“Noise does not do good, good does not make noise”, said Frenchman Vincent de Paul. Living in big cities and working in noisy offices or factories, we forget the sound of silence as we immerse ourselves more and more in the noise, which becomes the soundtrack of our life. However, our brain needs silence. Science is warning that noise can take a heavy toll on us.
Noise, the modern plague that affects our brain
American researchers have called the noise the “modern plague.” They indicate that “Environmental noise pollution, a form of air pollution, is a threat to health and well-being. It is more severe and widespread than ever before, and it will continue to increase in magnitude and severity because of population growth, urbanization, and the associated growth in the use of increasingly powerful, varied, and highly mobile sources of noise. It will also continue to grow because of sustained growth in highway, rail, and air traffic, which remain major sources of environmental noise”.
They further note that “The potential health effects of noise pollution are numerous, pervasive, persistent, and medically and socially significant.” They conclude that “Noise produces direct and cumulative adverse effects that impair health and that degrade residential, social, working, and learning environments with corresponding real (economic) and intangible (well-being) losses.”
Now, researchers at the University of Michigan have gone a step further by verifying that the noise we are exposed to throughout life could trigger dementia in old age. They analyzed 5,227 people over 65 years of age, who were given cognitive evaluations every three years, in addition to checking the level of noise they were subjected to in their neighborhood.
They found that an increase of just 10 decibels in ambient noise corresponded to a 29-36% increase in the probability of developing cognitive impairment. “These results join emerging evidence suggesting that noise may influence late‐life cognition and risk of dementia”, they concluded.
It is worth clarifying that “A harmful level of noise can be the exposure to more than 85 decibels (dB) for eight hours or 100 dB for 15 minutes”, according to the WHO. To put noise in perspective, it is enough to know that in a traffic jam we are exposed to an average of 90 dB while a drill or a horn generates 120 dB.
The neurotoxicity of noise
Previous research had already warned of the dangers of noise for our brain. A study carried out at Cornell University revealed that the constant sound of airplanes can cause an increase in blood pressure and the level of stress in children living in areas under airport flight routes, in addition to causing a deficit in language acquisition.
In 1975, researchers from New York University analyzed children attending a school located near an elevated railroad. Half of the students who participated in the research were in classrooms facing the railroad and the other half were in classrooms in the quieter back part of the school. Students on the quieter side were found to perform better on reading tests and by sixth grade were one point ahead of students who attended the loudest classrooms.
Noise neurotoxicity could also affect adults, precipitating cognitive decline and dementia due to the effects of inflammatory processes. In experiments with animals it has been found that noise causes neuropathological changes indicative of dementia. In mice, for example, the exposure to noise promotes the production of beta amyloid in hippocampal tissue, which is precisely the origin of dementias.
Oxidative stress processes, inflammation, degenerative changes in synapses and less frequency of neuronal activation have also been observed. In addition, animals exposed to noise show a decrease in their learning and memory capacity.
Beyond the neuropathological consequences, scientists believe that the vascular effects of noise can also trigger dementia processes as they have been linked to an increased heart rate, peripheral vasoconstriction and increased risk of hypertension. All risk factors for dementias.
However, the main problem is that noise prevents our brain from resting, keeping it constantly on alert, profoundly affecting the quality of sleep.
In fact, if we are continuously exposed to noise, our brain is constantly busy, processing incoming information. Our mind is exposed to a continuous flow of external stimuli that takes away the essential rest.
When we cannot sleep well, because the sleep is not restful and we suffer continuous awakenings throughout the night, our brain will not be able to get rid of the waste substances of its metabolism. That is why sleep problems have been linked to the appearance of different types of dementia.
Enjoy the silence
Silence is a necessity of the mind, although in the modern world it has become a luxury. Therefore, the first step to living in a quieter environment is to ensure that we do not contribute to noise pollution. The second step is to look for bubbles of silence that allow us to access a calmer environment where we leave behind irritability, frustration, stress or confusion.
We can leave the city to enjoy the silence surrounded by nature, which also implies turning off the mobile. It is about learning to be, without speaking, letting that healing silence reach every fiber of our body, so that our brain can regenérate itself.
Weuve, J. et. Al. (2020) Long‐term community noise exposure in relation to dementia, cognition, and cognitive decline in older adults. Alzheimer & Dementia; DOI: 10.1002/alz.12191.
Cui, B. et. Al. (2015) Chronic Noise Exposure Acts Cumulatively to Exacerbate Alzheimer’s Disease-Like Amyloid-β Pathology and Neuroinflammation in the Rat Hippocampus. Nature Scientific Reports; 5: 12943.
Basner, M. et Al. (2014) Auditory and non‐auditory effects of noise on health; Lancet; 383(9925): 1325-1332 .
Evans, G. W. & Maxwell, L. (1997) Chronic Noise Exposure and Reading Deficits: The Mediating Effects of Language Acquisition. Environment and Behavior; 29(5), 638–656.
Bronzaft, A. L. & McCarthy, D. P. (1975) The Effect of Elevated Train Noise On Reading Ability. Environment and Behavior; 7(4): 517-528.