17 Brain-Health Factors: 14 Established Risks + 3 Exploratory Domains

Chronological age does not fully describe variation in brain structure, function, or cognitive health. In research, MRI-based models can estimate a brain-age gap from neuroimaging data. A self-report questionnaire is different: it can organize modifiable health and lifestyle factors, but it cannot inspect the hippocampus, cortical thickness, cerebral perfusion, or white-matter integrity.

§I.What brain age means — and what a questionnaire cannot measure

In neuroimaging research, the brain-age gap is the difference between chronological age and a model’s estimate based on brain scans. Large cohort studies have associated older-appearing MRI patterns with later health outcomes, but the estimate is probabilistic, model-dependent, and not a diagnosis or destiny. It should not be confused with a score derived from self-reported risk factors.

The LBL Brain Age Index does not reproduce MRI-derived brain age. It is a LifeByLogic original exploratory instrument that organizes 14 Lancet risk domains and three additional research domains into an educational profile. Its composite “brain-age” label is a communication device from the tool’s own scoring model — not a validated biological-age measurement or an individual dementia-risk estimate.

§II.The 2024 Lancet Commission's 14 modifiable risk factors

In July 2024, The Lancet published an updated report from its Standing Commission on Dementia Prevention, Intervention, and Care. The 2024 update expanded the previous (2020) list from 12 risk factors to 14, adding untreated vision loss and elevated LDL cholesterol based on accumulated longitudinal evidence the earlier report lacked. The Commission's headline claim:

"An estimated 45% of dementia cases worldwide could be prevented or delayed by addressing 14 modifiable risk factors across the life course." — Livingston et al., The Lancet 404:572–628, 2024

The 14 factors, grouped by the life stage in which they exert their largest effect:

Three things are worth understanding about how this list was built. First, these are Population Attributable Fractions (PAFs), not individual risk predictions. The 45% figure is what you'd theoretically prevent if every modifiable factor were optimally addressed across every person in a population. Your individual risk depends on which factors apply to you and at what magnitude. Second, the factors are not independent — hypertension, LDL, diabetes, and obesity cluster as a cardiovascular package. Third, the list is deliberately conservative: the Commission only included factors with strong meta-analytic evidence for a causal-pathway claim.

The LBL Brain Age Index can help readers reflect on which domains may warrant attention. It does not apply population attributable fractions as personalized weights, and it does not convert the Commission’s population estimates into an individual probability.

§III.What the Commission got right

The 2024 Commission is a widely cited international framework for dementia prevention, care, and public-health planning. Three features are especially useful when its population estimates are kept separate from individual prediction.

Population attributable fractions provide a useful public-health frame. They estimate how much disease burden is associated with a factor across a population under explicit assumptions. They do not reveal what caused one person’s outcome, and they cannot identify a single intervention that will change an individual trajectory.

The 2024 additions — vision and LDL — are well-supported. Untreated vision loss had been suggested as a risk factor in 2020 but lacked the meta-analytic backing. The 2024 update added it based on stronger longitudinal evidence, including data showing that cataract surgery is associated with reduced dementia incidence. Elevated LDL cholesterol was added based on multiple cohort studies showing dose-response relationships independent of cardiovascular events. Both additions are conservative; neither is overstated.

The life-stage grouping is useful. What matters at age 30 is not what matters at 70. The Commission's life-stage framing reflects this: early-life education builds cognitive reserve that pays off decades later; mid-life cardiovascular control prevents small-vessel disease; late-life sensory and social factors compound the effects of accumulated damage. The framework respects the biology of timing.

This consensus framework is the foundation. The next section separates the 14 established Lancet factors from three additional domains included only as exploratory context.

§IV.Three additional exploratory brain-health domains

Sleep, later-life cognitive activity, and chronic psychological stress are relevant to brain-health research, but they are not three independent additions to the Lancet Commission’s consensus list. Their definitions overlap with other factors, much of the evidence is observational, and their population-level causal contributions are not established well enough to assign Lancet-equivalent weights.

1. Sleep duration, regularity, timing, and quality. Adequate sleep supports cognitive function, while irregular or disrupted sleep is associated with adverse health outcomes. A 2025 UK Biobank analysis found that device-measured sleep regularity and duration were associated with incident dementia risk, but observational associations do not establish that changing one sleep metric will prevent dementia. Sleep is therefore included here as an exploratory behavioral domain, not as a fifteenth Lancet factor. See sleep regularity and brain health.

2. Sustained cognitive activity across adulthood. Consensus reserve frameworks distinguish early-life education from cognitive reserve and brain maintenance across the lifespan. Mentally demanding work, learning, and social engagement may contribute to resilience, but no questionnaire can translate a specific activity into a guaranteed reduction in dementia risk. This domain extends the discussion beyond credentials without replacing the Commission’s education factor. See what cognitive reserve means.

3. Chronic psychological stress. A 2021 systematic review and meta-analysis found associations between adult psychological stress and later mild cognitive impairment or dementia, while also emphasizing heterogeneity and the need for stronger causal evidence. Stress is clinically important and may affect brain health through several pathways, but it is not currently a separate Lancet consensus risk factor. See allostatic load.

The LBL Brain Age Index includes these three as explicitly exploratory domains. Their scores are not equivalent to Lancet population attributable fractions and should not be summed into a personal dementia-risk percentage.

§V.The cardiovascular cluster: how your heart ages your brain

Five of the Lancet 14 are cardiovascular: hypertension, high LDL, diabetes, obesity, and physical inactivity. They cluster because they share a single downstream pathway — cerebral small-vessel disease. Chronic elevation of blood pressure and blood glucose damages the cerebral microvasculature over years, reducing perfusion to deep white matter and the hippocampus. This is the same mechanism that drives stroke, but operating at sub-clinical levels for decades before any acute event.

What this means practically is that mid-life cardiovascular control is one of the highest-leverage interventions in the entire framework. The 40–65 window matters more than the 65+ window because the damage during mid-life is what determines the baseline for late-life decline. A person whose blood pressure has been well-controlled from age 45 onward enters their seventies with a structurally different brain than someone whose blood pressure ran 15 mmHg high for thirty years.

Three honest things follow:

• Blood pressure targets matter more than once-yearly readings. A single high reading is data. Sustained elevation, especially nocturnal, is the actual risk.
• LDL is now in the framework. This is the 2024 addition. Statins are not the only path to LDL control — diet and exercise produce measurable effects — but for individuals with familial elevation, pharmacologic management is appropriate.
• The metabolic cluster is unified. Diabetes, obesity, and inactivity feed into the same pathway. Tools that address them as a system (rather than as separate problems) tend to outperform.

The Brain Age Test asks about all five cardiovascular domains. Its output uses an exploratory LifeByLogic scoring model; Lancet population attributable fractions are not converted into personal weights.

§VI.The sensory cluster: hearing, vision, and "use it or lose it"

Hearing loss is one of the largest single-factor risks in the Lancet framework, with a Population Attributable Fraction of approximately 7%. Vision loss, added in 2024, contributes another ~2%. Together, the sensory cluster accounts for roughly 9% of population-level dementia risk — more than smoking, more than physical inactivity, more than air pollution.

Why does sensory loss accelerate cognitive aging? Two mechanisms. First, sensory deprivation reduces cortical input, leading to measurable thinning in primary sensory cortex, which then propagates to adjacent association areas. Hearing loss patients show accelerated atrophy in the temporal lobe; vision loss patients show it in occipital and parietal regions. Second, the cognitive cost of effortful perception under degraded input crowds out resources for memory encoding (the "cognitive load" hypothesis of Pichora-Fuller and colleagues). Someone straining to follow a conversation in noise has less attention available to remember what was said.

The intervention evidence is exceptionally strong. The ACHIEVE trial (Lin et al. 2023) found that hearing aids reduced cognitive decline by up to 8% in adults with measurable hearing loss. Cataract surgery has been associated with reductions in dementia incidence in multiple longitudinal cohorts. These are among the highest-effect-size interventions in the entire prevention literature, and they are routinely underused.

The Brain Age Test explicitly captures hearing and vision status. Most consumer brain-age tools don't — and you should be skeptical of any tool that doesn't ask.

§VII.The lifestyle-cognitive cluster: sleep, exercise, social, stimulation

The factors with the most agency for the average reader: physical activity, sleep, social engagement, and cognitive stimulation. These are where individual behavior change produces the most measurable difference in absolute terms.

Physical activity. The Lancet uses the WHO threshold of 150 minutes per week of moderate-intensity activity. Mechanism includes upregulation of brain-derived neurotrophic factor (BDNF), increased cerebral blood flow, and direct neurogenic effects in the hippocampus. The intervention dose-response is well-characterized; even modest increases above sedentary produce measurable effects.

Sleep. The Commission treats sleep tangentially (see §IV). The LBL-BAI captures both duration and quality as separate inputs, because they predict different things. Short sleep predicts cardiometabolic outcomes; poor sleep architecture predicts cognitive outcomes. Cross-link: Sleep Schedule Calculator, sleep-need calculator.

Social engagement. Loneliness is itself a risk factor, separate from objective isolation — two people can have identical social contact frequencies and report very different loneliness. The mechanism is partly inflammatory (chronic loneliness is associated with elevated CRP and IL-6) and partly cognitive-stimulation-related (social interaction is among the most cognitively complex activities humans engage in). Cross-link: Loneliness Test, loneliness.

Cognitive stimulation. An exploratory LBL domain. Not "do crosswords"; not "read more newspapers." The relevant signal is novel cognitive demand — engaging with material outside your existing competence in a way that requires sustained effort. Learning a new instrument. Studying an unfamiliar field for ninety days. Picking up a language. Adults retain capacity for learning-related neuroplastic change, but the evidence does not support assigning a fixed dementia-risk reduction to any particular cognitive activity.

§VIII.How to explore your modifiable brain-health profile

The LBL Brain Age Index is a LifeByLogic original exploratory instrument covering 17 self-reported domains: the 14 Lancet factors plus sleep, sustained cognitive activity, and chronic stress.

It provides:

• An educational summary of the 17 domains covered by the questionnaire
• A relative pattern showing which self-reported areas may deserve closer attention
• Links to supporting evidence and practical follow-up resources

The interface may express its composite as a “brain-age” estimate. That number comes from the tool’s own exploratory scoring model; it is not MRI brain age, a validated biological-age measurement, a clinical assessment, or an individual dementia-risk calculation. Completion is browser-local, with no email gate or stored response data.

Explore your brain-health profile →

§IX.Five practical priorities supported by the evidence

These are broad public-health priorities, not a personalized ranking and not a treatment plan. The most appropriate action depends on age, medical history, access, and which factors actually apply.

1. Know and manage blood pressure with a clinician. Midlife hypertension is an established modifiable dementia-risk factor and an important cardiovascular target.
2. Address hearing difficulty. In the ACHIEVE randomized trial, hearing intervention did not change three-year global cognition in the overall cohort; a prespecified higher-risk subgroup showed slower decline. Hearing care still improves communication and quality of life even when cognitive benefit is uncertain.
3. Stay physically active within your abilities. Regular activity supports cardiovascular health and is part of major dementia-risk-reduction guidance; the safe type and intensity are individual.
4. Protect adequate, regular sleep. Duration, regularity, timing, and quality are distinct. Observational studies support attention to all four, but no single schedule rule has been proved to prevent dementia.
5. Keep learning and stay socially engaged. Cognitive and social activity are associated with reserve and healthier aging, while the size and causal direction of their effects remain difficult to isolate.

Use the exploratory profile to organize questions, not to identify which factors are “damaging” a particular brain. Medical risk factors such as hypertension, diabetes, hearing loss, depression, and sleep disorders should be assessed and managed with qualified professionals.