Living near major roads increases dementia risk

Dementia is a growing health risk, affecting millions of people and their families. As life expectancy increases, so does the number of dementia cases, making prevention more important than ever.

While genetics and lifestyle choices play a role, researchers are now looking beyond personal factors. The environment we live in can either increase the risk of dementia or help protect brain health.

A recent study from the University of Georgia College of Public Health sheds light on the impact of surroundings on dementia risk.

The research team, led by Professor Suhang Song, set out to investigate how the environment affects brain health. The results show that avoiding pollution and spending more time in green spaces may lower the risk of dementia.

“These numbers show that living in a dementia-friendly environment is important to delay or prevent cognitive decline and the onset of dementia,” said Professor Song.

How environment affects dementia risk

The researchers studied 54 reports on how the environment affects brain health. They closely analyzed 21 of them to measure the impact more accurately.

They found that air pollution and traffic noise increase dementia risk, while green spaces and walkability help prevent cognitive decline.

By focusing on objectively measured environmental factors rather than self-reported data, the study provides stronger evidence than previous research.

Air pollution and dementia risk

Living near major roads increases dementia risk by about 10%. Exposure to fine particulate matter (PMx) raises risk by 9%, and nitrous oxide (NOx) exposure adds another 10%. Noise pollution has also been linked to a 9% increase in risk.

Long-term exposure to traffic pollution is particularly harmful. Tiny air pollution particles called PM2.5 are linked to memory loss and slower thinking. However, the impact is not the same everywhere. In some places, studies found no strong link.

One possible reason is that people in those areas change their behavior – like staying indoors when pollution levels are high – so they are exposed to less pollution, which may reduce its harmful effects on the brain.

Protective role of green spaces

Access to parks, forests, and water bodies lowers dementia risk by about 6%. These environments promote physical activity, reduce stress, and improve air quality.

Walkable neighborhoods with easy access to food stores, community centers, and healthcare also support cognitive health.

“Based on these findings, we can suggest that people visit parks or forests more often and also live further from the major roads,” said Professor Song. “Also, living in a community where there is more walkability, or being close to local amenities like bookstores, health care centers and more is helpful.”

Cities designed with cognitive health in mind should prioritize pedestrian-friendly streets, connected pathways, and accessible public spaces.

Encouraging mixed-use developments, where homes, shops, and essential services are within walking distance, can help create healthier environments for aging populations.

Rethinking urban planning

This study emphasizes the need for urban designs that reduce pollution and increase green space. Cities should prioritize public parks, pedestrian-friendly streets, and better air quality to lower dementia risk.

“The biggest advantage of this paper is to quantify the association between certain factors and cognitive health. This analysis can provide evidence for data-driven urban planning and support decision makers,” said Professor Song.

Future research on dementia risk

One of the strengths of this study was its focus on objective data. Many past studies relied on subjective reports, which can introduce bias. This research used measurable environmental factors, making the conclusions more reliable.

Future studies should continue using objective methods to investigate the link between surroundings and dementia risk. Understanding the long-term effects of urban design, pollution exposure, and community layouts can help shape policies that improve cognitive health outcomes.

Professor Song hopes this study encourages more research on how the environment affects brain health. Using data-driven solutions, experts can help build communities that reduce dementia risk and support well-being.

A better understanding of these factors could lead to smarter urban planning and healthier living spaces for future generations.

The study is published in the journal Ageing Research Reviews.

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