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 cardiovascular 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. 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 Dr. 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
Dr. 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.