Prolonged exposure to traffic noise is associated with a raised risk of developing dementia, according to Danish research published today.
Transportation noise is considered the second worst environmental risk factor for public health in Europe after air pollution, with about one-fifth of people in Europe being exposed to transportation noise above the recommended level of 55 decibels.
Although studies have consistently linked transportation noise to various diseases and health conditions, such as coronary heart disease, obesity and diabetes, little research has been undertaken on transportation noise and dementia.
Researchers investigated the association between long-term residential exposure to road traffic and railway noise and risk of dementia among two million adults aged over 60 and living in Denmark between 2004 and 2017.
Noise from road traffic and railway was estimated at the most and least exposed sides of all residential addresses in Denmark and the team analysed national health registers to identify cases of all-cause dementia and different types of dementia – Alzheimer’s disease, vascular dementia, and Parkinson’s disease related dementia – over an average of 8.5 years.
Writing in the latest edition of The BMJ, they say they found 103,500 new cases of dementia during the study period and after taking account of potentially influential factors found that a 10-year average exposure to road traffic and railway noise at the most and least exposed sides of buildings was associated with a higher risk of all-cause dementia.
Further analysis showed both road traffic and railway noise were associated with a higher risk of Alzheimer’s disease, which they said was up to up to 27% higher for exposure to road traffic noise of 55 dB and up to 24% higher for exposure to railway noise of 50 dB compared with less than 40 dB.
Only road traffic noise was associated with an increased risk of vascular dementia.
Although this is an observational study, they say possible explanations include release of stress hormones and sleep disturbance, leading to a type of coronary artery disease, changes in the immune system.
“If these findings are confirmed in future studies, they might have a large effect on the estimation of the burden of disease and healthcare costs attributed to transportation noise,” they say.
“Expanding our knowledge on 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.”
Cantuaria ML, Waldorff FB, Wermuth L et al. Residential exposure to transportation noise in Denmark and incidence of dementia: national cohort study. BMJ 9 September 2021
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