Every few years, the world's leading dementia researchers recount the risk factors and conclude more of the disease is preventable than they said last time. The number has now reached 45%. In its 2024 report, the Lancet Commission on Dementia Prevention, Intervention, and Care concluded that approximately 45% of dementia cases worldwide could be prevented or delayed by addressing 14 modifiable risk factors across the life course. The Commission synthesizes the global evidence into consensus guidance. Its first report, in 2017, identified 9 risk factors. The 2020 update expanded the list to 12 and put the preventable share at 40%. The 2024 update added untreated vision loss and high LDL cholesterol, and the figure rose again. Nearly half of it, on the best current evidence, does not have to happen.
Hold the number at arm's length, though: 45% is a population attributable fraction — the theoretical ceiling if every person eliminated every risk factor simultaneously. No individual gets to claim it as a personal guarantee, and about 55% of cases are not attributable to the known modifiable factors at all. The honest translation is better odds, not immunity. But the direction of travel matters, as does Professor Gill Livingston's refrain — it is never too early and never too late to start protecting your brain.
The biggest lever sits in your ears
The 2024 report's surprise is which factor sits at the top. Midlife hearing loss accounts for an estimated 7% of dementia cases — more than hypertension, smoking, obesity or physical inactivity individually, and tied with high LDL cholesterol as the single largest factor. Most people file hearing under comfort or vanity. The Commission files it under brain health.
Why it matters is still being untangled: degraded auditory input may directly burden cognitive processing; hearing loss drives social withdrawal, itself on the list; and the two may share vascular causes. What makes the finding actionable is that, unlike most items on the list, hearing loss is treatable today — UCL researchers are studying personalized hearing support specifically as a brain-health intervention. If you find yourself turning up the volume, asking people to repeat themselves, or going quiet in noisy rooms, a hearing test is not vanity. On the Commission's data, it may be one of the highest-value preventive steps available.
Step back. The largest items are not exotic: sensory (hearing loss at 7%, untreated vision loss newly added in 2024), vascular (cholesterol at 7%, hypertension, diabetes) and social (isolation at 5%). Almost everything at the top is treatable or manageable with tools already in primary care. The biggest known levers on dementia are not waiting for a pharmaceutical breakthrough; they are sitting in audiology clinics, GP surgeries and community halls, underused. The science is ahead of the delivery.
Heart health is brain health
A striking share of the 14 factors are cardiovascular: hypertension (2%), diabetes (2%), smoking (2%), obesity (1%), excessive alcohol (1%) and high LDL cholesterol (7%). What damages blood vessels damages cognition — through strokes large and silent, impaired clearance of metabolic waste, and chronic under-perfusion of brain tissue.
Timing matters: blood pressure, blood sugar, cholesterol and weight measured in your 40s through 60s predict dementia risk decades later more strongly than the same measurements in old age. The midlife window is the high-leverage one; the prescription is managing the vascular risks your doctor already monitors, because every one of them is a brain risk factor too.
Physical inactivity accounts for about 2% of cases in the Commission's model, but the broader literature suggests a larger protective effect: systematic reviews link regular physical activity with roughly 20% lower risk of dementia. Aerobic exercise increases blood flow to the brain and stimulates brain-derived neurotrophic factor (BDNF), supporting neuron growth and survival, while functional strength training adds metabolic benefits and fall prevention — falls being a route to traumatic brain injury, another of the 14 factors. OmniWire's look at Zone 2 cardio and VO2 max benchmarks makes the same point. Consistency matters more than type: benefits accrue to people who keep moving, not to people who train intensely for a month and stop.
Greens, berries, and a 53% figure
Few findings in nutritional neuroscience have travelled as far as the MIND diet — the Mediterranean-DASH Intervention for Neurodegenerative Delay, developed in 2015 by Martha Clare Morris and colleagues at Rush University Medical Center in Chicago. It emphasizes ten brain-healthy food groups — green leafy vegetables, other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil, and wine in moderation — and limits five: red meat, butter and stick margarine, cheese, pastries and sweets, and fried and fast food.
Among 923 Rush participants aged 58 to 98, followed for an average of 4.5 years, those in the highest third of MIND adherence had a 53% lower rate of Alzheimer's disease (hazard ratio 0.47) than the lowest third. Even moderate adherence was associated with about 35% lower risk (HR 0.65) — distinguishing MIND from the Mediterranean and DASH diets, where only the highest adherence showed benefit. In a separate analysis of 960 Rush participants followed for 4.7 years, the most adherent eaters tested as the cognitive equivalent of 7.5 years younger than the least adherent.
These are observational results, though, and a 2023 randomized clinical trial produced more nuanced results than the early cohort studies suggested. As Today's Dietitian's 2026 review put it, the evolution from early promise to mixed trial data shows the promise and complexity of "food as medicine." The proposed mechanisms remain plausible — polyphenols and flavonoids from berries reducing oxidative stress and neuroinflammation, folate and lutein from leafy greens, lower saturated fat protecting cerebral blood vessels. Promising, plausible, not yet proven at the highest standard.
Sleep, friends, and the rest of the list
Sleep is not one of the Commission's 14 factors, but researchers increasingly place it in the same picture. During deep sleep, the brain's glymphatic system — a waste-clearance network discovered in the last decade — becomes more active, flushing metabolic byproducts including the amyloid proteins associated with Alzheimer's pathology. Chronic short sleep and sleep apnea, which fragments sleep architecture, have both been linked in observational studies to higher dementia risk. The practical guidance: 7–9 hours, a consistent schedule, suspected sleep apnea evaluated, and the morning-light and evening-darkness cues that stabilize circadian rhythm protected.
Two of the 14 factors live in the social-emotional domain: social isolation (5% of cases, the largest later-life factor) and depression (3%). Conversation, empathy and social navigation are among the most complex computations the brain performs, and withdrawing from them appears to accelerate decline. Depression may act directly, through chronic stress hormones, and indirectly, by sapping motivation for exercise, social contact and other protective behaviours — one reason mindfulness-based approaches to chronic anxiety and stress attract research attention here. The prescription: maintain friendships, participate in community life, volunteer, and treat depression as the medical condition it is.
Traumatic brain injury accounts for about 3% of cases, spanning road accidents, sports concussions and falls in older adults; helmets, seatbelts, fall-proofing the home and honest assessment of contact-sport risks are all brain-health measures. Air pollution accounts for another 3% — the factor least under individual control. Fine particulate matter appears to reach the brain via the olfactory system and the bloodstream, driving neuroinflammation; home filtration and attention to air-quality indices help at the margins. Education completes the list: less education in early life accounts for 5% of cases, the largest early-life factor, because schooling builds the cognitive reserve that lets a brain function normally despite accumulating damage. Reserve-building does not stop at graduation: learning new skills, reading, complex work and bilingualism are all associated with slower decline. What the Commission's evidence favours is real-world engagement — not commercial brain-training games, whose benefits have not been shown to transfer to everyday cognition.
Fourteen factors can feel overwhelming. Clustered, they are familiar virtues: get hearing and vision checked; keep blood pressure, cholesterol, blood sugar and weight in healthy ranges; exercise regularly; eat leafy greens and berries more often and fried food less; don't smoke; moderate alcohol; stay socially engaged; treat depression; protect your head; keep learning. None of it requires a biohacking budget. And is it too late in your 60s or 70s? No. Midlife is the highest-leverage window for vascular factors, but social engagement, exercise, hearing and vision correction, and diet changes all show benefits when adopted later. The actions span the whole life course. Starting late still beats never starting.
As a timeline, the 14 factors map a life: education (5%) is the early-life entry; the vascular cluster and hearing loss dominate midlife, which is why the Commission keeps pointing at the 40s through 60s as the window where intervention buys the most; social isolation (5%) and depression (3%) weigh heaviest later. Treat brain health as a portfolio rather than a product: no item promises much alone — a percentage point here, two there. Stacked across a life course, they are the difference between the 45% that might be prevented or delayed and the share that simply happens to a brain. Hearing checked. Blood pressure managed. Legs moving. People around you. It has never sounded like a breakthrough. On the numbers, it is one.
Disclaimer: This article is for informational purposes only and is not medical advice. Discuss dementia risk factors and any major lifestyle changes with your healthcare provider.
The field's biggest honour this year went to optogenetics, the algae protein that became a light switch for the brain, winning the Nobel Prize in Medicine.
Daily habits protect the brain through systems people underestimate, starting with the night: sleep architecture — in particular the deep non-REM hours — tracks closely with cognitive resilience. Nutrition timing runs a close second; the evidence on time-restricted feeding, NAD+ precursors and autophagy separates what the protocols can show from what promoters claim.
Sources
- The 2024 Lancet Commission on dementia prevention, intervention, and care — 14 modifiable risk factors, ~45% preventable (UCL summary): ucl.ac.uk
- The Lancet Commission on Dementia Prevention — full factor breakdown by life stage: mindr.us
- What the 2024 Lancet Commission found — analysis of the 45% figure and its limits: thememoryshield.com
- Morris et al. 2015 — MIND diet and Alzheimer's incidence (923 participants; HR 0.47 high adherence, 0.65 moderate): alz-journals.onlinelibrary.wiley.com
- MIND diet and 7.5-years-younger cognitive aging (Rush Memory and Aging Project, 960 participants): inverse.com
- Nuance in "Food as Medicine" — MIND diet RCT results and evolving evidence (Today's Dietitian, 2026): todaysdietitian.com
- MIND diet components and adherence guidance (Rush University, via Medscape): medscape.com
- World Alzheimer's Month 2026 — Lancet Commission awareness summary (Lanka Alzheimer's Foundation): corpcom.lk
