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Proximity to Busy Roads Increases Dementia Risk

A recent study of 6.6 million people showed a connection

By Shayla Thiel Stern

Those of us who live near a busy street or highway know that the rumbling of noisy motors, screaming of sirens and blaring horns can be disruptive to sleep. And fumes from engine exhaust and construction might move us to close the windows even on a sunny day. But now we have another concern to consider: New research has linked living near a busy road to an increased risk of dementia.

A study from scientists at Public Health Ontario tracked 6.6 million people and learned that one in 10 cases of dementia or Alzheimer’s is a person who lived by a street with heavy traffic.

The Relationship of of Pollution and Noise to Dementia

Previous research has illuminated the link between traffic noise and air pollution to a reduction of the brain’s connective tissue and lower cognition, notes a story in The Guardian about the dementia study’s findings. The Guardian also reported on a 2016 study that found toxic air pollution particles discovered in “abundant” quantities on human brains — also suggesting a causal relationship to Alzheimer’s and dementia. In 2012, researchers at Johns Hopkins University School of Medicine in Baltimore in conjunction with the National Institute on Aging, found that older adults with hearing loss were more likely to develop cognitive decline over time than those who retain their hearing, suggesting that daily exposure to loud noise could affect brain health.

The risk is statistically small but significant, according to the study, which was published in The Lancet, as a result of 11 years of data that also tracked incidences of Parkinson’s disease and multiple sclerosis. Only the connection between heavy traffic and dementia was found, though. The study participants who lived in a major city within 50 meters (.03 miles) of a major road and who lived in the same house or apartment for the duration of the study had the highest risk of dementia: 12 percent.

Busy Street Living Becomes More Common

As the global population increases and urban centers grow ever larger, this link could add to an already growing public health crisis around living space.

“Increasing population growth and urbanization has placed many people close to heavy traffic, and with widespread exposure to traffic and growing rates of dementia, even a modest effect from near-road exposure could pose a large public health burden," Hong Chen, the research scientist who led the Public Health Ontario study, told The Guardian.

The Canadian research team took potentially confounding factors like socio-economic status, education and health conditions (diabetes, for example) into their calculations.



However, Ray Copes — a co-author of the study and the chief of environmental and occupational health at Public Health Ontario — told the Guardian that if you live in an urban area, you can decrease your chance of dementia by limiting urban street noise and pollution when you are out of the house. He suggested using side streets for walking, running in parks and biking on quieter roads.

The longer-term solutions may come from urban planners and architects, he said, urging them to consider air and noise pollution when planning urban spaces.

“The real implications are not for individual choice, but at the societal and policy level,” Copes said.



Shayla Thiel Sternis the former Director of Editorial and Content for Next Avenue at Twin Cities PBS. Read More
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