Blood pressure response to noise in children and adolescents

Hypertension, one of the major cardiovascular risk factors, is getting epidemic dimensions, although scientific organizations point out the role of traditional risk factors, such as obesity and physical inactivity, and take steps to regulate the continuously increase. It is estimated that the number of people with hypertension will increase 15%‐20% by 2025, reaching almost 1.5 billion. ¹ Recent data confirm that there is also a trend of increasing prevalence of childhood hypertension during the last 2 decades. ² Hypertensive children are reported to have increased risk to become hypertensive adults and may present early subclinical cardiovascular damage. ³ Hence, identifying further risk factors for hypertension presenting in childhood is more crucial than ever and of great importance for early prevention and treatment.

In the current issue of the Journal of Clinical Hypertension Badihian et al, provided intriguing evidence about the effect of noise and psychological distress on children's blood pressure from a large population sample in a cross‐sectional study performed in Iran. ⁴ The results suggested that there is a positive relationship between the level of noise annoyance and diastolic blood pressure, as well as with the mean arterial blood pressure. Moreover, children with high psychological distress had a 15% higher possibility to experience an increase in blood pressure levels. Even if the study contains nationally reported evidence, it is one of the first studies specifically focused on children and adolescents, assessing the relationship between noise annoyance and blood pressure levels and highlighting a new field for further research.

In the adult population, epidemiological evidence reporting the association between noise exposure and the incidence of cardiovascular diseases have recently increased but provides conflicting results. University students exposed to road traffic noise were found to have higher cardiovascular risk scores (Framingham and SCORE) compared to the unexposed population. ⁵ A meta‐analysis of 8 observational studies supported a positive, but not significant, association between noise annoyance and the risk of ischemic heart disease, although a strong relationship between noise and the risk of hypertension was revealed. ⁶ When noise was directly evaluated based to quantity, it seems that one decibel increase during daytime is related to increases in prevalence of cerebrovascular disease by 0.66%, hypertension by 0.17% and heart disease by 0.38%. ⁷ One of the biggest follow‐up studies at the field showed that 10 years exposure to road traffic noise was not associated with the prescription of antihypertensive drugs. A possible limitation of this study was the exclusion of diuretics from the reported antihypertensive drugs, which are usually prescribed for treatment of hypertension in clinical practice. ⁸

In the pediatric population, studies have been reported a small positive association between noise and blood pressure elevation. Increased noise population associated with traffic volume seems to increase both systolic and diastolic blood pressure. The prevalence of increased blood pressure values in preschool children were found to be 0.04 times increased in noisy areas compared to the quiet ones. This risk may seem small, but when systolic and diastolic values were separately analyzed there was a 5mmHg statistically significant increase in systolic blood pressure and 2 beats/min in heart rates. ⁹ A national German study reported 1 mm Hg and 0.6 mm Hg increase of systolic and diastolic blood pressure, respectively, in children aged 8‐14 years old, when the noise level was elevated by 10 decibels. In the same study, an increase in blood pressure levels was shown when noise was also reported as a factor of annoyance especially during nighttime. ¹⁰ Similar data have been reported either in low socioeconomic areas or after aircraft noise annoyance. ¹¹ , ¹² However, a recent meta‐analysis showed non‐significant increases in blood pressure at school/kindergarten or at home with traffic noise levels which was attributed to methodological variability among studies. ¹³ Longitudinal data on the effect on noise pollution on blood pressure in pediatric population are needed, aiming to further analyze this relationship.

Cognitive and emotional perception of noise may also have significant impact on the cardiovascular system. Noise annoyance may modify the effect of environmental noise pollution on the vessels could possibly accelerate vascular aging and presentation of hypertension. In the Hyena study, noise annoyance was reported to be a modifier in the relation between noise and hypertension. ¹⁴ In another study, investigating the effect of aircraft noise exposure, it has been demonstrated that noise exposure is associated with higher office and nighttime diastolic BP, arterial stiffness, and diastolic dysfunction of the left ventricle. ¹⁵ The increase in arterial stiffness was steeper in the exposed to noise participants and evident in ages young than 40 years presenting as early vascular aging and associated with noise annoyance in the normotensive participants. However, the effect of noise annoyance on blood pressure levels was not found in study patients with hypertension. Moreover, environmental noise may affect future generations by increasing the risk of pregnancy hypertension and especially preeclampsia. ¹⁶ Pregnancy complications associated with hypertension may result in vulnerable cohorts for future hypertension and cardiovascular complications.

Further investigation is needed in order to identify the potential links behind noise and hypertension. Psychological distress seems that it could also be a determinant for increased cardiovascular risk factors, such as hypertension and hypercholesterolemia. ¹⁷ Moreover, hypertensive individuals are vulnerable to psychological health issues that could exacerbate blood pressure elevation. Noise could be the first step of anxiety and depression or hyperactivity, leading to childhood hypertension. ¹⁸ However, recently published data showed no relationship between anxiety, depression, and cardiovascular risk factors in healthy young individuals. ¹⁹ On the other hand, noise is more frequently observed in low‐income areas, where economical disadvantages induce anxiety that could be a link to hypertension. ¹¹ Furthermore, noise during nighttime is positively associated with sleep disturbances in both children and adults, which could also explain elevation blood pressure after noise exposure. ²⁰ In conclusion, increasing evidence highlight a positive association between noise and increased blood pressure response in youth, but data are limited and no longitudinal studies exist.

CONFLICT OF INTEREST

None.

AUTHOR CONTRIBUTIONS

Both authors read and approved the final version of the submitted manuscript for publication.

Antza C, Stabouli S. Blood pressure response to noise in children and adolescents. J Clin Hypertens. 2020;22:1442–1443. 10.1111/jch.13951