Noise from road traffic and railways to be associated with an increased risk of all-cause dementia, scientists say.
The roaring noise of heavy traffic can grate on your nerves, but long-term exposure to it can do worse than that: it can increase the risk of dementia, obesity, diabetes and heart disease.
This seemingly unlikely cause-and-effect relationship between traffic noise and a variety of adverse health conditions was discovered by scientists in Denmark who examined the links between prolonged explosure to transport noise and an increased risk of dementia among nearly 2 million adults over the age of 60 in a study that took more than a decade to complete, from 2004 to 2017.
The Danish researchers’ findings indicate that there is a marked link between transport noise and an increased risk of adverse mental health conditions. For example, in 2017 more than 1,200 cases of dementia out of a total of almosy 8,500 in the Scandinavian nation could be attributed to transport noise, including noise produced by vehicles and trains.
“In this large nationwide cohort study, we found transportation noise from road traffic and railways to be associated with an increased risk of all-cause dementia and dementia subtypes, especially Alzheimer’s disease,” the researchers write. “These associations showed a general pattern of higher hazard ratios with higher noise exposure, but with a levelling off or even small declines in risk at higher noise levels.”
This linkage is disconcerting as dementia is an increasingly common health condition in the ageing populations of developed nations. Growing urbanization worldwide also means that more and more people are living in areas where they are exposed to loud traffic noise all day long.
The reasons for how traffic noise adversely influences our health will need to be further investigated, but likely explanations include disturbances to sleep and the release of stress hormones, which can result in chronic inflammation, lower immune system responses and coronary heart disease.
However, they caution, lifestyle habits such as lack of exercise and unhealthy diets are well-established contributing factors in the onset of dementia and other adverse health conditions.
“Expanding our knowledge of the harmful effects of noise on health is essential for setting priorities and implementing effective policies and public health strategies focused on the prevention and control of diseases, including dementia,” the researchers write.
Conversely, by mitigating traffic noise and air pollution through various policies, we can ensure that many more people can lead healthier lives, the researchers note. Insulating homes against traffic noise could be one such solution. Another could entail barring heavy traffic from heavily populated areas of cities during certain periods.
“Reducing noise through transportation and land use programs or building codes should become a public health priority,” stresses a team of researchers who commented on the findings.