It is estimated that millions of people around the world have dementia. The number keeps increasing when the global population gets aged.
Finding out possible risk factors for dementia that can be modified plays an important role in preventing and managing this health issue.
A recent study published in the BMJ journal indicates that being exposed to traffic noise may increase the risk of dementia.
In the research, scientists included around 2 million people in Denmark, aged at least 60 years old. All of them lived in Denmark between 2004 and 2017. The authors measured their exposure to railway noise and road traffic.
During this period, they used the national health registers of Denmark to find out cases of dementia, including Parkinson’s disease, vascular dementia, and Alzheimer’s disease.
More than 103,000 dementia cases were reported during this period. After analyzing the data, scientists found out a link between traffic noise and increased risk of dementia, particularly Alzheimer’s disease.
Some animal studies suggest that being exposed to noise continually may trigger the production of key genes, which result in the neuropathological adjustments associated with Alzheimer’s disease.
Traffic noise is the second-worst environmental risk factor for general public health in Europe, only after air pollution. At least 1 out of 5 people in the continent is exposed to traffic noise above 55 decibels, which is the recommended safe level.
Traffic noise at night is particularly concerning because sleep is very important for cognitive and mental restoration.
Many experimental studies indicate that fragmented sleep due to noise disturbance may increase the risk of systemic inflammation, changes in the immune system, and increased oxidative stress. All of these are major risk factors for the development of Alzheimer’s disease and dementia.
In addition, the scientists note a decline in the risk at the most exposed parts of buildings. This contradiction may be explained by better insulation of sounds at higher levels of noise.
While this was a comprehensive and large study, it was still observational. This means we could not establish causality.
Another drawback is the lack of data about the lifestyle habits of participants, which may affect the risk of developing dementia. Also, the team did not consider noise from other sources, such as work sites, industrial activities, and airports.
Further research should be done to help us learn more about the harmful effects of noise pollution on public health.