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• For primary prevention, an approach addressing not only individual effort but also Social Determinants of Health (SDH), such as the neighborhood environment, is essential. Improving environmental factors through urban planning can be an effective strategy for health promotion.
• Living environments are directly linked to lifestyle habits such as physical activity and social interaction. Interventions in the physical environment, such as the creation and improvement of walkable sidewalks and parks, have the potential to raise the standard of health for residents.
• Moving forward, the perspective of creating cities where people become healthy naturally just by living there “Healthy by Default” is crucial. Through this, we aim for urban planning in which everyone can maintain their health without difficulty.

 

Introduction: Neighborhood Environment and Health

Our health is not determined solely by biological factors such as medical care and genetics. It is now an internationally established finding that Socio-Economic Status (SES), such as income and education, is a major factor influencing our health (Marmot et al., 2008). These factors are known as Social Determinants of Health (SDH), and their importance is being reaffirmed globally.

In recent years, in addition to SES, the perspective that “the type of city one lives in”, that is, the neighborhood environment itself, is a factor linked to people’s health behaviors and the risk of dementia onset has become widespread. Indeed, systematic reviews and meta-analyses, which are highly reliable scientific research methods that synthesize global research results, have increasingly clarified this association (Barnett et al., 2017; Kuiper et al., 2015). These findings are attracting attention primarily from the perspective of “disease prevention,” particularly regarding dementia.

However, “prevention” here refers not only to primary prevention, which refers to preventing the onset of disease from a healthy stage through the improvement of lifestyle habits and the promotion of social connections, but also includes a broader concept in health policy that encompasses secondary prevention (early detection and diagnosis) and tertiary prevention (prevention of aggravation). This column focuses specifically on primary prevention of dementia, highlighting the creation of supportive environments where primary prevention is realized naturally through the local environment.

Does Urban Environment Influence Dementia Risk?

Daily behaviors (such as physical inactivity and social isolation) have been identified as modifiable risk factors that increase the prevalence of dementia (Livingston et al., 2024). Can these risks be reduced through urban design and neighborhood environments? We will examine the evidence answering this question.

For example, research in Japan has reported that “a scarcity of grocery stores in the neighborhood increases the risk of dementia”, suggesting that shopping supports opportunities for going out and walking time for older adults (Tani et al., 2019). Additionally, longitudinal studies have reported that participation in community salon activities, such as calligraphy, origami, and intergenerational exchange, above a certain frequency is associated with the reduction of cognitive decline. Some studies suggest the possibility of preventing dementia onset by establishing interactive salons within the local community (Hikichi et al., 2017).

Of course, these studies do not prove a complete causal relationship. However, many studies suggest a positive association where neighborhood physical environments, such as fresh food stores and parks, and social environments, such as community connections and opportunities for social participation, influence health through behavior. This offers a novel perspective: by involving policy in the “design of daily life”, an area unreachable by individual effort or medical intervention alone, behaviors such as going out, interacting, and exercising accumulate naturally. As a result, brain health is maintained, thereby leading to well-being.

Healthy-by-Default Cities

This column has focused on evidence for primary prevention to reduce the risk of dementia onset. However, we wish to emphasize here that “cities conductive to prevention are also livable cities for people living with dementia.”

To achieve both goals, the concept of “Primordial Prevention” is important. This approach does not rely solely on individual will or effort but establishes an environment that enables people to engage in healthy behaviors naturally, without conscious effort. For example, environments such as barrier-free, walkable sidewalks and attractive parks or libraries where anyone can casually drop by play a role in promoting outings for older adults and reducing dementia risk. Simultaneously, these environments remove barriers for people living with dementia when going out, thereby serving as a foundation for “coexistence” that supports social participation.

On the other hand, from the perspective of public health ethics, we must also touch upon “individual freedom versus intervention”. Regarding the approach of “making people healthy naturally,” concerns may arise that the government is seeking to control individual behavior (paternalism). In reality, the goal here is not control, but to “offer choices”. For instance, if there is a bench in the shade, one might think, “I’ll rest a bit,” and if there is a walkable promenade, one might think, “I’ll take a walk.” These are instances where the environment invites behavior; of course, the freedom to pass by if uninterested, or to take an entirely different action, is guaranteed. Based on this way of thinking, shaping the local environment is a matter of setting the stage for those who wish to be healthy to act on that desire. Whether to step onto that stage or remain in the audience should be decided freely, depending on an individual’s mood and physical condition. This is not “coercion,” but rather the gentle placement of attractive options that people may choose to engage with. This represents an ideal and ethically appropriate form of health-oriented urban planning.

Furthermore, investing in the local environment helps create a city where everyone can live with ease, thus reducing the risk of dementia and providing reassurance for those who may go on to develop it. Supporting this perspective, sociologist Eric Klinenberg argues that “social infrastructure” such as parks and libraries operated by municipalities provides points of contact with the outside world that make people “want to go out,” which is effective in preventing social isolation (Klinenberg, 2018). Seeing as there are attractive places where people can commune, people naturally go out and converse with others. This approach, facilitating how environments shape behavior, is the essence of urban planning grounded in the Social Determinants of Health (SDH). Rather than pursuing health out of anxiety or fear about the future, engaging in everyday activities because the city itself is inviting helps protect brain and mental health, as well as overall well-being. This is arguably the ideal form of a “healthy-by-default” city.

Future Prospects: Urban Planning Friendly to All

Moving forward, when formulating municipal dementia policies through ordinances and other means, it is crucial to incorporate a Social Determinants of Health (SDH) perspective into policy design. Creating roads that people want to walk on and places where people want to gather promotes health among the working-age population, supports dementia prevention for older adults, and enables social participation for people living with dementia. A key challenge ahead will be to advance evidence-based, citizen-centered policies that address “prevention” and “coexistence” not as separate goals, but as a unified approach to health-oriented urban planning, and to rigorously evaluate their effectiveness.

Conclusion

The perspective of preventing dementia from the “city” level involves not only medical policy but also cuts across urban policy and welfare policy. In the coming era, the idea that “the city supports health” will be vital. Promoting real-world evidence driven policies that approach health and well-being from the perspective of SDH, our institute will continue to deepen its knowledge and disseminate findings that contribute to broad health promotion, including dementia.

 

References

• Barnett, D. W., Barnett, A., Nathan, A., Van Cauwenberg, J., Cerin, E., & Council on Environment and Physical Activity (CEPA) – Older Adults working group. (2017). Built environmental correlates of older adults’ total physical activity and walking: A systematic review and meta-analysis. International Journal of Behavioral Nutrition and Physical Activity, 14(1), 103. https://doi.org/10.1186/s12966-017-0558-z
• Hikichi, H., Kondo, K., Takeda, T., & Kawachi, I. (2017). Social interaction and cognitive decline: Results of a 7-year community intervention. Alzheimer’s & Dementia: Translational Research & Clinical Interventions, 3(1), 23–32. https://doi.org/10.1016/j.trci.2016.11.003
• Klinenberg, E. (2018). Palaces for the People: How Social Infrastructure Can Help Fight Inequality, Polarization, and the Decline of Civic Life. Crown.
• Kuiper, J. S., Zuidersma, M., Oude Voshaar, R. C., Zuidema, S. U., van den Heuvel, E. R., Stolk, R. P., & Smidt, N. (2015). Social relationships and risk of dementia: A systematic review and meta-analysis of longitudinal cohort studies. Ageing Research Reviews, 22, 39–57. https://doi.org/10.1016/j.arr.2015.04.006
• Livingston, G., Huntley, J., Sommerlad, A., Ames, D., Ballard, C., Banerjee, S., … Mukadam, N. (2024). Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. The Lancet, 404(10452), 572–628. https://doi.org/10.1016/S0140-6736(24)01296-0
• Marmot, M., Friel, S., Bell, R., Houweling, T. A., Taylor, S., & Commission on Social Determinants of Health (2008). Closing the gap in a generation: health equity through action on the social determinants of health. The Lancet, 372(9650), 1661–1669. https://doi.org/10.1016/S0140-6736(08)61690-6
• Tani, Y., Suzuki, N., Fujiwara, T., Hanazato, M., & Kondo, K. (2019). Neighborhood food environment and dementia incidence: The Japan Gerontological Evaluation Study cohort survey. American Journal of Preventive Medicine, 56(3), 383–392. https://doi.org/10.1016/j.amepre.2018.10.028

 

Column author

Takeru Kobayashi (Intern, Health and Global Policy Institute)