Longitudinal effects of environmental noise and air pollution exposure on autism spectrum disorder and attention-deficit/hyperactivity disorder during adolescence and early adulthood: The TRAILS study

Particulate matter 2.5 (PM2.5) - associated cognitive impairment and morbidity in humans and animal models: a systematic review

Particulate matter with an aerodynamic diameter of less than 2.5 µm (PM2.5) is one of the criteria air pollutants that (1) serve as an essential carrier of airborne toxicants arising from combustion-related events including emissions from industries, automobiles, and wildfires and (2) play an important role in transient to long-lasting cognitive dysfunction as well as several other neurological disorders. A systematic review was conducted to address differences in study design and various biochemical and molecular markers employed to elucidate neurological disorders in PM2.5 -exposed humans and animal models. Out of 340,068 scientific publications screened from 7 databases, 312 studies were identified that targeted the relationship between exposure to PM2.5 and cognitive dysfunction. Equivocal evidence was identified from pre-clinical (animal model) and human studies that PM2.5 exposure contributes to dementia, Parkinson disease, multiple sclerosis, stroke, depression, autism spectrum disorder, attention deficit hyperactivity disorder, and neurodevelopment. In addition, there was substantial evidence from human studies that PM2.5 also was associated with Alzheimer's disease, anxiety, neuropathy, and brain tumors. The role of exposome in characterizing neurobehavioral anomalies and opportunities available to leverage the neuroexposome initiative for conducting longitudinal studies is discussed. Our review also provided some areas that warrant consideration, one of which is unraveling the role of microbiome, and the other role of climate change in PM2.5 exposure-induced neurological disorders.

Connecting the dots: environmental pollution and Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by challenges in social communication and repetitive behavior. While the exact etiology of ASD remains elusive, researchers have increasingly turned their attention to the role of environmental factors in its development. Among these factors, environmental pollution has emerged as a potential contributor to the rising prevalence of ASD cases worldwide. This review delves into the growing body of scientific evidence suggesting a significant association between environmental pollution and the risk of ASD. It explores the environmental pollution that have been implicated, including air pollution, water contaminants, heavy metals, pesticides, and endocrine-disrupting chemicals. The detrimental impact of these pollutants on the developing brain, particularly during critical periods of gestation and early childhood has been discussed. This will provide insights into the possible mechanisms by which the various pollutants may influence the neurodevelopmental pathways underlying ASD. Additionally, the potential interplay between genetic susceptibility and environmental exposure is explored to better understand the multifactorial nature of ASD causation. Considering the alarming increase in ASD prevalence and the ubiquity of environmental pollutants, this review emphasizes the urgent need for further investigation and the adoption of comprehensive preventive measures.

Postpartum Depression Increases the Risk of Childhood Attention Deficit Hyperactivity Disorder Diagnosis

Postpartum Depression (PPD) is a common adverse pregnancy outcome, but the extent to which PPD correlates with attention deficit hyperactivity disorder (ADHD) in the offspring is unclear. Therefore, we examined if children of mothers who experienced PPD are at risk for developing ADHD and how this association may be modified by the child's sex, race/ethnicity, and gestational age at delivery. A retrospective cohort study of singleton-born children aged 3-12 years and delivered in Kaiser Permanente Southern California hospitals between 01/01/2010-12/31/2019 (n = 229,860) was performed using electronic health records. ICD- 9-CM and ICD- 10-CM codes and pharmacy records were used to ascertain exposure and outcomes of interest. Incidence rates and adjusted hazard ratios (aHR) were estimated to quantify the association between PPD and childhood ADHD. Children of women with PPD were more likely to be diagnosed with ADHD than children of women without PPD (8.85 vs. 5.18/1000 person-years, aHR = 1.76, confidence interval (CI): 1.66-1.86). Among women who delivered at 29-32 and 33-36 weeks of gestation, PPD was associated with 1.61-fold (95% CI: 1.06-2.57) and 1.72-fold (95% CI: 1.44-2.06) increased risk of ADHD, respectively, compared to pregnancies without a history of PPD. PPD was associated with an increased ADHD risk for all racial/ethnic groups and both child sex categories. PPD may help identify at-risk children who could benefit from earlier surveillance and interventions. Additional studies are needed to determine if PPD has a causal relationship with ADHD or if these conditions have a common risk factor.

Exposure to different types of residential greenness during pregnancy and early childhood and attention-deficit/hyperactivity disorder diagnosis: A nested case-control study

BACKGROUND

Epidemiological studies suggest that exposure to greenness may protect children attention-deficit/hyperactivity disorder (ADHD) diagnosis. However, evidence to date is limited while no previous research has independently investigated exposure to prenatal greenness.

OBJECTIVE

We conducted a nested case-control study with data from Born in Bradford (BiB) and INfancia y Medio Ambiente (INMA) birth cohorts to investigate the association between exposure to various types of residential greenness and ADHD diagnosis, considering both pregnancy and early childhood exposure periods independently. PM2.5 was tested as a potential mediator of the association.

METHODS

Children with ADHD were identified based on a confirmed medical diagnosis. Pregnancy and early childhood exposure to residential greenness were estimated through Normalized Difference Vegetation Index (NDVI) within 300-m, urban green space and natural green space percentages within 300-m, and the linear distance to the closest green space in meters. We performed a conditional logistic regression to analyze the association between the included greenness metrics and ADHD.

RESULTS

We found no statistically significant associations between any of the pregnancy and early childhood greenness metrics and ADHD diagnosis in the BiB cohort. Further analysis on the INMA cohort found that higher urban green space percentage slightly increased the risk of ADHD diagnosis during both pregnancy (total effects: OR 1.04, 95 % CI 1.01 to 1.07, p = 0.012; direct effects: OR 1.06, 95 % CI 1.03 to 1.10, p < 0.001) and early childhood (total effects: OR 1.03, 95 % CI 1.00 to 1.07, p = 0.042; direct effects: OR 1.04, 95 % CI 1.00 to 1.07, p = 0.033). However, these associations were not supported by the sensitivity analyses.

CONCLUSIONS

This study found both null and inconsistent associations between the included greenness metrics and ADHD. Further research is warranted to elucidate the potential role of exposure to different types of greenness in ADHD diagnosis.

Urban air pollution and child neurodevelopmental conditions: a systematic bibliometric review

PURPOSE OF REVIEW

Using advanced bibliometric analysis, we systematically mapped the most current literature on urban air pollution and neurodevelopmental conditions to identify key patterns and associations. Here, we review the findings from the broader literature by discussing a distilled, validated subset of 44 representative studies.

RECENT FINDINGS

Literature highlights a complex relationship between environmental toxins, neurodevelopmental disorders in children, and neurobehavioral pathways involving oxidative stress, neuroinflammation, and protein aggregation. Chronic prenatal and postnatal exposure to airborne pollutants - such as particulate matter and heavy metals - may contribute to early formation of amyloid plaques through preadolescence. These processes may compromise synaptic plasticity and neural integrity, which can progressively induce cognitive, emotional, and behavioral dysregulation, sharing some pathological features traditionally associated with adult neurodegenerative diseases.

SUMMARY

The interactions between air pollution exposure levels, developmental timing, and factors such as genetic vulnerability associated with neurodevelopmental disorders are still undetermined. However, accelerated neurodegenerative processes leading to cognitive decline and suboptimal mental health in children and adolescents seem most likely linked with pollutants penetrating the blood-brain barrier, and inducing oxidative stress and neuroinflammation. Urgent precautionary action might reduce environmental exposures during critical early developmental periods, thereby safeguarding children's cognitive function and mental health.

The association between anthropogenic heat and parent-report symptoms of childhood attention deficit hyperactivity disorder in China: A novel perspective reflecting climate change

Anthropogenic climate change will have a negative impact on worldwide well-being over and above the direct consequences of rising average temperatures. But anthropogenic heat (AH) relationship with childhood attention deficit hyperactivity disorder (ADHD) is unknown. To assess the relationship with AH exposure and childhood ADHD symptoms in the context of global climate change, this study was conducted in a cross-sectional survey from April 2012 to May 2018 in the northeastern, northwestern, and southern regions of China, with a total enrollment of 179,846 children aged 6-18 years. Exposure to AH was evaluated by gathering socioeconomic and energy usage data along with nighttime light data from satellites and data on the Normalized Difference Vegetation Index. This encompassed four types of AH exposure: industrial processes, transportation, buildings, and human metabolism. The statistical analysis used generalized linear mixed-effects modeling to determine the association between the types of AH exposure and childhood ADHD symptoms. The mean (SD) age of the 179,846 study participants was 11.7 (2.9) years, and 7343 participants (4.1%) had ADHD symptoms. In adjusted models, increased levels of AH exposure per IQR from total AH, industry, transportation, buildings, and human metabolism all increased the odds of ADHD (odds ratios, 3.60 [95% CI, 3.42, 3.80]; 5.71 [95% CI, 5.32, 6.14]; 1.79 [95% CI, 1.75, 1.84]; 2.10 [95% CI, 2.03, 2.17]; 1.95 [95% CI, 1.89, 2.02]). The association remained robust after various sensitivity analyses. Prolonged exposure to AH is associated with the development of ADHD symptoms in children.

Ozone concentration, physical activity, and emotional and behavioral problems in children and adolescents

BACKGROUND

No prior study has examined the mutual association of long-term outdoor ozone (O3) concentration and physical activity (PA) with emotional and behavioral problems (EBPs) in children and adolescents. This study aims to investigate the association between long-term outdoor O3 concentration and the risk of EBPs in children and adolescents and further explore whether increased PA levels modify this association.

METHODS

Data were obtained from the 2020 wave follow-up examination of an ongoing prospective cohort study (COHERENCE project) in Guangzhou, China. A total of 419,033 children aged 6-17-year-old were included. Annual average outdoor O3 concentrations were obtained from the China High Air Pollutants (CHAP) dataset based on participants' residential addresses. PA levels were identified using the International Physical Activity Questionnaire Short Form (IPAQ). EBPs were assessed by the Chinese Parent-Report Strengths and Difficulties Questionnaire (SDQ-P).

RESULTS

Each interquartile range (IQR) increase in outdoor O3 concentration was associated with an increased odds ratio (OR) for abnormal emotional problems (OR: 1.024, 95% CI: 1.010-1.038), conduct problems (OR: 1.015, 95% CI: 1.002-1.029), peer relationship problems (OR: 1.029, 95% CI: 1.006-1.052), prosocial behavior (OR: 1.023, 95% CI: 1.012-1.034), total difficulties (OR: 1.024, 95% CI: 1.010-1.038), and internalizing behavior (OR: 1.039, 95% CI: 1.026-1.053), in fully adjusted models. The highest OR for abnormal EBPs was observed in children with low PA levels, in combination with high O3 concentration.

CONCLUSION

This study identified that long-term outdoor O3 concentration is associated with an increased risk of EBPs in children and adolescents, with higher PA levels attenuating these risks.

Particulate matter induced cognitive impairments via endoplasmic reticulum stress-mediated damage to mitochondria-associated endoplasmic reticulum membranes in immature rats

Particulate matter (PM) exposure has been increasingly recognized as detrimental to cognitive function and is associated with neurodevelopmental disorders. Mitochondria-associated endoplasmic reticulum membranes (MAMs) form an integrated interface between mitochondria and the endoplasmic reticulum (ER), facilitating crucial cellular functions. Prolonged ER stress (ERS) is implicated in various pathological states in the nervous system. MAMs and ERS may play vital roles in adverse effects of early-life PM exposure on cognitive abilities. This study investigated whether ERS plays a role in PM-induced MAMs dysfunction, leading to neuronal damage and cognitive impairments in early postnatal rats. Using a rat model with PM exposure concentrations of 2 and 10 mg/kg from postnatal Day 3 (PND3) to PND28, we observed that PM exposure resulted in anxiety-like behavior and impaired spatial working memory. The protein levels of ERS markers, including GRP78 and CHOP, were significantly increased in response to PM exposure. Western blot, transmission electron microscopy (TEM), and immunofluorescence analyses revealed decreased MAMs-related proteins and disrupted MAM structure and function caused by PM exposure. Administration of the ERS inhibitor 4-phenylbutyric acid (4-PBA) ameliorated these effects, restoring MAMs integrity and improving cognitive deficits. These findings highlighted the key role of ERS-MAMs dysfunction in PM-induced neurotoxicity and cognitive impairments, providing a new perspective and strategy for the prevention of cognitive deficits in early age with PM exposure.

Association Between Ambient Air Pollution and Attention-Deficit/Hyperactivity Disorder (ADHD) in Children: A Systematic Review and Meta-Analysis

The objective of this systematic review and meta-analysis was to assess the association between postnatal exposure to ambient air pollutants (particulate matter (PM)2.5, PM10, nitrogen dioxide (NO2)) and the risk of attention-deficit/hyperactivity disorder (ADHD) in children. Observational studies, including cohort, case-control, and cross-sectional designs, that examined the relationship between postnatal exposure to ambient air pollution and ADHD in children were included, while studies focusing on prenatal exposure or unrelated neurodevelopmental outcomes were excluded. A comprehensive search of databases including PubMed, Web of Science, Embase, and Ovid, last updated in May 2024, was conducted. The risk of bias in the selected studies was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools, with discrepancies resolved through discussion among four reviewers. A meta-analysis was performed, synthesizing results using hazard ratios (HR), odds ratios (OR), and risk ratios (RR) as effect sizes. Random effects models were applied in most analyses due to the expected variability between studies, while fixed effects models were employed where only two studies were available. A total of 25 studies were included, with sample sizes ranging from 174 to 35,103 children. The studies were conducted in different countries and varied in their design and pollutant exposure measurement methods. The meta-analysis demonstrated a significant association between PM2.5 exposure and ADHD, with moderate heterogeneity (I² = 74.2%). PM10 exposure was also significantly associated with ADHD, and the heterogeneity was reduced to 34.94% after excluding an influential outlier. NO2 exposure similarly showed a significant association with ADHD, with low heterogeneity (I² = 0%). Due to the limited number of studies per pollutant (ranging from two to six), publication bias was not assessed. Despite the significant findings, there were limitations, including moderate to high heterogeneity among studies and the small number of studies per pollutant, which restricted the ability to assess publication bias and impacted the robustness of the results. Differences in exposure measurement methods and study designs also contributed to variability in the findings. Nonetheless, the evidence suggests that postnatal exposure to ambient air pollutants, particularly PM2.5, PM10, and NO2, is significantly associated with an increased risk of ADHD in children. These results underscore the importance of conducting further large-scale, high-quality studies to explore these associations in greater depth and to elucidate the mechanisms underlying the link between air pollution and ADHD.

Environmental pollutants as risk factors for autism spectrum disorders: a systematic review and meta-analysis of cohort studies

BACKGROUND

Autism Spectrum Disorder (ASD) is a lifelong neurodevelopmental condition affecting communication, social interaction, and behavior. Evidence suggests that environmental pollutants are associated with ASD incidence. This review aimed to analyze the effect of environmental pollutants on ASD.

METHODS

Systematic review and meta-analysis of cohort studies evaluated the association between exposure to environmental pollutants and ASD. We searched COCHRANE CENTRAL, MEDLINE, CINAHL, LILACS, EMBASE, PsycINFO, Web of Science, SciELO, and gray literature from inception to January 2023. The model used for meta-analysis was inverse variance heterogeneity (IVhet). The effect measures were the beta coefficient (β) and the relative risk (RR) with their 95% confidence intervals (95% CI). Sensitivity analyses were carried out using an instrument to screen or diagnose autism.

RESULTS

A total of 5,780 studies were identified; 27 were included in the systematic review, and 22 were included in the meta-analysis. These studies included 1,289,183 participants and 129 environmental pollutants. Individual meta-analyses found a significant association between nitrogen dioxide RR = 1.20 (95% CI: 1.03 to 1.38; I2: 91%), copper RR = 1.08 (95% CI: 1.03 to 1.13; I2: 0%), mono-3-carboxy propyl phthalate β = 0.45 (95% CI: 0.20 to 0.70; I2: 0%), monobutyl phthalate β = 0.43 (95% CI: 0.13 to 0.73; I2: 0%) and polychlorinated biphenyl (PCB) 138 RR = 1.84 (95% CI: 1.14 to 2.96; I2:0%) with ASD. Subgroup meta-analyses found a significant association with carbon monoxide RR = 1.57 (95% CI: 1.25 to 1.97; I2: 0%), nitrogen oxides RR = 1.09 (95% CI: 1.04 to 1.15; I2: 34%) and metals RR = 1.13 (95% CI: 1.01 to 1.27; I2:24%).

CONCLUSION

This study found positive associations nitrogen dioxide, copper, mono-3-carboxypropyl phthalate, monobutyl phthalate, and PCB 138, and the development of ASD, likewise, with subgroups of pollutants carbon monoxide, nitrogen oxides, and metals. Therefore, it is important to identify these risk factors in children and adolescents to contribute to ASD and identify prevention strategies effectively.

Environmental pollution and extreme weather conditions: insights into the effect on mental health

Environmental pollution exposures, including air, soil, water, light, and noise pollution, are critical issues that may implicate adverse mental health outcomes. Extreme weather conditions, such as hurricanes, floods, wildfires, and droughts, may also cause long-term severe concerns. However, the knowledge about possible psychiatric disorders associated with these exposures is currently not well disseminated. In this review, we aim to summarize the current knowledge on the impact of environmental pollution and extreme weather conditions on mental health, focusing on anxiety spectrum disorders, autism spectrum disorders, schizophrenia, and depression. In air pollution studies, increased concentrations of PM2.5, NO2, and SO2 were the most strongly associated with the exacerbation of anxiety, schizophrenia, and depression symptoms. We provide an overview of the suggested underlying pathomechanisms involved. We highlight that the pathogenesis of environmental pollution-related diseases is multifactorial, including increased oxidative stress, systematic inflammation, disruption of the blood-brain barrier, and epigenetic dysregulation. Light pollution and noise pollution were correlated with an increased risk of neurodegenerative disorders, particularly Alzheimer's disease. Moreover, the impact of soil and water pollution is discussed. Such compounds as crude oil, heavy metals, natural gas, agro-chemicals (pesticides, herbicides, and fertilizers), polycyclic or polynuclear aromatic hydrocarbons (PAH), solvents, lead (Pb), and asbestos were associated with detrimental impact on mental health. Extreme weather conditions were linked to depression and anxiety spectrum disorders, namely PTSD. Several policy recommendations and awareness campaigns should be implemented, advocating for the advancement of high-quality urbanization, the mitigation of environmental pollution, and, consequently, the enhancement of residents' mental health.

Epigenetic regulation by KDM5A mediates the effects of prenatal PM2.5 exposure on hippocampal development and synaptic integrity through the Shh signaling pathway

Prenatal environmental exposure could be an essential health risk factor associated with neurodevelopmental disorders in offspring. However, the exact mechanisms underlying the impact of prenatal PM2.5 exposure on offspring cognition remain unclear. In our recent study using a PM2.5 exposed pregnant mouse model, we observed significant synaptic dysfunction in the hippocampi of the offspring. Concurrently, the epigenetic regulator of KDM5A and the Shh signaling pathway exhibited decreased activities. Significantly, changes in hippocampal KDM5A and Shh levels directly correlated with PM2.5 exposure intensity. Subsequent experiments revealed a marked reduction in the expression of Shh signaling and related synaptic proteins when KDM5A was silenced in cells. Notably, the effects of KDM5A deficiency were reversed significantly with the supplementation of a Shh activator. Furthermore, our findings indicate that Shh activation significantly attenuates PM2.5-induced synaptic impairments in hippocampal neurons. We further demonstrated that EGR1, a transcriptional inhibitor, plays a direct role in KDM5A's regulation of the Shh pathway under conditions of PM2.5 exposure. Our results suggest that the KDM5A's inhibitory regulation on the Shh pathway through the EGR1 gene is a crucial epigenetic mechanism underlying the synaptic dysfunction in hippocampal neurons caused by maternal PM2.5 exposure. This emphasizes the role of epigenetic regulations in neurodevelopmental disorders caused by environmental factors.

Ambient particulate matter exposure induces ferroptosis in hippocampal cells through the GSK3B/Nrf2/GPX4 pathway

Epidemiological studies have established a robust correlation between exposure to ambient particulate matter (PM) and various neurological disorders, with dysregulation of intracellular redox processes and cell death being key mechanisms involved. Ferroptosis, a cell death form characterized by iron-dependent lipid peroxidation and disruption of antioxidant defenses, may be involved in the neurotoxic effects of PM exposure. However, the relationship between PM-induced neurotoxicity and ferroptosis in nerve cells remains to be elucidated. In this study, we utilized a rat model (exposed to PM at a dose of 10 mg/kg body weight per day for 4 weeks) and an HT-22 cell model (exposed to PM at concentrations of 50, 100, and 200 μg/mL for 24 h) to investigate the potential induction of ferroptosis by PM exposure. Furthermore, RNA sequencing analysis was employed to identify hub genes that potentially contribute to the process of ferroptosis, which was subsequently validated through in vivo and in vitro experiments. The results revealed that PM exposure increased MDA content and Fe2+ levels, and decreased SOD activity and GSH/GSSG ratio in rat hippocampal and HT-22 cells. Through RNA sequencing analysis, bioinformatics analysis, and RT-qPCR experiments, we identified GSK3B as a possible hub gene involved in ferroptosis. Subsequent investigations demonstrated that PM exposure increased GSK3B levels and decreased Nrf2, and GPX4 levels in vivo and in vitro. Furthermore, treatment with LY2090314, a specific inhibitor of GSK3B, was found to mitigate the PM-induced elevation of MDA and ROS and restore SOD activity and GSH/GSSG ratio. The LY2090314 treatment promoted the upregulation of Nrf2 and GPX4 and facilitated the nuclear translocation of Nrf2 in HT-22 cells. Moreover, treatment with LY2090314 resulted in the upregulation of Nrf2 and GPX4, along with the facilitation of nuclear translocation of Nrf2. This study suggested that PM-induced ferroptosis in hippocampal cells may be via the GSK3B/Nrf2/GPX4 pathway.

Prenatal air pollution, fetal β-cell dysfunction and neurodevelopmental delay

BACKGROUND

Emerging evidence has reported significant associations of prenatal air pollution exposure with neurodevelopmental delay in offspring. Sensitive exposure windows and the modifiable factor remain elusive.

OBJECTIVE

We aim to identify sensitive windows of air pollution during pregnancy on neurodevelopmental delay, and examine whether cord blood C-peptide mediates the relationship.

METHODS

This study included 7438 mother-newborn pairs in Hefei, China, from 2015 to 2021. Weekly exposure to particulate matter of aerodynamic diameter <2.5 µm, 10 µm (PM2.5, PM10), nitrogen dioxide (NO2) and carbon monoxide (CO) was estimated at regulatory air monitoring stations in Hefei. Denver Developmental Screening Test-II and the Gesell Developmental Schedules were applied to assess the neurodevelopmental delay in children 6-36 mon of age. Distributed lag nonlinear models examined sensitive time windows of prenatal air pollutants exposure. Mediation analysis estimated the mediating role of cord blood C-peptide.

RESULTS

The sensitive PM2.5, PM10, NO2, and CO exposure windows associated with neurodevelopmental delay were throughout pregnancy. Weekly air pollutants exposure was related to higher neurodevelopmental delay risks [cumulative odds ratio (OR): 1.40(1.29,1.53) in PM2.5 (per 10 μg/m3), 1.40(1.28,1.53) in PM10 (per 10 μg/m3), 1.41(1.30,1.52) in CO (per 0.1 mg/m3), and 1.49(1.29,1.72) in NO2 (per 5 μg/m3)]. Mediation analysis indicated 18.3 % contributions of cord C-peptide to the relationship [average mediation effect: 0.04(0.01.0.06); average direct effect: 0.15(0.07.0.25)].

CONCLUSIONS

Exposure to air pollution throughout pregnancy is linked to neurodevelopmental delay mediated by poorer fetal β-cell function. Screening and treatment of abnormal glucose metabolism in infants could benefit the prevention of air pollution-associated neurodevelopment delay.