Dementia Prevention and Brain Health: A Narrative Review of Global Burden, Modifiable Risk Factors, Evidence-Based Interventions, and Public Health Implications for Low-, Middle-, and High-Income Countries, 2024–2026.

 Dementia Prevention and Brain Health: A Narrative Review of Global Burden, Modifiable Risk Factors, Evidence-Based Interventions, and Public Health Implications for Low-, Middle-, and High-Income Countries, 2024–2026

Authors: Dr. Shekhar, Rajesh MPH and Team, Doctor's Forum For All 🏥⚖️

Disclaimer

This article is strictly for educational purposes only. It does not constitute medical advice or a substitute for professional clinical judgment. Readers should consult qualified healthcare providers for specific recommendations. The authors and Doctor's Forum For All 🏥⚖️ disclaim any liability for actions taken based on this content. All data cited are from publicly available sources as of the date of publication. The views expressed are those of the authors alone.

Abstract

Background: Dementia is the seventh leading cause of death globally, affecting more than 57 million people, with nearly 10 million new cases diagnosed each year. The 2024 Lancet Commission identified 14 modifiable risk factors accounting for up to 45% of dementia cases, and the WHO released updated risk reduction guidelines in July 2026. This review examines the evidence for dementia prevention and its implications for public health policy and clinical practice.

Methods: We conducted a narrative synthesis of the 2024 Lancet Commission report, WHO 2026 guidelines on risk reduction of cognitive decline and dementia, Global Burden of Disease 2021 data, systematic reviews and meta-analyses of multidomain lifestyle interventions including the FINGER trial, cost-effectiveness analyses, and implementation studies from primary care settings in India and other low- and middle-income countries.

Results: Global dementia prevalence exceeded 57 million in 2025, with projections reaching 139 million by 2050. More than 60% of people with dementia live in low- and middle-income countries. The 2024 Lancet Commission identified 14 modifiable risk factors across the life course, including less education, hearing loss, hypertension, obesity, smoking, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury, air pollution, social isolation, untreated vision loss, and high LDL cholesterol. The FINGER trial demonstrated that a 2-year multidomain intervention combining diet, exercise, cognitive training, social activity, and vascular risk monitoring significantly improved cognitive function in at-risk older adults. A Cochrane review of 9 randomized controlled trials with 18,452 participants found a small positive effect of multidomain interventions on global cognition (Z-score mean difference 0.03, 95% CI 0.01–0.06). Cost-effectiveness analyses from England estimated that population-level interventions, including low emission zones and sugar reduction, could generate savings of £260 million and £1.05 billion respectively. India's SMRUTHI-India trial is testing a multimodal care bundle approach for primary prevention in at-risk elderly populations.

Conclusion: Dementia is not an inevitable part of ageing. Nearly half of all cases may be preventable or delayable through targeted risk reduction. The evidence supports multidomain lifestyle interventions, population-level policies addressing air pollution and cardiovascular risk factors, and integration of brain health into primary care. Health leaders must translate this knowledge into action through national dementia plans, primary care capacity building, and sustained investment in prevention. The window for meaningful intervention is open. It will not stay open indefinitely.

Keywords: dementia prevention, brain health, modifiable risk factors, multidomain interventions, FINGER trial, WHO guidelines, Lancet Commission, public health, cognitive decline

Introduction

Dementia is not a normal part of ageing. That is the first thing the World Health Organization wants people to understand. It is a syndrome caused by diseases that damage the brain. It affects memory, thinking, behaviour, and the ability to perform everyday tasks. It is progressive. It is currently incurable. And it is becoming more common.

More than 57 million people live with dementia worldwide. Nearly 10 million new cases are diagnosed each year. By 2050, that number is projected to reach 139 million. The economic cost is staggering. Dementia costs the global economy $1.3 trillion annually, with approximately half of that representing unpaid care provided by family members and friends.

The burden is not evenly distributed. More than 60% of people with dementia live in low- and middle-income countries, and that proportion is expected to rise to 71% by 2050. In India, prevalence among adults aged 60 years and older ranges from 4.5% to 11% across states, with higher burden influenced by education, lifestyle, and healthcare access. In Latin America, prevalence among people aged 65 and older is estimated at 8–10%, representing 8 million cases in 2025 and a projected 20 million by 2050—a 205% increase.

For decades, the narrative around dementia was one of inevitability. You get older, your brain declines, and there is nothing you can do about it. That narrative is now outdated. The science has moved.

In July 2024, the Lancet Commission on dementia prevention, intervention, and care published its third major report. It identified 14 modifiable risk factors across the life course that account for up to 45% of dementia cases worldwide. The commission estimated that nearly half of all dementia cases could be prevented or delayed by addressing these factors. That is not a small finding. It is a paradigm shift.

The 14 risk factors are: less education, hearing loss, hypertension, obesity, smoking, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury, air pollution, social isolation, untreated vision loss, and high LDL cholesterol. Two of these—high LDL cholesterol and untreated vision loss—were added in the 2024 update, reflecting new evidence about their contribution to dementia risk.

In July 2026, the WHO released its second edition of guidelines on risk reduction of cognitive decline and dementia. The guidelines reflect a life-course understanding of dementia risk, recognizing that exposure to risk factors accumulates over time and that certain risk factors may have greater impact at specific life stages. They cover interventions addressing 20 potentially modifiable risk factors in four categories: promoting healthy behaviours, managing physical health conditions, addressing environmental risk factors, and implementing tailored multidomain interventions.

The WHO guidelines make several new recommendations. Cognitive stimulation and training may be encouraged for adults with mild cognitive impairment. Engagement in social activity interventions may be recommended for adults with normal cognition or mild cognitive impairment. Physical activity should be recommended. Air pollution is now officially recognized as a dementia risk factor.

These are not abstract policy documents. They are practical, evidence-based guidance that countries can implement immediately. Dr. Tedros Adhanom Ghebreyesus, WHO Director-General, said it plainly: "We know more today than ever before about what drives dementia risk, and these guidelines translate that knowledge into action. Countries now have clear, evidence-based recommendations they can put into practice immediately to protect people's cognitive health".

This article examines dementia prevention and brain health through four questions. First, what is the global burden of dementia, and how is it distributed? Second, what are the modifiable risk factors and the evidence supporting their role in prevention? Third, which interventions have demonstrated effectiveness in clinical trials and real-world settings? Fourth, what are the implications for public health policy, clinical practice, and health system design?

The article is written for health professionals, public health practitioners, policymakers, and informed readers. It argues that dementia prevention is one of the most significant opportunities in global health today. The evidence is strong. The tools are available. The cost of inaction is measured in millions of families navigating a disease that could have been delayed.

The window for meaningful intervention is open. It will not stay open indefinitely.

Methods and Materials

Study Design: This article is a narrative synthesis of published policy documents, peer-reviewed literature, clinical trial evidence, and implementation case studies. It is not a systematic review.

Setting and Population: The scope is global, with emphasis on low- and middle-income countries where the majority of people with dementia live and where prevalence is projected to rise fastest. Data sources reflect populations of older adults, midlife adults, and caregivers affected by cognitive decline and dementia.

Data Sources: The primary data sources were the 2024 Lancet Commission on dementia prevention, intervention, and care (Livingston et al., The Lancet, 2024); the WHO Risk Reduction of Cognitive Decline and Dementia: WHO Guidelines, Second Edition (2026); WHO dementia fact sheets and surveillance data; the Global Burden of Disease Study 2021 analysis of Alzheimer's disease and other dementias; the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) randomized controlled trial (Ngandu et al., The Lancet, 2015); a Cochrane systematic review of multidomain interventions for dementia prevention (9 RCTs, 18,452 participants); cost-effectiveness analyses published in The Lancet Healthy Longevity (2024); the SMRUTHI-India multimodal care bundle trial protocol; and WHO and Alzheimer's Disease International reports on national dementia plans and Global Action Plan extension to 2031.

Variables and Measurements: Dementia burden was measured using prevalence estimates, incidence rates, mortality data, and disability-adjusted life years (DALYs) from WHO and GBD sources. Risk factors were assessed through the Lancet Commission's population attributable fraction (PAF) methodology. Intervention effectiveness was assessed through reported cognitive outcomes, including Z-score mean differences, risk ratios, and changes in neuropsychological test performance. Cost-effectiveness was assessed through reported cost savings and quality-adjusted life years (QALYs) gained.

Statistical Analysis: No primary statistical analysis was conducted. Published figures and effect sizes are reported as cited.

Ethical Considerations: This article uses only publicly available policy documents, de-identified aggregate data, and published literature. No primary data collection involving human subjects was conducted. Institutional review board approval was not required.

Results

Global Burden of Dementia

Dementia is the seventh leading cause of death globally and a major cause of disability and dependency among older people. In 2021, the Global Burden of Disease study recorded 9.84 million incident cases of Alzheimer's disease and other dementias, with 1.95 million dementia-related deaths, causing 36.33 million DALYs globally.

The geographical distribution of dementia is shifting. While high-income countries currently have higher age-standardized prevalence, the absolute number of cases is growing fastest in low- and middle-income countries. Approximately 60% of people with dementia live in LMICs, and this is expected to increase to 71% by 2050. By 2050, two-thirds of the global older adult population could reside in LMICs.

In South and Southeast Asia, a 2026 systematic review and meta-analysis estimated the overall prevalence of dementia at 3.0% (95% CI 2.0–5.0%), with Alzheimer's disease prevalence at 3.0% in LMICs compared with 2.0% in high-income countries. In India, prevalence among adults aged 60 and older ranges from 4.5% to 11% across states, influenced by education, lifestyle, and healthcare access.

The economic burden is immense. Dementia cost the global economy $1.3 trillion in 2019, with approximately 50% of costs attributable to informal care provided by family members and friends, averaging 5 hours per day. This unpaid care burden falls disproportionately on women and families in low-resource settings where formal care infrastructure is limited.

The 14 Modifiable Risk Factors

The 2024 Lancet Commission identified 14 modifiable risk factors across the life course. These factors account for up to 45% of dementia cases worldwide.

In early life, less education contributes approximately 5% of dementia cases. In midlife, the key risk factors include hearing loss, hypertension, obesity, excessive alcohol consumption, and traumatic brain injury. In later life, smoking, depression, social isolation, physical inactivity, diabetes, air pollution, untreated vision loss, and high LDL cholesterol contribute to risk.

Two factors were newly added in the 2024 update. High LDL cholesterol from around age 40 is associated with approximately 7% of dementia cases, and untreated vision loss in later life with approximately 2%. Air pollution is now officially recognized by WHO as a dementia risk factor.

The distribution and impact of these risk factors vary across populations. In Brazil, the population attributable fractions for less education (9.5% vs. 4.4%) and depression (6.3% vs. 3.0%) were higher than the global averages reported by the 2024 Lancet Commission. This variation underscores the need for context-specific prevention strategies.

A 2025 study published in The Lancet eBioMedicine expanded the risk factor model by incorporating four additional, often overlooked drivers: poverty, wealth shocks, income inequality, and HIV infection rates. The findings emphasized that current dementia prevention frameworks, largely based on high-income country data, miss key socioeconomic and gendered dimensions, particularly in low- and middle-income countries.

Evidence from Multidomain Intervention Trials

The most influential trial in dementia prevention is the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER). FINGER enrolled 1,260 participants aged 60–77 years who were at increased risk of dementia but had normal or slightly impaired cognition. Over two years, the intervention group received a multidomain programme combining nutritional guidance, physical exercise, cognitive training, social activities, and monitoring of cardiometabolic risk factors. The results showed significant benefits in executive function, processing speed, and overall cognitive scores compared with the control group.

A Cochrane systematic review of 9 randomized controlled trials involving 18,452 participants found a small but statistically significant positive effect of multidomain interventions on global cognition (Z-score mean difference 0.03, 95% CI 0.01–0.06). The effect was more pronounced in APOE ε4 carriers (mean difference 0.14) compared with non-carriers (0.04). However, the effect on dementia incidence remained uncertain (RR 0.94, 95% CI 0.76–1.18).

The Japan-Multimodal Intervention Trial for the Prevention of Dementia (J-MINT) tested a similar approach in 65–85 year olds with mild cognitive impairment, combining exercise, nutrition, cognitive training, and lifestyle disease management. Participants who actively attended exercise sessions showed the greatest likelihood of cognitive improvement. The trial also found that even individuals with genetic susceptibility to dementia appeared to maintain cognitive function through the multidomain programme.

Not all trials have shown positive results. The pre-DIVA trial in the Netherlands, which followed participants for a median of 10.3 years, found no significant difference in dementia incidence between intensive vascular care and standard care groups. The German AgeWell study and the French MAPT trial also showed limited or no cognitive benefits from multidomain interventions. These mixed results suggest that intervention timing, intensity, duration, and population characteristics matter.

The US SMARRT trial, which used personalized risk-reduction goals delivered by health coaches and nurses, showed improvement in composite cognitive scores of 0.14 standard deviations compared with standard health education. The MIND-China trial in rural Shandong province enrolled 5,765 participants aged 60–79 across 52 communities to test vascular risk factor management and multidomain interventions.

Implementation in Primary Care and Low-Resource Settings

Translating prevention evidence into practice requires feasible, scalable models. The WHO 2026 guidelines recommend tailored, multidomain interventions that typically focus on promoting healthy behaviours such as physical activity, cognitive stimulation, and dietary improvements, alongside management of cardiovascular and metabolic risk factors.

The Gerontological Society of America's KAER Toolkit for Brain Health provides a framework for primary care teams to initiate conversations about brain health, detect and diagnose dementia, and connect individuals with community-based supports. The framework consists of four steps: Kickstart, Assess, Evaluate, and Refer.

In India, the SMRUTHI-India trial is testing a multimodal care bundle approach for primary prevention of dementia in at-risk elderly populations. The study has developed a Care Bundle Module Booklet designed to implement strategic multimodal interventions that address salient modifiable factors including diabetes and protective factors such as dietary intervention.

A systematic review of targeted dementia risk reduction interventions in middle-aged adults in primary care concluded that given their substantive potential benefits and likely limited harms, these interventions may be considered for implementation in clinical practice after further evaluation.

A 2025 study published in Alzheimer's & Dementia examined dementia in a resource-constrained sub-Saharan African setting at the only neuropsychiatric facility in Northeastern Nigeria, highlighting the need for context-adapted prevention and management approaches in low-resource environments.

Cost-Effectiveness of Prevention

The economic case for dementia prevention is strong. An economic modelling study published in The Lancet Healthy Longevity in 2024 estimated that various population-level interventions to mitigate dementia risk factors in England are highly cost-effective. Low emission zones in cities to lower air pollution could save £260 million. Reductions to sugar content in food to address obesity could save £1.05 billion. Minimum unit pricing for alcohol could result in cost savings of £280 million and 4,767 quality-adjusted life years gained over an indefinite succession of age cohorts. Making bicycle helmets compulsory for children could reduce dementia risk from head injury, leading to £91 million in cost savings.

These findings demonstrate that population-level policies addressing environmental and behavioural risk factors can generate substantial economic returns. The DEVELOP research highlighted that many dementia risks require policy change to modify the environment rather than individual interventions or choices, underscoring the need for government action alongside clinical prevention.

Policy and National Dementia Plans

At the World Health Assembly in May 2025, Member States agreed to extend the Global Action Plan on the Public Health Response to Dementia to 2031. The original plan, unanimously adopted in 2017, has so far resulted in around 23% of countries developing national dementia plans.

Alzheimer's Disease International has emphasized the need for countries to prioritize dementia as a public health issue by integrating prevention, early diagnosis, and care into national health strategies. India, as a signatory to the Global Action Plan, has launched the National Programme for Health Care of the Elderly (NPHCE) and is implementing the District Mental Health Programme and National Tele Mental Health Programme. In June 2025, NITI Aayog announced plans to develop a national brain health blueprint aimed at improving quality of brain health and recognizing early signs of cognitive disorders and dementia.

Discussion

Key Findings

Three findings stand out.

First, the burden of dementia is large, growing, and shifting toward low- and middle-income countries. More than 57 million people live with dementia, and the number is projected to reach 139 million by 2050. More than 60% of cases are already in LMICs, and that proportion will rise. The economic cost exceeds $1.3 trillion annually, with half borne by unpaid family caregivers.

Second, a substantial proportion of dementia is preventable or delayable. The 2024 Lancet Commission identified 14 modifiable risk factors accounting for up to 45% of cases. The WHO 2026 guidelines provide updated recommendations covering 20 potentially modifiable risk factors in four categories. The evidence from the FINGER trial and other multidomain intervention studies demonstrates that structured lifestyle interventions can improve or maintain cognitive function in at-risk older adults.

Third, implementation is feasible but requires system-level commitment. Primary care frameworks like the KAER Toolkit provide practical pathways for integrating brain health into routine clinical practice. Population-level policies addressing air pollution, cardiovascular risk factors, and health behaviours have demonstrated cost-effectiveness. India's SMRUTHI-India trial and NITI Aayog's brain health blueprint represent emerging efforts to translate prevention evidence into national action.

Comparison with Prior Literature

These findings align with and extend previous analyses. The 2024 Lancet Commission updated the evidence base from earlier reports by adding high LDL cholesterol and untreated vision loss as risk factors, raising the proportion of preventable dementia from approximately 40% to 45%. The WHO 2026 guidelines reflect a life-course approach, recognizing that risk factors accumulate over time and may have different impacts at different life stages.

The FINGER trial's findings have been replicated and extended in other settings, including the J-MIND trial in Japan and the MIND-China trial in rural China. However, the mixed results from pre-DIVA, AgeWell, and MAPT trials suggest that the effectiveness of multidomain interventions depends on factors that are not yet fully understood, including intervention timing, duration, and population characteristics.

The cost-effectiveness evidence from England provides a strong economic rationale for population-level prevention policies. This aligns with the 2025 Lancet eBioMedicine study emphasizing that socioeconomic and gendered dimensions of dementia risk, particularly poverty and income inequality, are often overlooked in prevention frameworks.

Limitations

This synthesis has limitations. It is not a systematic review. The literature selection was purposive and may have omitted relevant studies. The evidence on multidomain interventions does not conclusively establish their effect on dementia incidence, only on cognitive outcomes. The FINGER trial and other major studies were conducted primarily in high-income settings, and their applicability to low-resource settings remains uncertain. The cost-effectiveness evidence is drawn largely from England, and economic returns may differ in other contexts. National dementia plan data are incomplete, and implementation varies widely across countries. Finally, the dementia prevention field is evolving rapidly, and new evidence may change the recommendations over time.

Public Health Implications

The implications for policy and practice are substantial.

First, dementia prevention must be integrated into primary care. The WHO 2026 guidelines and the KAER Toolkit provide practical frameworks for screening, assessment, and intervention in primary care settings. Primary care providers should be trained to discuss brain health, identify modifiable risk factors, and offer evidence-based interventions. This requires investment in training, tools, and referral pathways.

Second, population-level policies are essential. Individual behaviour change alone will not reduce dementia risk at scale. Air pollution control, tobacco and alcohol regulation, healthy food policies, and safe built environments are critical components of a comprehensive prevention strategy. The cost-effectiveness evidence supports these investments.

Third, equity must be central. Dementia risk is shaped by education, income, and access to healthcare. Prevention strategies must reach the most vulnerable populations, including those in low-income countries and marginalized communities. The expansion of risk factor frameworks to include poverty and income inequality represents an important step toward more equitable prevention.

Fourth, national dementia plans must be developed and implemented. Only about 23% of countries have national dementia plans. The extension of the WHO Global Action Plan to 2031 provides an opportunity for countries to prioritize dementia prevention, diagnosis, and care. India's NITI Aayog brain health blueprint is a promising step, but it must be matched by funding, implementation, and accountability.

Fifth, research must expand to low- and middle-income settings. The majority of dementia research, including prevention trials, has been conducted in high-income countries. The strategies that work in Finland may not work in Nigeria or India. Context-adapted research is urgently needed.

Conclusion

Dementia is the seventh leading cause of death globally. It affects more than 57 million people. It costs $1.3 trillion annually. And it is growing.

But it is not inevitable. The 2024 Lancet Commission identified 14 modifiable risk factors that account for up to 45% of dementia cases. The WHO 2026 guidelines provide evidence-based recommendations for reducing risk across the life course. The FINGER trial and other multidomain intervention studies demonstrate that structured lifestyle interventions can improve cognitive function in at-risk older adults. Cost-effectiveness analyses show that population-level policies can generate substantial economic returns.

The evidence is there. The tools are available. What is needed is action.

Health leaders must integrate dementia prevention into primary care. Policymakers must implement population-level interventions addressing air pollution, cardiovascular risk factors, and health behaviours. Governments must develop and fund national dementia plans. Researchers must expand prevention research to low- and middle-income countries. And communities must be engaged as partners in brain health promotion.

The WHO Director-General put it simply: "Countries now have clear, evidence-based recommendations they can put into practice immediately to protect people's cognitive health".

The window for meaningful intervention is open. It will not stay open indefinitely. The time to act is now.

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