Exposure to noise from road traffic and railways is associated with an increased risk of dementia, according to a new study.
Research has consistently linked transport noise to health conditions including heart disease, diabetes and obesity, but studies on transport noise and dementia were scarce and small, and findings inconsistent, reports the Guardian.
Now the new study, the largest of its kind, involving two million adults, conducted over more than a decade, has concluded that people living in areas with transport noise face a higher risk of dementia, especially Alzheimer’s disease. The findings were published in the BMJ.
Researchers investigated the association between long-term residential exposure to road traffic and railway noise and the risk of dementia among two million adults aged over 60 and living in Denmark between 2004 and 2017. The level of exposure at the most- and least-exposed sides of buildings was estimated for every residential address in the country.
After taking account of potentially influential factors related to residents and their neighbourhoods, the study concluded that as many as 1,216 out of the 8,475 cases of dementia registered in Denmark in 2017 could be attributed to transport noise.
Of those, “the diagnosis in an estimated 963 patients was attributed to road traffic noise, and in 253 patients to railway noise”.
Previous research has linked air pollution to dementia risk, but in this study, researchers found a separate connection between transport noise and dementia.
The findings suggested it may be possible to slash the burden of dementia by tackling traffic noise, the researchers said. “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,” they said.
Possible explanations for why noise may affect health include the release of stress hormones and sleep disturbance, which lead to heart disease, changes in the immune system and inflammation – all of which are seen as being linked to the onset of dementia.