Data Underscore Negative Health Effects of Traffic Noise

New research by Thomas Münzel, MD, senior professor of cardiology at Johannes Gutenberg University Mainz in Mainz, Germany, and colleagues again emphasized the harmful effects of noise on the heart and blood vessels. An analysis of current epidemiologic data provided strong indications that transportation noise is closely related to cardio- and cerebrovascular diseases, according to a statement on the data analysis. The results were published in Circulation Research.

Morbidity and Mortality

Epidemiologic studies have shown that road, rail, or air traffic noise increases the risk for cardiovascular morbidity and mortality, with strong evidence for ischemic heart disease, heart failure, and stroke, according to the scientists. The World Health Organization reported that at least 1.6 million healthy life years are lost annually in Western Europe because of traffic-related noise. Nighttime traffic noise leads to sleep fragmentation and shortening, an increase in stress hormone levels, and increased oxidative stress in the vessels and brain. These factors could favor vascular (endothelial) dysfunction, inflammation, and hypertension, thereby increasing cardiovascular risk.

Consequences and Pathomechanisms

In the current publication, the authors provided an overview of epidemiologic research on the effects of transportation noise on cardiovascular risk factors and diseases, discussed mechanistic insights from the latest clinical and experimental studies, and proposed new risk markers to address noise-induced cardiovascular effects in the general population. An integrated analysis in the article demonstrated that for every 10 dB(A) increase, the risk for cardiovascular diseases such as heart attack, stroke, and heart failure significantly increases by 3.2%.

The authors also explained the possible effects of noise on changes in gene networks, epigenetic pathways, circadian rhythms, signal transmission along the neuronal-cardiovascular axis, oxidative stress, inflammation, and metabolism. Finally, current and future noise protection strategies are described, and the existing evidence on noise as a cardiovascular risk factor is discussed.

Confirmed Cardiovascular Risk Factor

“As an increasing proportion of the population is exposed to harmful traffic noise, efforts to reduce noise and laws for noise reduction are of great importance for future public health,” said Münzel. “It is also important for us that due to the strong evidence, traffic noise is finally recognized as a risk factor for cardiovascular diseases.”

Heart Attack Outcomes

Münzel and other researchers from Mainz have been studying the cardiovascular consequences of air pollution and traffic noise for several years. For example, they found that heart attacks in people and animals exposed to high noise levels earlier in life healed poorly. These results were published last year in Cardiovascular Research. According to the authors, the findings suggest that traffic noise may play a significant role in the development and course of coronary heart disease, such as after a heart attack.

The scientists initially found in animal experiments that exposure to aircraft noise for 4 days led to increased inflammation in the vessels. Compared with mice not exposed to aircraft noise, the noise-exposed animals showed an increase in free radicals; these animals exhibited a significant inflammatory response and had impaired vessel function.

The researchers explained that the experimental data showed aircraft noise alone triggers a proinflammatory transcription program that promotes the infiltration of immune cells into cardiovascular tissue in animals with acute myocardial infarction. They noted an increased infiltration of CD45+ cells into the vessels and heart, dominated by neutrophils in vessel tissue and Ly6Chigh monocytes in heart tissue. This infiltration creates a proinflammatory milieu that adversely affects the outcome after myocardial infarction by predisposing the heart tissue to greater ischemic damage and functional impairment. Exposure of animals to aircraft noise before induction of myocardial infarction by left anterior descending (LAD) coronary artery ligation impaired left ventricular function and increased infarct size after cardiac ischemia. In addition, noise exposure exacerbated infarct-induced endothelial dysfunction of peripheral vessels as early as 24 hours after LAD ligation.

Clinical Confirmation

These experimental results were confirmed by observations in the population-based Gutenberg Health Study. The researchers analyzed data from 100 patients with heart attack. The lead and senior authors of the study Michael Molitor, MD, and Philip Wenzel, MD, of the University of Mainz, explained, “From our studies, we have learned that exposure to aircraft noise before a heart attack significantly amplifies subsequent cardiovascular inflammation and exacerbates ischemic heart failure, which is favored by inflammation-promoting vascular conditioning. Our translational results show that people who have been exposed to noise in the past have a worse course if they experience a heart attack later in life.”

Study participants who had experienced a heart attack in their medical history had elevated levels of C-reactive protein if they had been exposed to aircraft noise in the past and subsequently developed noise annoyance reactions (0.305 vs 1.5; P = .0094). In addition, left ventricular ejection fraction in these patients after a heart attack was worse than that in patients with infarction without noise exposure in their medical history (62.5 vs 65.6; P = .0053).

The results suggest that measures to reduce environmental noise could help improve the clinical outcomes of heart attack patients, according to the authors.

Mental Health Effects

Traffic noise also may be associated with an increased risk for depression and anxiety disorders, as reported 2 years ago by the German Society for Psychosomatic Medicine and Medical Psychotherapy. Evolution has programmed the human organism to perceive noises as indicators of potential sources of danger — even during sleep. “Noise puts the body on alert,” explained Manfred Beutel, MD, director of the Clinic for Psychosomatic Medicine and Psychotherapy at the University of Mainz. As a result, the autonomic nervous system activates stress hormones such as adrenaline and cortisol, leading to an increase in heart rate and blood pressure. If noise becomes chronic, chronic diseases can develop. “Indeed, observational and experimental studies have shown that persistent noise annoyance promotes incident hypertension, cardiovascular diseases, and type 2 diabetes,” said Beutel.

Depression Risk Doubled

Among the negative effects of noise annoyance are also mental illnesses, as has become increasingly clear. “Noise annoyance disrupts daily activities and interferes with feelings and thoughts, sleep, and recovery,” said Beutel. The interruptions trigger negative emotional reactions such as anger, distress, exhaustion, flight impulses, and stress symptoms. “Such conditions promote the development of depression over time,” said Beutel. This observation was confirmed by the large-scale Gutenberg Health Study using the example of the Mainz population, which suffers to a large extent from noise annoyance because of the nearby Frankfurt Airport. “With increasing noise annoyance, the rates of depression and anxiety disorders steadily increased, until the risks eventually doubled with extreme annoyance,” said Beutel. Other studies point in the same direction. For example, a meta-analysis found a 12% increase in the risk for depression per 10-dB increase in noise. Another study found an association between nocturnal noise annoyance and the use of antidepressants.

Fine Particulate Matter

According to an evaluation of the Gutenberg Study, people perceive noise annoyance from aircraft noise as the most pronounced, followed by road, neighborhood, industrial, and railway noise. Noise occurs most frequently in urban areas that also produce air pollution such as fine particulate matter. “Fine particulate matter is also suspected of promoting anxiety and depression,” said Beutel, “because the small particles of fine particulate matter can enter the bloodstream and trigger inflammatory processes there, which in turn are closely related to depression.”

This story was translated from Univadis Germany, which is part of the Medscape professional network, using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.

Source link

error: Content is protected !!