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We know that preventing cognitive decline is infinitely easier than reversing it. Engaging in many lifestyle choices that promote good long-term brain health, “brain hygiene” is the most effective defense against dementia and dementia subtypes. 

Make it a routine to get enough high-quality deep sleep, maintain a heart-healthy diet, and manage stress and anxiety through exercising and reading. Practicing moderation when it comes to alcohol also promotes a clean, healthy brain.

It sounds simple, but we know that dementia is a range of conditions brought on by damaged brain cells. Anything you can do to keep your brain cells intact may help keep these conditions at bay.

Alzheimer’s, for instance, is typically caused by either a buildup of excess proteins or “plaque” interfering with communication between neurons or a blockage of blood vessels in the brain that has a similar effect. 

This accumulation of proteins as well as the blocked blood vessels can be traced back to factors like heart health and sleep quality, and have historically been attributed to a person’s lifestyle choices. 

But what about the factors we can’t control? What about external variables like where we live and the things we experience daily? 

If the human brain is essentially a sponge that absorbs information, then these external stimuli could have a cumulative effect on mental health over time.

Noise Pollution and Dementia

According to a 2021 study published in the British Medical Journal, a person’s living environment, specifically their daily sound exposure, is strongly associated with brain health and often correlates with dementia and Alzheimer’s disease. 

According to the researchers, residents whose houses or apartments are close to noisy, busy highways and railroads have an increased risk of developing dementia and dementia subtypes, especially Alzheimer’s disease. This is an especially relevant finding today because both Alzheimer’s cases and the percentage of the world population living in cities are increasing. 

The study by the British Medical Journal claims that by the year 2050, the number of people living with dementia will exceed 130 million. At present, roughly 50 million people live with the condition worldwide. So, if cases were to reach 130 million, that would represent a 160% increase over 30 years. 

At the same time, the United Nations projects that by the year 2050, the percentage of the world’s population living in urban centers will rise to 68% from the 56% that live in cities today. 

If both trends hold to be true, the effects of transportation noise on mental health could become even more evident, and widespread. Both noise pollution and dementia are already considered global health emergencies independent of one another. These two phenomena have now proven to be related, and their rising prevalence is likely to continue to compound.

As a point of reference, the level of near-constant traffic noise in these urban neighborhoods was comparable by researchers as “equivalent to noise levels in an open office environment and only 5 dB lower than a regular conversation between people at a distance of 1 m.” 

This is noise coming from trains and cars, both of which are potentially dangerous to humans and therefore can trigger an unconscious release of stress hormones in most people. This daily stress is a big part of what scientists are attributing to the onset of dementia. 

Influence of Transportation Noise on Mental Health 

Whether anxiety is a direct cause of dementia or merely an early indicator is yet to be conclusively proven. Studies have shown that adults with anxiety are more likely to develop dementia. Anxiety is associated with physiological symptoms such as poor heart health, a known precursor to cognitive decline. 

The harmful plaque that builds up in the brain in conditions like Alzheimer’s is commonly brought on by high blood pressure. Strokes brought on by poor heart health can also have catastrophic effects on the brain. 

As Dr. Seth Martin, a medical professor at Johns Hopkins University puts it, “There is increasing evidence connecting cardiovascular risk factors with brain health.” In other words, what affects your heart affects your head.

To clarify, isolated incidents of anxiety and panic, although they do spike your blood pressure, do not necessarily cause chronic hypertension. 

However, according to the Mayo Clinic, persistent, daily anxiety “can cause damage to your blood vessels, heart, and kidneys, as can chronic high blood pressure. In addition, people who are anxious or stressed are more likely to engage in unhealthy habits that can raise blood pressure.” 

Daily exposure to stimuli that trigger the release of stress hormones can cause a person to become anxious and lead to harmful effects for the brain. 

A 2019 paper published in the Annual Review of Public Health stated, “Cardiovascular risk factors and disease are linked with cognitive decline and dementia risk, suggesting that air pollution and noise exposure may contribute indirectly to cognitive decline and dementia risk by influencing vascular neuropathology.” 

Noise Pollution and Deep Sleep Impact on Dementia

A person’s sleep patterns can also be affected by long-term, consistent exposure to loud noises. And as we now know, deep sleep is needed to maintain good brain hygiene. During deep sleep, your brain flushes out waste to prevent the buildup of the plaque that blocks neural pathways (which could lead to Alzheimer’s). 

Since your brain “cleans itself” during deep sleep, then a lack of deep sleep means bad brain hygiene, i.e., an increased risk of harmful protein buildups. If people who live near train tracks or busy highways suffer from fragmented and shallow sleep patterns, then it makes sense that they also experience higher rates of cognitive decline. 

Even if the sound of trains, cars, and airplanes outside a person’s window fails to wake them up, it still could result in lower quality sleep. 

A study from Harvard University found that adults who slept fewer than 5 hours per night were twice as likely to develop dementia. However, regardless of the number of hours a person sleeps, if they’re not getting enough deep sleep, then their brain isn’t getting the recovery that it needs to function at its full potential. 

Noise Pollution: A Public Health Crisis

In Europe, noise pollution (regular exposure to elevated sound levels) is considered the second most severe environmental risk to public health, outranked only by air pollution. In the United States, noise pollution is an equally ubiquitous issue, especially in our urban centers. 

A 2021 statement from the American Environmental Protection Agency (EPA) said that noise pollution “adversely affects the lives of millions of people” in the US and “problems related to noise include stress-related illnesses, high blood pressure, speech interference, hearing loss, sleep disruption, and lost productivity.” Many of these factors can contribute to cognitive decline. 

When you think of the body as an interconnected system, it’s not hard to imagine how something that causes high blood pressure or sleep deprivation could eventually result in symptoms like memory loss or decreased productivity. When left unchecked for multiple decades, these problems could, and often do, ultimately lead to dementia.

Unfortunately, this is not an issue that individual people can solve alone. Soundproofing one’s home or moving to the suburbs is impractical and prohibitively expensive options for most people. 

Like air pollution, the problem of sound pollution is one that communities will likely have to tackle together. Increasing awareness about the adverse health effects that noise pollution causes will hopefully lead to legislative reform and infrastructure projects to reduce resident exposure to transportation noise. 

Taking good care of your mind is an ongoing, extensive endeavor that requires more than just a quiet living space. It requires a good diet, frequent physical and mental exercise, proper nutrition, stress management, and deep sleep. 

Protection from cognitive decline starts with awareness of its causes and following recommended prevention protocols.

As the Greek historian Plutarch said, the best way to live a prosperous life is to “arm yourself with knowledge against the blows of fortune.”