actually as soon as you can, you need your brain to be active again" — with graded aerobic exercise recommended as soon as the person is able.
• Wood on creatine: "It's the most studied supplement, I think, of all of them, and we know it's incredibly safe." He noted a long-term study giving 10 grams per day to postmenopausal women in combination with resistance training showed potential additional benefit for bone health, and that some studies suggest benefit for cognitive function and mood in older adults.
• Wood on self-testing as a memory tool: Citing researcher Charan Ranganath's book Why We Remember, he said that actively quizzing yourself on what you just read or watched — even if you get it wrong — creates a memory structure that improves recall next time. He called this important for everyone, not just those with a diagnosis.

Fact check

Wood's claim that the Lancet Commission estimated 45% of dementia cases are preventable — Accurately stated. The 2024 Lancet Commission on Dementia Prevention, Intervention and Care (updated from earlier editions) does identify a set of modifiable risk factors with a combined attributable fraction in that range. The "upwards of 70%" figure is described as coming from analyses that add sleep and socioeconomic factors; this is a plausible characterization of some published modeling work, but Wood appropriately hedged it as an estimate rather than a settled finding. Neither number should be treated as a precise forecast.

Wood's claim that neuron production ends largely between ages one and three — Consistent with the mainstream scientific understanding, though the field has ongoing debate about the extent of adult hippocampal neurogenesis. Wood did acknowledge that some neurons are produced in the hippocampal dentate gyrus and the olfactory bulb in adults, which is accurate.

The claim that rest in a dark room was once the standard concussion protocol — Accurate. Clinical guidelines have shifted over the past decade toward early graded activity; current guidance from sports medicine and neurology organizations does recommend returning to light aerobic exercise as soon as symptoms allow, rather than prolonged cognitive and physical rest.

Wood's 10% iron-deficiency figure for women in midlife — Plausible as a rough estimate for iron deficiency broadly, though rates vary by population, age group, and definition used (ferritin vs. hemoglobin vs. anemia). Anemia rates in midlife women are typically lower than 10%; iron deficiency without anemia is more common. The link between iron deficiency anemia and cognitive outcomes is supported by research, but Wood presents the association with somewhat more certainty than the evidence base fully supports for cognitively healthy midlife women specifically. Worth discussing with a doctor and having iron and ferritin tested rather than supplementing without testing, since excess iron carries its own risks.

Creatine study in postmenopausal women: Wood referenced "one of the best long-term studies" giving 10 grams per day with resistance training and showing benefit for bone health. This appears to reference real published research (a Canadian trial), but the bone-health findings from creatine research are mixed overall. The cognitive benefits Wood mentioned for creatine in older adults are supported by some but not all trials — the evidence is promising rather than settled.

No claims rise to the level of clearly false.

Why this matters for you

• Check your iron and homocysteine. Wood specifically flagged that roughly 10% of midlife women are iron deficient and that low iron is associated with cognitive decline and more pronounced menopausal cognitive changes. Homocysteine — elevated when B12, folate, B6, or B2 are low — is a well-established dementia risk marker. Both are standard blood tests. If you haven't had them checked recently, ask your doctor, especially if you're a woman in or near menopause.
• The exercise prescription is specific. Aerobic exercise and resistance training affect different parts of the brain and support different cognitive functions. Doing only one is leaving something on the table. Wood's suggested minimum — two to three aerobic sessions per week plus one to two strength sessions, with at least one aerobic session involving higher