Exposure to road traffic noise and cognitive development in schoolchildren in Barcelona, Spain: A population-based cohort study

Outdoor air pollution, road traffic noise, and allostatic load in children aged 6-11 years: evidence from six European cohorts

Emerging evidence suggests that exposure to air pollutants and road traffic noise triggers stress responses, which mediate physiological responses in multiple organs and tissues. However, epidemiological study in children is sparse. We aimed to evaluate whether outdoor air pollution and road traffic noise are associated with physiological response measured by allostatic load in children. We studied 919 children aged 6-11 years from the HELIX (Human Early Life Exposome) cohort in 6 European countries with 19 biomarkers assessed in four physiological systems-cardiovascular, metabolic, immune/inflammation, and neuroendocrine systems. We then calculated both count-based and continuous scores for each physiological system and generated allostatic load scores (range 0-19). Exposure to air pollution (NO2, PM2.5, PM10, PM2.5absorbance) and road traffic noise (LDEN) based on participants' home, school, and commuting route addresses were estimated for the year prior to outcome assessment. Higher exposure to all air pollutants was associated with a higher allostatic load, although only the association of PM10 survived correction for multiple testing (for count-based allostatic load score: RR = 1.27, 95%CI: 1.08, 1.48; for continuous allostatic load score: β = 0.56, 95% CI: 0.27-0.84, per each 10 µg/m3 increase in PM10). Examining physiological systems separately, higher exposure to air pollution was mainly associated with higher allostatic load in the immune/inflammatory and metabolic systems. No associations between road traffic noise and allostatic load were observed. Our findings suggest that air pollution act as a chronic stressor in manifesting multi-systemic physiological dysregulation in childhood, which may be a precursor of air pollution-related diseases.

Long-Term Exposure to Traffic-Related Air Pollution and Noise and Dynamic Brain Connectivity across Adolescence

BACKGROUND

Traffic-related exposures, such as air pollution and noise, show long-term associations with brain alterations in children and adolescents. The associations with functional connectivity have been studied using static approaches of resting-state functional magnetic resonance imaging (rs-fMRI) (i.e., average connectivity between regions across the scanning session).

OBJECTIVES

Our aim was to investigate the long-term association of traffic air pollution and noise during pregnancy and childhood with functional connectivity across adolescence using a dynamic approach, which captures different connectivity patterns across the scanning session.

METHODS

We used data from the Generation R population-based birth cohort. We estimated levels of 14 air pollutants and traffic noise at home addresses during pregnancy and childhood. We acquired rs-fMRI data at the age-10 y and age-14 y visits. We included participants with rs-fMRI data in at least one visit and either air pollution data (n = 3,588 ) or noise data (n = 2,642 ). We used k-means clustering to identify five connectivity patterns, called "states," that reoccur over time and across subjects and visits. We calculated the mean time spent in each state for each participant and visit. We performed multi- and single-pollutant mixed effects models adjusted for socioeconomic and lifestyle variables, including the individual as random effect to test the associations between the exposures and the mean time spent in each state.

RESULTS

Exposure to nitrogen oxides, particulate matter (PM), and road-traffic noise was related to differences in the time spent in the connectivity states, both in the multi- and single-pollutant models. For instance, higher levels of exposure to PM with aerodynamic diameter between 2.5 μ m and 10 μ m (PM COARSE ) during pregnancy and higher noise exposure during childhood were associated with more time spent in a state in which the default-mode network, related to self-referential processes and mind-wandering, shows high connectivity.

DISCUSSION

Traffic-related exposures might be related to long-term alterations in brain functional network organization in adolescents. Further research should explore the potential impact of these differences on cognition and psychopathology. https://doi.org/10.1289/EHP14525.

The role of NLRP3 inflammasome-mediated neuroinflammation in chronic noise-induced impairment of learning and memory ability

BACKGROUND

Noise pollution pervades daily working and living environment, becoming a serious public health problem. In addition to causing auditory impairment, noise independently contributes to cognitive decline as a risk factor. Though neuroinflammation plays an important role in noise-induced cognitive deficits, the mechanisms underlying noise-induced neuroinflammation in the hippocampus are still poorly understood. Glial hyperactivation of the NLRP3 inflammasome contributes to various neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). However, whether the NLRP3 inflammasome plays a role in noise-induced cognitive impairment remains to be further investigated.

METHODS

Adult male Wistar rats were exposed to 100 dB white noise (4 h/day) for 30 days with or without injection of the NLRP3 inhibitor MCC950 (10 mg/kg/day). The Morris water maze (MWM) test and the open field test (OFT) were performed to evaluate learning and memory ability of rats. HE staining was used to explore hippocampal pathological changes, while immunohistochemical staining was employed to evaluate the number and morphology of microglia and astrocytes. The mRNA levels of the NLRP3 inflammasome in the hippocampus were examined by Real-time PCR. The protein levels of NLRP3 inflammasome, inflammatory cytokines, p-Tau-S396, and amyloid-β (Aβ) 42 in the hippocampus were examined by Western blot. Immunofluorescence was used to observe the distribution of NLRP3 in glial cells and neurons, and the assembly of the NLRP3 inflammasome.

RESULTS

We found that noise exposure induced learning and memory impairment in rats, mainly related to the activation of microglia and astrocytes in hippocampus region. Noise exposure increased the protein levels of p-Tau-S396, Aβ42, ionized calcium binding adapter molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), interleukin (IL)-1β, IL-18, and tumor necrosis factor-α (TNF-α) in hippocampus. Furthermore, the hippocampus of noise-exposed rats showed elevated protein levels of NLRP3, ASC and cleaved caspase-1. The co-labeled immunofluorescence levels of Iba-1 or GFAP with NLRP3 significantly increased in the dentate gyrus (DG) region of the hippocampus. NLRP3 inhibitor MCC950 intervention reversed chronic noise-induced activation of NLRP3 inflammasome, AD-like pathologies and impairment of learning and memory in rats.

CONCLUSIONS

The NLRP3 inflammasome-mediated neuroinflammation played an essential role in chronic noise-induced cognitive dysfunction. These results provide novel strategies for the prevention and treatment of cognitive deficits caused by chronic noise.

Road traffic noise exposure and its impact on health: evidence from animal and human studies-chronic stress, inflammation, and oxidative stress as key components of the complex downstream pathway underlying noise-induced non-auditory health effects

In heavily urbanized world saturated with environmental pollutants, road traffic noise stands out as a significant factor contributing to widespread public health issues. It contributes in the development of a diverse range of non-communicable diseases, such as cardiovascular diseases, metabolic dysregulation, cognitive impairment, and neurodegenerative disorders. Although the exact mechanisms behind these non-auditory health effects remain unclear, the noise reaction model centres on the stress response to noise. When exposed to noise, the body activates the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, leading to the secretion of stress hormones like catecholamines and cortisol. Prolonged exposure to noise-induced stress results in chronic inflammation and oxidative stress. This review underscores the role of inflammation and oxidative stress in the progression of noise-induced vascular dysfunction, disruption of the circadian rhythm, accelerated aging, neuroinflammation, and changes in microbiome. Additionally, our focus is on understanding the interconnected nature of these health outcomes: These interconnected factors create a cascade effect, contributing to the accumulation of multiple risk factors that ultimately lead to severe adverse health effects.

The Necessity of Taking Culture and Context into Account When Studying the Relationship between Socioeconomic Status and Brain Development

Decades of research has revealed a relationship between childhood socioeconomic status (SES) and brain development at the structural and functional levels. Of particular note is the distinction between income and maternal education, two highly correlated factors which seem to influence brain development through distinct pathways. Specifically, while a families' income-to-needs ratio is linked with physiological stress and household chaos, caregiver education influences the day-to-day language environment a child is exposed to. Variability in either one of these environmental experiences is related to subsequent brain development. While this work has the potential to inform public policies in a way that benefits children, it can also oversimplify complex factors, unjustly blame low-SES parents, and perpetuate a harmful deficit perspective. To counteract these shortcomings, researchers must consider sociodemographic differences in the broader cultural context that underlie SES-based differences in brain development. This review aims to address these issues by (a) identifying how sociodemographic mechanisms associated with SES influence the day-to-day experiences of children, in turn, impacting brain development, while (b) considering the broader cultural contexts that may differentially impact this relationship.

Correlation between Long-Term Exposure to Traffic Noise and Risk of Type 2 Diabetes Mellitus

OBJECTIVE

This study aimed to probe the correlation of long-term exposure to traffic noise with the risk of type 2 diabetes mellitus (T2DM).

METHODS

The data of 480 community residents collected from April 2017 to April 2018 were retrospectively analyzed. Exposure levels for traffic noise were defined using 24-h mean traffic noise. Logistic regression calculated the association between long-term exposure to traffic noise and the risk of T2DM.

RESULTS

Overall, 480 enrolled participants were divided into T2DM (n = 45) and non-T2DM (n = 435) groups. Participants with T2DM were older and more likely to be male, had higher BMI, and were frequent drinkers (P < 0.001). The T2DM group displayed higher exposure to traffic noise than the non-T2DM group (P < 0.001). According to quartiles of traffic noise, all participants were categorized into four groups: Q1 (<51.5 dB), Q2 (51.5-<53.9 dB), Q3 (53.9-<58.0 dB), and Q4 (≥58.0 dB). Prevalence of T2DM was 5.4% in Q1, 7.7% in Q2, 10.3% in Q3, and 14.1% in Q4 groups. Multifactor regression analysis showed that age, BMI, drinking history, and traffic noise exposure are risk factors for T2DM (P < 0.05), whereas sex does not seem to have a significant impact on T2DM (P > 0.05).

CONCLUSION

Long-term exposure to traffic noise may elevate the risk of T2DM. This suggests that long-term exposure to high levels of traffic noise can increase the incidence of diabetes mellitus, which deserves further consideration.

A Comprehensive Review of Auditory and Non-Auditory Effects of Noise on Human Health

OBJECTIVE

Excessive noise is unpleasant and induces several physiological and psychological effects. Noise pollution is a potential threat to humans, particularly those continuously exposed for extended periods throughout the day over many years. This review aims to examine the various auditory and non-auditory outcomes associated with prolonged exposure to noise pollution.

MATERIALS AND METHODS

The review utilized a combination of relevant keywords to search the electronic databases. After screening based on the applied selection criteria for title, abstract, and full text, 44 articles were finally selected for critical review.

RESULTS

We identified and analyzed research findings related to noise-induced hearing loss, tinnitus, and sleep disturbances along with non-auditory issues such as annoyance, cognitive impairments, and mental stress associated with cardiovascular disorders. Furthermore, the existing studies were compared and collated to highlight the unique challenges and significance of noise pollution as a distinctive environmental concern and to explore the ongoing efforts in its research and prevention, including the early detection and potential reversal of noise-induced hearing loss.

CONCLUSION

The fundamental health consequences of noise pollution underscore the need for extensive research encompassing emerging noise sources and technologies to establish a health management system tailored to address noise-related health concerns and reduce noise exposure risk among populations. Finally, further research is warranted to ensure improved measurement of noise exposure and related health outcomes, especially in the context of occupational noise.

A new perspective for evaluating the efficacy of tACS and tDCS in improving executive functions: A combined tES and fNIRS study

BACKGROUND

Executive function enhancement is considered necessary for improving the quality of life of patients with neurological or psychiatric disorders, such as attention-deficit/hyperactivity disorder, obsessive-compulsive disorder and Alzheimer's disease. Transcranial electrical stimulation (tES) has been shown to have some beneficial effects on executive functioning, but the quantification of these improvements remains controversial. We aimed to explore the potential beneficial effects on executive functioning induced by the use of transcranial alternating current stimulation (tACS)/transcranial direct current stimulation (tDCS) on the right inferior frontal gyrus (IFG) and the accompanying brain function variations in the resting state.

METHODS

We recruited 229 healthy adults to participate in Experiments 1 (105 participants) and 2 (124 participants). The participants in each experiment were randomly divided into tACS, tDCS, and sham groups. The participants completed cognitive tasks to assess behavior related to three core components of executive functions. Functional near-infrared spectroscopy (fNIRS) was used to monitor the hemodynamic changes in crucial cortical regions in the resting state.

RESULTS

Inhibition and cognitive flexibility (excluding working memory) were significantly increased after tACS/tDCS, but there were no significant behavioral differences between the tACS and tDCS groups. fNIRS revealed that tDCS induced decreases in the functional connectivity (increased neural efficiency) of the relevant cortices.

CONCLUSIONS

Enhancement of executive function was observed after tES, and the beneficial effects of tACS/tDCS may need to be precisely evaluated via brain imaging indicators at rest. tDCS revealed better neural benefits than tACS during the stimulation phase. These findings might provide new insights for selecting intervention methods in future studies and for evaluating the clinical efficacy of tES.

Relationship Between Work-Related Noise Exposure and Cognitive Impairment: A Cross-Sectional Study in China

Background

Noise exposure and the risk of cognitive impairment are currently major public health issues.

Objective

This study aimed to analyze the relationship between noise exposure and early impairment of cognitive function from the perspective of occupational epidemiology and to provide evidence for the long-term prevention and treatment of dementia in the context of aging.

Methods

This study was conducted in China between May and August 2021. The independent variables were the type of hazardous factors, duration of noise exposure, perceived noise intensity, and cumulative noise exposure (CNE). The dependent variable was cognitive function, which was measured using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Multiple linear and logistic regression were used to analyze the relationship between noise exposure and cognitive function and to establish an effect curve.

Results

The detection rates of cognitive dysfunction using the MMSE and MoCA were 1.1% and 36.2%, respectively. The predicted MMSE and MoCA scores showed a downward trend within the CNE value ranging from 90-140 dB.time. Each unit increase in CNE decreased cognitive function scores by 0.025 (0.037, 0.013) and 0.020 (0.037, 0.003) points,respectively.

Conclusions

From the perspective of occupational epidemiology, these findings reveal a potential link between long-term noise exposure and early cognitive impairment.

Association between residential exposure to road traffic noise and cognitive and motor function outcomes in children and preadolescents

BACKGROUND

Exposure to environmental noise is increasing in recent years but most of the previous literature in children has evaluated the effect of aircraft noise exposure at schools on cognition.

OBJECTIVE

To assess whether residential exposure to road traffic noise during pregnancy and childhood is associated with cognitive and motor function in children and preadolescents.

METHODS

The study involved 619 participants from the Spanish INMA-Sabadell cohort and 7,115 from the Dutch Generation R Study. We used noise maps to estimate the average day-evening-night road traffic noise levels at each participant's residential address during pregnancy and childhood periods. Validated tests were administered throughout childhood in both cohorts to assess non-verbal and verbal intelligence, memory, processing speed, attentional function, working memory, cognitive flexibility, risky decision-making, and fine and gross motor function. Linear models, linear mixed models, and negative binomial models were run depending on the outcome in cohort-specific analysis and combined with a random-effects meta-analysis. All models were adjusted for several socioeconomic and lifestyle variables and results corrected for multiple testing.

RESULTS

Average road traffic noise exposure levels during pregnancy and childhood were 61.3 (SD 6.0) and 61.5 (SD 5.4) dB for the INMA-Sabadell cohort and 54.6 (SD 7.9) and 53.5 (SD 6.5) dB for the Generation R Study, respectively. Road traffic noise exposure during pregnancy and childhood was not related to any of the cognitive and motor function outcomes examined in this study (e.g. -0.92 (95 % CI -2.08; 0.24) and 0.20 (95 % CI -0.96; 1.35) in overall estimates of memory and fine motor function, respectively, when road traffic noise increases by 10 dB during childhood).

CONCLUSIONS

These findings suggest that child's cognitive or motor functions are not affected by residential exposure to road traffic noise. However, more studies evaluating this association at school and home settings as well as noise events are needed.

The effects of exposure to road traffic noise at school on central auditory pathway functional connectivity

As the world becomes more urbanized, more people become exposed to traffic and the risks associated with a higher exposure to road traffic noise increase. Excessive exposure to environmental noise could potentially interfere with functional maturation of the auditory brain in developing individuals. The aim of the present study was to assess the association between exposure to annual average road traffic noise (LAeq) in schools and functional connectivity of key elements of the central auditory pathway in schoolchildren. A total of 229 children from 34 representative schools in the city of Barcelona with ages between 8 and 12 years (49.2% girls) were evaluated. LAeq was obtained as the mean of 2-consecutive day measurements inside classrooms before lessons started following standard procedures to obtain an indicator of long-term road traffic noise levels. A region-of-interest functional connectivity Magnetic Resonance Imaging (MRI) approach was adopted. Functional connectivity maps were generated for the inferior colliculus, medial geniculate body of the thalamus and primary auditory cortex as key levels of the central auditory pathway. Road traffic noise in schools was significantly associated with stronger connectivity between the inferior colliculus and a bilateral thalamic region adjacent to the medial geniculate body, and with stronger connectivity between the medial geniculate body and a bilateral brainstem region adjacent to the inferior colliculus. Such a functional connectivity strengthening effect did not extend to the cerebral cortex. The anatomy of the association implicating subcortical relays suggests that prolonged road traffic noise exposure in developing individuals may accelerate maturation in the basic elements of the auditory pathway. Future research is warranted to establish whether such a faster maturation in early pathway levels may ultimately reduce the developing potential in the whole auditory system.

School-Based Interventions to Support Healthy Indoor and Outdoor Environments for Children: A Systematic Review

Environmental exposures are associated with children's health. Schools are often urban exposure 'hotspots' for pollution, noise, lack of green space and un-walkable built environments. The aim of this systematic review was to explore the impact of school-based interventions on the modification of indoor and outdoor stressors related to the built and natural environment on children's exposure and health. A systematic review of seven databases was performed. We included quantitative studies on children aged 5-12, which reported intervention delivered within school settings aimed at addressing key environmental exposures including air pollution, green spaces, traffic noise or active travel; and reported physical and mental health, physical activity or active travel behavior. The quality of studies was assessed and interventions were described using a standardized framework. A narrative synthesis approach was used to describe the findings. Thirty-nine papers were included on three main intervention types: improve indoor air quality by the increase of ventilation rates in classrooms; increase children's green time or greening schools, and multicomponent interventions to increase active travel to school by changes in pedestrian facilities. No eligible intervention to reduce traffic noise at school was found. Increasing ventilation rates improved short-term indoor air quality in classrooms, but the effect on cognitive performance was inconsistent. Greening schools and increasing children's green time have consistent positive effects on cognition and physical activity, but not in behavior. Multi-component interventions can increase walking and cycling after three years. Overall, the studies were rated as having poor quality owing to weak study designs. We found modest evidence that school-based built and natural environment interventions can improve children's exposure and health.

Environmental Noise Exposure and Sleep Habits among Children in a Cohort from Northern Spain

Environmental noise is considered the second most serious environmental risk factor in Europe. However, little evidence exists regarding its impact on health and sleep in children, and the results are inconclusive. In this study, we aim to analyse the effect of environmental noise exposure on 11-year-old children's sleep habits. Data were collected from 377 participants in the INMA-Gipuzkoa (INfancia y Medio Ambiente) cohort project using both parent-reported and actigraphic sleep measures. The results revealed that 60% of children have a day-evening-night environmental noise exposure (Lden) of above 55 dB, which is defined as a "high noise level". No differences in noise exposure were observed between different socioeconomic groups. However, no effect of environmental noise was found on sleep variables. The paper highlights the importance of studying how environmental noise may affect children's sleep.