Brain Health

Up to 45% of dementia risk is attributable to modifiable factors (Lancet Commission 2024). The single most important framing shift in modern dementia prevention is that the brain is downstream of cardiovascular and metabolic health — not a separate organ. What's good for the heart is overwhelmingly good for the brain.

What the evidence actually supports

Strong (Lancet Commission 2024 — modifiable risk factors, ranked roughly by population attributable fraction):

1. Hearing loss (largest single modifiable factor) — treat with hearing aids; the ACHIEVE trial (2023) showed reduced cognitive decline in high-risk older adults. See Hearing for the 2026 ASPREE target trial emulation cutting 7-year dementia risk from 7.5% to 5.0%, why standard audiometry misses early damage, and the noise × air-pollution synergy.
2. Hypertension — treat aggressively, especially mid-life. SPRINT-MIND showed lower MCI/dementia incidence with intensive BP control.
3. Smoking — quit at any age; cognitive trajectory improves.
4. Obesity — particularly visceral; metabolic syndrome strongly predicts late-life dementia.
5. Type 2 diabetes — well-controlled diabetes ≠ uncontrolled diabetes for cognitive outcomes.
6. Physical inactivity — exercise is the single strongest behavioral lever; aerobic and resistance both contribute.
7. Depression — both a risk factor and a prodrome; treat regardless.
8. Social isolation — strong cohort signal; the "loneliness epidemic" is a measurable risk.
9. Lower educational attainment (early life) — cognitive reserve.
10. Excessive alcohol — even moderate use is now considered risk-elevating.
11. Air pollution (PM2.5) — chronic exposure raises dementia incidence.
12. Traumatic brain injury — repeated subconcussive impacts (contact sports) carry signals.
13. Visual impairment (newly added 2024) — uncorrected visual loss compounds isolation and reduces stimulation. See Vision for the Retinal Age Gap, lutein and macular pigment, the 670 nm red-light finding, and why blue-light-blocking glasses don't move sleep or eye-strain endpoints.
14. High LDL cholesterol (newly added 2024) — vascular contribution.

Moderate:

• MIND diet adherence — observational signal of ~53% reduction in Alzheimer's at highest tertile (Morris 2015). The MIND-USDA RCT (2023) was less impressive but still favorable.
• Sleep architecture — slow-wave sleep clears beta-amyloid via the glymphatic system. Chronic short sleep predicts dementia.
• Cognitive engagement — language learning, music, complex hobbies; ACTIVE trial showed durable training effects.

Weak / preliminary:

• Specific supplements for cognition (omega-3, B vitamins, ginkgo, curcumin) — most show null or inconsistent results in RCTs.
• "Brain training" apps — small, narrow effects with limited transfer to general cognition.

The integrated, multidomain approach to acting on this list — the FINGER trial, cardiovascular risk reduction as the core engine of cognitive protection, and what individuals can actually do across all fourteen factors — is collected under Dementia prevention.

Practical brain-health checklist

1. Treat hearing loss. If you suspect any hearing decline, get audiometry. Hearing aids are not vanity — they may be one of the single most impactful interventions for cognitive aging. If you struggle in noisy environments but pass a standard audiogram, ask for extended high-frequency (EHF) audiometry — it captures ~64% of age-related variance in real-world speech understanding vs. the standard test's ~16%. See Hearing.
2. Get a comprehensive dilated eye exam at midlife and treat any correctable visual loss. Cataract surgery, glasses, low-vision rehabilitation, and AMD management protect the sensory bandwidth that maintains cognitive engagement. Ask about OCT and OCT-angiography — these are the imaging modalities feeding the new oculomic biomarkers (Retinal Age Gap, AI-derived cardiovascular risk). Eat the macula: leafy greens daily for lutein and zeaxanthin. See Vision.
3. Treat hypertension aggressively in midlife. Systolic <130 if tolerated.
4. Stay metabolically healthy. Avoid type 2 diabetes; treat insulin resistance.
5. Train both ways. Aerobic and resistance exercise both have independent effects on hippocampal volume and cognitive function.
6. Sleep well. 7–8 hours, regular schedule, screen for OSA.
7. Eat MIND-pattern. Leafy greens daily, berries 2+ times/week, fish, nuts, olive oil, whole grains, beans, poultry. Limit red meat, butter/stick margarine, cheese, fried foods, sweets.
8. Stay socially connected. Real-world relationships, regular interaction. The strongest single behavioral predictor in cohort data.
9. Stay cognitively engaged. Learning new skills, languages, music. Use it or lose it has biological reality (cognitive reserve).
10. Don't smoke; drink minimally; reduce air pollution exposure where feasible (HEPA filtration in homes near major roads is a small, plausible win).
11. Wear seatbelts and helmets; avoid repeated head impacts (contact sports).

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