How old is your brain?
The Brain Age Index estimates your brain's biological age from 17 evidence-based factors — built on the 2024 Lancet Commission on Dementia Prevention and MRI Brain Age Gap research from the UK Biobank (n > 38,000).
Answer honestly.
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How the Brain Age Index is calculated.
The LifeByLogic Brain Age Index (LBL-BAI) is a weighted composite score combining 17 evidence-based factors that have been shown in peer-reviewed neuroscience literature to predict the brain age gap — the difference between an individual's chronological age and their estimated biological brain age as derived from MRI or clinical biomarkers.
Its two primary research foundations are:
Each factor contributes a weighted adjustment (in years) to the individual's chronological age. The weights reflect published population attributable fractions (PAFs), effect sizes from cohort studies, and MRI-derived brain age gap associations. Sleep and chronic stress — not in the Lancet 2024 factor list — are included because of their well-established association with MRI-measured brain age acceleration.
Factor Weights & Sources
Note: The Brain Age Index is an educational tool designed to surface modifiable areas of lifestyle and health. It is not a medical diagnosis. For clinical assessment of cognitive health, consult a healthcare provider.
The research behind the index.
- Livingston G, Huntley J, Liu KY, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet. 2024;404(10452):572-628. doi:10.1016/S0140-6736(24)01296-0
- Stoitsas K, Bakx P, Voortman T, Yu J, Roshchupkin G, Bos D. Contributions of lifestyle, education, and cardiovascular risk factors to the brain age gap. Aging Brain. 2025. doi:10.1016/j.nbas.2025.100149
- Brain Age Acceleration on MRI Due to Poor Sleep: Associations, Mechanisms, and Clinical Implications. 2025 systematic review across > 25,000 participants. PMC12730621.
- Brain age gap as a predictive biomarker that links aging, lifestyle, and neuropsychiatric health. Communications Medicine. 2025. Analysis of UK Biobank (n=38,967), ADNI (n=1,402), and PPMI (n=1,182) cohorts.
- Stephan BCM, et al. Population attributable fractions of modifiable risk factors for dementia: a systematic review and meta-analysis. The Lancet Healthy Longevity. 2024;5(6):e406-e421.
- A physically and mentally active lifestyle relates to younger brain and cognitive age. GeroScience. 2025. Cohort study n=211 cognitively unimpaired older adults.
- Mostert CM, et al. Broadening dementia risk models: building on the 2024 Lancet Commission report for a more inclusive global framework. eBioMedicine. 2025.
- The potential for dementia prevention in Brazil: a population attributable fraction calculation for 14 modifiable risk factors. Lancet Regional Health Americas. 2025. ELSI-Brazil cohort (n=9,949).
Questions about the index.
Brain age is an estimate of your brain's biological state — how well it has aged compared to your chronological age. In research settings, it's measured via MRI scans analyzed by machine learning models trained on large populations. The brain age gap is the difference between your chronological age and your estimated brain age: a negative gap means your brain looks younger than your years, a positive gap means it's aging faster.
This is an educational estimate, not a medical diagnosis. It's calibrated against published population-level research, but individual accuracy varies. MRI-based brain age models in validation cohorts have mean absolute errors of 2.4-2.5 years. Questionnaire-based estimates like this one are less precise but capture the most important modifiable levers identified across over 1 million research participants.
Yes — and this is the whole point. The 2024 Lancet Commission estimates that addressing the 14 modifiable factors could prevent or delay 45% of dementia cases globally. The most impactful levers are hearing correction, LDL cholesterol management, physical activity, sleep quality, smoking cessation, and social engagement. Your "Top 3 factors aging your brain" panel is designed to show you exactly where to focus.
Hearing loss has the largest population attributable fraction in the Lancet 2024 report (7%). The current leading hypothesis is that uncorrected hearing loss increases cognitive load, reduces social engagement, and may accelerate brain atrophy in the auditory cortex. The good news: hearing aids mitigate most of this risk.
No. Every calculation runs locally in your browser using JavaScript. Nothing you enter is sent to our servers, stored in a database, or used for tracking. You can verify this by opening your browser's developer network tab while using the tool.
The Lancet Commission focuses specifically on dementia risk factors with established causal evidence. Sleep and chronic stress are both strongly linked to MRI-measured brain age acceleration — a closely related but distinct outcome. A 2025 systematic review found that suboptimal sleep independently predicts 1-3 years of brain age acceleration across over 25,000 participants. We include these because the tool measures brain age, not just dementia risk.