According to a new Danish study, prolonged exposure to noise from road or rail traffic is associated with a higher risk of developing dementia, including Alzheimer’s disease.
- The researchers studied in 2 million Danes the association between long-term residential exposure to road and rail traffic noise and the risk of dementia for an average of 8.5 years.
- They found that daily exposure to loud road noise increased the risk of developing Alzheimer’s disease by up to 27%. This risk is also 24% greater with exposure to train noise.
The incessant buzzing of road traffic, the noise of trains passing not far from homes or the roar of planes landing and taking off… When repeated on a daily basis, these noise nuisances can have clear consequences on the quality of life, but also on health. Several studies have previously demonstrated this, showing their detrimental impact on hearing and cardiovascular health, and their correlation with the risk of obesity and diabetes.
But until now, there has been little reliable scientific data on the link between transport noise and the risk of dementia. This is now done with this new study published in the British Medical Journal. According to its authors, no less than 1,216 of the 8,475 cases of dementia recorded in Denmark in 2017 could be attributed to noise pollution caused by cars and trains.
Up to 27% higher risk of Alzheimer’s
To reach this conclusion, the researchers studied the association between long-term residential exposure to road and rail traffic noise and the risk of dementia in two million adults over the age of 60 living in Denmark between 2004 and 2017.
For this, they used data from national health registries where cases of dementia (Alzheimer’s disease, vascular dementia and dementia related to Parkinson’s disease) are identified over an average of 8.5 years. A total of 103,500 new cases of dementia were recorded during the study period.
After controlling for other factors, the researchers found that a 10-year average exposure to road traffic and railway noise was associated with a higher risk of dementia from all causes.
In more detail, noise pollution from cars and trains is associated with an up to 27% higher risk for Alzheimer’s disease when exposure to road traffic noise is greater than 55 dB. The risk of Alzheimer’s is up to 24% higher for an exposure to railway noise of 50 dB compared to an exposure of less than 40 dB.
In contrast, only road traffic noise was associated with an increased risk of vascular dementia, not railway noise.
How noise disrupts health
Although an observational study, the authors suggest that this noise exposure releases stress hormones and disrupts sleep, which can lead to coronary heart disease, changes in the immune system and inflammation. . However, all of these elements are considered to be early events in the onset of dementia and Alzheimer’s disease.
“If these results are confirmed in future studies, they could have an important effect on the estimation of disease burden and health costs attributed to transport noise. It is essential to expand our knowledge of the harmful effects of noise on health to establish priorities and implement effective public health policies and strategies focused on the prevention and control of diseases, including dementia”conclude the researchers.
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