People who live near busy roads or railways are more likely to develop dementia — that is, a decline in mental faculties severe enough to interfere with daily life. This is the warning issued by a group of scientists who have found a correlation between the noise produced by means of transport and an alteration of cognitive functions that translates, in the majority of cases, into Alzheimer's disease.

The results of the study conducted in Denmark

This is the most in-depth study ever carried out in this field: it involved two million Danes aged over sixty, whose health conditions were monitored from 2004 to 2017. The results were published in the British medical journal (Bmj), a prestigious medical journal. The researchers concluded that 1,216 of the 8,475 cases of dementia recorded in Denmark in 2017 are attributable to noise pollution linked to everyday road traffic. Of these, 963 are traceable to road transport, and 253 to rail transport.

The risk grows as exposure to noise increases. The latter is thought to affect health for various reasons — for example, because it causes sleep disturbances and the release of "stress hormones", factors that can give rise to cardiovascular disease, alterations of the immune system and inflammation — all triggers of dementia. It was previously discovered that traffic noise can also cause obesity and diabetes.

The number of people affected by dementia is growing

Dementia is one of the greatest global health challenges. The number of people suffering from it is estimated to exceed 130 million by 2050. Beyond the importance of staying mentally and physically active and following a healthy diet, specialists believe that environmental factors also play a role in the development of symptoms.

"If these findings are further confirmed by future research, they could have a significant impact on our awareness of these conditions and of the healthcare costs attributable to noise pollution," the experts write. "Deepening our knowledge of the negative effects of noise on health is essential in order to implement health policies aimed at the prevention and control of dementia."

The new study carried out in Denmark confirms that noise pollution — just like air pollution — is a threat not only to the environment, but also to public health. Committing to reducing both should become a priority from every point of view.