A massive study spanning two million Danes concluded that exposure to noise results in stress, fatigue, poor sleep and, in turn, even more stress, which ultimately increases the chances of developing dementia.
For the first time ever, a link between loud traffic noise and an increased risk of dementia has been documented
Researchers processed data from millions of Danes from 2004 to 2017 to establish a 27 percent higher risk of getting Alzheimer’s and an 18 percent higher chance of developing dementia when subjected to over 55 decibels of traffic noise over long periods of time.
In the massive research project, undertaken by the University of Southern Denmark (SDU) in collaboration with Roskilde University, Odense University Hospital (OUH) and the University of Copenhagen, the addresses of two million Danes and their proximity to busy roads and rail lines were taken into account.
The data was subsequently cross-checked with national health registries to identify instances of dementia (including Alzheimer’s disease, vascular dementia and Parkinson’s). Finally, the report concluded that of the 8,475 cases of dementia registered in 2017, 1,216 can be linked to traffic noise.
The effect of noise on health has been linked with the release of stress hormones and sleep disturbance, which leads to coronary artery disease, changes in the immune system and infection – all early indicators of early onset dementia.
“The results are surprising since it’s the first time we have established a clear connection between traffic noise and the development of dementia” Manuella Lech Cantuaria, an assistant professor at the Clinical Institute at the University of Southern Denmark and the head of research, said in a statement.
She expressed hope that the results can bolster further research and efforts to improve public health.
“We want to increase the focus on the health risks associated with being exposed to noise, which is not only an annoyance but also harmful to your health. Hopefully, our results can help influence urban development,” Cantuaria said.
According to her, the results should be considered in noise regulation programs, including highway shielding and noise-reducing asphalt.
“We show a connection between noise and dementia, where the hypothesis is that it is the noise that stresses the body and triggers poor sleep. It creates fatigue, which in turn triggers more stress and increases the risk of developing dementia. And the higher the noise, the more the risk increases,” associate professor at SDU Jesper Hvass Schmidt explained.
An earlier study by the University of Copenhagen, which has tracked nearly 5,000 people over a 50-year stretch found a “convincing” link between dementia and hard, physically demanding labour, as opposed to office work and other sedentary occupations.