Air pollution, depressive and anxiety disorders, and brain effects: A systematic review

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.

Sensitive periods for exposure to indoor air pollutants and psychosocial factors in association with symptoms of psychopathology at school-age in a South African birth cohort

Exposure to environmental toxicants and psychosocial stressors during gestation and early life are particularly harmful and may impact brain development. Specifically, exposure to indoor air pollutants (IAP) and psychosocial factors (PF) during these sensitive periods has been shown to predict childhood psychopathology. Here, we investigated sensitive periods for the individual and joint effects of IAP and PF on childhood psychopathology at 6.5 years. We analyzed data from the Drakenstein Child Health Study (N = 599). Exposure to IAP and PF was measured during the second trimester of pregnancy and 4 months postpartum. Childhood psychopathology was assessed at 6.5 years old using the Childhood Behavior Checklist (CBCL). We investigated individual effects of pre- and postnatal exposure to IAP and PF on CBCL scores using adjusted linear regression models, and joint effects of exposures using quantile g-computation and self-organizing maps (SOM). To identify possible sensitive periods, we used a structured life course modeling approach (SLCMA) as well as SOM. Prenatal exposure to IAP or PFs, and the total prenatal mixture assessed using quantile g-computation, were associated with increased psychopathology. SLCMA and SOM models also indicated that the prenatal period is a sensitive period for IAP exposure on childhood psychopathology. Depression and alcohol were associated in both the pre- and postnatal period. In conclusion, pregnancy may be a sensitive period for the effect of IAP on psychopathology. Exposure to maternal depression and alcohol in both periods was also associated with psychopathology. Determining sensitive periods of exposure is vital to ensure effective interventions to reduce psychopathology.

The Power of Lifestyle Psychiatry: A New Approach to Mental Health

The field of psychiatry has evolved over the past 2500 years. Between dynamic psychotherapy and psychopharmacology, lifestyle psychiatry holds a different space. This approach capitalizes on the lifestyle medicine movement, as it promotes change within 6 domains of activity. Apart from incorporating these lifestyle pillars as adjunctive therapy for either psychodynamic therapy or psychotropic medication regimens, lifestyle psychiatry is on the frontier similar to the other growing fields of precision psychiatry, advanced learning in psychiatry, psychedelics in psychiatry, digital mental health, and psychiatric genetics. Any disruption into the historical practice of psychiatry, particularly with the prescription of medications, can be met with scrutiny. We encourage the field of psychiatry to keep an open mind as our field continues to evolve. What makes lifestyle psychiatry particularly powerful and unique in its ability to assess and evaluate internal and external factors that contribute to individual behaviors, and may impact the ability to incorporate healthy lifestyle actions. Internal factors include: emotional regulation, internalized trauma, cognitive factors, and personality traits. On the other hand, external factors include environmental barriers and work-related burnout.

Ambient air pollution and depressed mood in the National Longitudinal Study of Adolescent to Adult Health (Add Health) wave 4

Depression is a major contributor to the global burden of disease. There is limited understanding of how environmental exposures may contribute to depression etiology. We used wave 4 of the National Longitudinal Study of Adolescent to Adult Health (Add Health) to examine associations between low-level ambient air pollution exposure and depressed mood in a generally healthy population of over 10 000 24-32 year olds. Annual mean PM2.5 levels in the 2008-2009 study were close to the current US standard. In fully adjusted quasibinomial logistic regression models, there were no meaningful associations between IQR increases in air pollutant and change in depressed mood status regardless of specific pollutant or moving average lags. In interaction effects models, an IQR increase in lag day 0-30 PM2.5 resulted in 1.20 (95% CI, 1.02-1.41) times higher likelihood of having depressed mood but only for persons with chronic lung disease (interaction P = .04); the association was null for participants without chronic lung disease (OR, 0.98; 95% CI, 0.91-1.05). Our findings suggest that among persons with a lifetime history of chronic lung disease, greater exposure to even low-level PM2.5, PM10, and sulfate may be associated with modest increases in the likelihood of having depressed mood. This article is part of a Special Collection on Environmental Epidemiology.

The impact of particulate matter exposure on global and domain-specific cognitive function: evidence from the Chinese Square Dancer Study

BACKGROUND

There is growing evidence that exposure to particulate matter (PM) is associated with impaired cognitive function. However, limited studies have specifically examined the relationship between PM exposure and domain-specific cognitive function.

METHODS

This study involved 2,668 female participants from the Lifestyle and Healthy Aging of Chinese Square Dancer Study. Global cognitive function was assessed using a composite Z-score derived from four tests: the Auditory Verbal Learning Test (AVLT), Verbal Fluency Test (VFT), Digit Symbol Substitution Test (DSST), and Trail Making Test-B (TMT-B). These tests evaluated specific cognitive subdomains: memory (AVLT), language (VFT), attention (DSST), and executive function (TMT-B). PM concentrations were estimated using a Random Forest (RF) model, which calculated the average concentrations over 1-year and 3-year periods at a high grid resolution of 1 × 1 km. Mixed linear regression was employed to explore the association between PM exposure and cognitive function.

RESULTS

After adjusting for basic socio-demographic factors, a 10 mg/m3 increase in 3-year exposure to PM10 was significantly associated with a decrease in the DSST score by -0.05 (95% confidence interval [CI]: -0.11, 0) and an increase in the TMT-B score by 0.05 (95% CI: 0.01, 0.1). When further adjusting for gaseous pollutants (SO₂, NO₂, and O₃), even stronger associations were observed between 3-year exposure to either PM2.5 or PM10 and performance in both global cognition and specific cognitive subdomains. Specifically, in the DSST subdomain, a 10 µg/m³ increase in 1-year PM10 exposure was associated with a decrease in the score by -0.10 (95% CI: -0.15, -0.04). Age-stratified analyses further indicated that older participants were consistently more vulnerable to PM exposure. Notably, 3-year exposure to both PM2.5 and PM10 was linked to declines in DSST scores across both middle-aged and older age groups.

CONCLUSION

Ambient PM exposure was significantly associated with performance in global cognitive function and specific cognitive domains among Chinese females. Female populations over 65 years old were more susceptible to the adverse effects of PM2.5 and PM10. Among the four subdomains, the DSST showed the strongest association with PM exposure, even at earlier ages, suggesting that impaired attention may serve as an early warning sign of cognitive decline.

CLINICAL TRIAL NUMBER

Not applicable.

Short-term exposure to PM2.5 and high pollution events on depressive symptoms among adolescents

Association between short-term exposure to fine particulate matter (PM2.5) and adolescent depressive symptoms is an under-investigated area and is worthy of further research. Based on a government surveillance data for 195,687 Chinese adolescents, the mixed-effects logistic regression combined with a distributed lag nonlinear model was used to assess the cumulative effect of PM2.5 exposure on depressive symptoms. In addition, high pollution events were defined according to World Health Organization (WHO) air quality guidelines (AQGs) and the Chinese ambient air quality standards, and the associations of increased high pollution events with depressive symptoms and the associated excess risk were estimated. Our results showed that association between short-term exposure to PM2.5 and depressive symptoms was most significant at lag 0 weeks, with each 10 μg/m3 increase in PM2.5 concentration associated with a 3.11 % (95 % CI: 0.70 %, 5.58 %) change in ORs for depressive symptoms. High pollution events were found to contribute to a maximum 3.12 % (95 % CI: 0.52 %, 5.74 %) excess risk of depressive symptoms when defined as 24-hour average PM2.5 concentration exceeding 37.5 μg/m3, WHO AQG interim target 3. Our results highlight the importance of air quality improvement for adolescent depression prevention, and recommend increased psychological support during high pollution events.

Beyond the Smog: Unveiling the Invisible Toll of Air Pollution on the People's Mental Well-Being in Lahore, Pakistan

Background

The manuscript investigates the significant detrimental impact of air pollution, particularly smog, on the mental health of residents in Lahore, Pakistan. Research highlights various ways in which pollutants contribute to mental health issues, including increased risks of depression and anxiety, and direct impacts on cognitive function.

Aims

This study aims to establish a link between air quality and its psychological impact on the inhabitants of Lahore. It seeks to advocate for effective interventions to mitigate the adverse effects of air pollution on mental health.

Methods

This study examined existing literature on the Internet to understand the link between air pollution and mental health. This manuscript aimed to provide a foundation for developing evidence-based solutions within the current healthcare landscape.

Results

Searching for "smog," "mental health," and "air pollution" yielded these results, a strong association between increasing levels of air pollution in Lahore and its impact on residents' mental well-being. Despite ongoing efforts to mitigate air pollution, the persistent smog burden in Lahore highlights the need for more effective and decisive interventions to improve air quality and safeguard the population's mental health.

Conclusion

This study serves as a preliminary investigation into the intricate relationship between air pollution and mental health. It emphasizes the need for further research to comprehensively understand this critical issue and proper policy implications and potential interventions are required to mitigate the adverse effects of air pollution on mental health.

Association of ambient air pollution exposure with psychological distress in mid and later adulthood: A 26-year prospective cohort study

BACKGROUND

Existing evidence on associations between exposure to air pollution and psychological distress from middle to older age is limited by consideration of short exposure periods, poor historical covariates, exposures and outcomes, and cross-sectional study designs. We aimed to examine this association over a 26-year period between ages 43 and 69.

METHODS

We utilised data from the Medical Research Council National Survey of Health and Development Study (the 1946 British birth cohort). Land-use regression models estimated exposure to specific air pollutants using household addresses for 1991 (NO2), 2001 (PM10, NO2), and 2010 (NO2, NOx, PM10, PM2.5, PMcoarse, PM2.5abs). These were linked to the closest data collection wave at ages 43, 53 and 60-64, respectively. Psychological distress was assessed through the 28-item version of the General Health Questionnaire (GHQ-28), at ages 53, 60-64 and 69. Associations between each of the pollutants with psychological distress were analysed using generalised linear mixed models, adjusted for pollution exposure before age 43, assigned sex, social class, smoking status, neighbourhood deprivation, and previous mental health problems. We also examined effect modification by social class.

RESULTS

At age 69, 2125 participants completed the GHQ-28. In fully adjusted models, higher NO2 exposure was associated with higher GHQ-28 scores across a 26-year period (β=0.023, 95%CI:0.005, 0.040 per interquartile range increase in exposure), whereas higher exposure to PM10 was associated with lower GHQ-28 scores across a 16-year period (β=-0.021, 95%CI:-0.037, -0.006). There was no evidence of associations between exposure to other pollutants at age 60-64 and GHQ-28 at age 69. We found no effect modification by social class.

CONCLUSIONS

In this cohort there was some evidence of an association between higher cumulative exposure to NO2 and higher psychological distress, but mixed associations with other exposures. Policies to reduce pollutant exposure may help improve psychological symptoms in middle to late adulthood.

Rethinking Depression-Beyond Neurotransmitters: An Integrated Psychoneuroendocrineimmunology Framework for Depression's Pathophysiology and Tailored Treatment

It is known that the effectiveness of drug treatment for depression, ammine deficit based, is largely unsatisfactory. In this review, we examine the proposal of a precision therapy has emerged and has received a strong push by the identification of the role of inflammation in depression. However, precision psychiatry risks being caught in the reductionist trap of searching for the molecular switch that resets the whole system and switches off the disease. This is an illusion since the human being is complex and depression is a systemic and variable disorder. In this study, we show the inadequacy of the reductionist paradigm, and, at the same time, illustrate the superiority of the systemic paradigm centered on psychoneuroendocrineimmunology (PNEI). According to the PNEI paradigm, depression is a disease of the whole human being, caused by different sources working together: psychological, biological, and behavioral. This means knowing the biological and psychological history of the subject, identifying relational and biological crisis factors, and building personalized treatments targeting those factors with the tools of medicine and psychology, which are not reducible to the combination of drugs and psychotherapy. Our proposal presents a paradigm shift that is both theoretical and practical, which enables clinicians to assess patients experiencing depression in a unified way and treat them in an integrated manner.

The evolving neurobiology of early-life stress

Because early-life stress is common and constitutes a strong risk factor for cognitive and mental health disorders, it has been the focus of a multitude of studies in humans and experimental models. Yet, we have an incomplete understanding of what is perceived as stressful by the developing brain, what aspects of stress influence brain maturation, what developmental ages are particularly vulnerable to stress, which molecules mediate the effects of stress on brain operations, and how transient stressful experiences can lead to enduring emotional and cognitive dysfunctions. Here, we discuss these themes, highlight the challenges and progress in resolving them, and propose new concepts and avenues for future research.

Coming to terms with climate change: a glossary for climate change impacts on mental health and well-being

Climate change is a major threat to global health. Its effects on physical health are increasingly recognised, but mental health impacts have received less attention. The mental health effects of climate change can be direct (resulting from personal exposure to acute and chronic climatic changes), indirect (via the impact on various socioeconomic, political and environmental determinants of mental health) and overarching (via knowledge, education and awareness of climate change). These impacts are unequally distributed according to long-standing structural inequities which are exacerbated by climate change. We outline key concepts and pathways through which climate change may affect mental health and explore the responses to climate change at different levels, from emotions to politics, to highlight the need for multilevel action. We provide a broad reference to help guide researchers, practitioners and policy-makers in the use and understanding of different terms in this rapidly growing interdisciplinary field.

A systematic review of air pollution exposure and brain structure and function during development

OBJECTIVES

Air pollutants are known neurotoxicants. In this updated systematic review, we evaluate new evidence since our 2019 systematic review on the effect of outdoor air pollution exposure on childhood and adolescent brain structure and function as measured by magnetic resonance imaging (MRI).

METHODS

Using PubMed, Web of Science, and Scopus we conducted an updated literature search and systematic review of articles published through January 2025, using key terms for air pollution and functional and/or structural MRI. Two raters independently screened all articles using Covidence and implemented the risk of bias instrument for systematic reviews used to inform the World Health Organization Global Air Quality Guidelines.

RESULTS

We identified 29 relevant papers, and 20 new studies met our inclusion criteria. Including six studies from our 2019 review, the 26 publications to date include study populations from the United States, Netherlands, Spain, and United Kingdom. Studies investigated exposure periods spanning pregnancy through early adolescence, and estimated air pollutant exposure levels via personal monitoring, geospatial residential estimates, or school courtyard monitors. Brain MRI occurred when children were on average 6-14.7 years old; however, one study assessed newborns. Several MRI modalities were leveraged, including structural morphology, diffusion tensor imaging, restriction spectrum imaging, arterial spin labeling, magnetic resonance spectroscopy, as well as resting-state and task-based functional MRI. Air pollutants were associated with widespread brain differences, although the magnitude and direction of findings are largely inconsistent, making it difficult to draw strong conclusions.

CONCLUSION

Prenatal and childhood exposure to outdoor air pollution is associated with structural and functional brain variations. Compared to our initial 2019 review comprised of only cross-sectional studies, the current literature now includes longitudinal studies and more advanced neuroimaging methods. Further research is needed to clarify the effects of developmental timing, along with the downstream implications of outdoor air pollution exposure on children's cognitive and mental health.

Neurodevelopment and climate change

OBJECTIVE

This article aims to assess the impact of climate change, a reality already present on the neurodevelopment of both neurotypical and atypical children.

DATA SOURCES

A narrative review of the literature was carried out based on articles available in the PubMed database, published in the last five years using the keywords neurodevelopment and climate change, as well as websites of organizations dedicated to childhood such as UNICEF, the American Academy of Pediatrics and the Center for Developing Childhood at Harvard University.

SUMMARY OF FINDINGS

Children and adolescents are more directly affected by the effects of climate change due to their developmental stage and greater vulnerability. Prolonged exposure to air pollutants can affect brain development, resulting in cognitive and behavioral problems. Extreme weather events, such as floods, cyclones, and heat waves, can destroy essential infrastructure such as schools and hospitals, interrupting the educational process and access to health care. Changes in rainfall patterns and extreme droughts can affect food production, leading to malnutrition and food insecurity. Direct experience of natural disasters can cause stress and psychological trauma, affecting children's emotional and mental well-being.

CONCLUSIONS

Studies clearly demonstrate the potential impact of climate change on the neurodevelopment and mental health of children and adolescents. This topic should be part of the current agenda of pediatricians, not only treating the resulting illnesses but mainly acting on the front line and supporting proposals to attenuate the environmental disaster that has already occurred.

Durational effect of ambient air pollution on hospital admissions of schizophrenia: a time series analysis

BACKGROUND

Schizophrenia may be exacerbated by ambient air pollution. In this study, we aim to explore the association of air pollution with hospital admission for schizophrenia in Liuzhou, China.

METHODS

The daily concentration of air pollutants was gathered from an average of seven fixed monitoring sites in Liuzhou, while the daily admission data for schizophrenia was received from The Guangxi Zhuang Autonomous Region Brain Hospital. A Poisson generalized linear regression model in conjunction with a distributed lag nonlinear model was utilized to quantify the exposure-lag-response connection between ambient air pollution and schizophrenia hospitalization. The stratification analysis was then carried out by age, gender, and season.

RESULTS

PM2.5, PM10, and SO2 was significantly associated with elevated number of schizophrenia hospitalization. We observed the largest single-day effects of PM2.5 at lag 17 day, PM10 at lag 17 day, and SO2 at lag 28 day, with the corresponding RRs being 1.01611 (95% CI:1.00652-1.02579), 1.01648 (95% CI:1.00603-1.02704), and 1.02001 (95% CI: 1.00001-1.04041), respectively. Stratification analysis revealed that patients who were < 45 years old and female were more vulnerable to hospitalization due to exposure to PM2.5 and PM10. The effects of PM2.5 and PM10 were more noticeable during the cooler seasons than during the warmer one.

CONCLUSIONS

This study reveals that being exposed to PM2.5, PM10, and SO2 may increase the chance of schizophrenia hospitalization.

Associations between residential segregation, ambient air pollution, and hippocampal features in recent trauma survivors

Background

Residential segregation is associated with differential exposure to air pollution. Hippocampus structure and function are highly susceptible to pollutants and associated with posttraumatic stress disorder (PTSD) development. Therefore, we investigated associations between residential segregation, air pollutants, hippocampal neurobiology, and PTSD in recent trauma survivors.

Methods

Participants (N = 278; 34% non-Hispanic white, 46% Non-Hispanic Black, 16% Hispanic) completed multimodal neuroimaging two weeks after trauma. Yearly averages of air pollutants (PM2.5 and NO2) and racial/economic segregation (Index of Concentration at the Extremes) were derived from each participant's address. Linear models assessed if air pollutants mediated associations between segregation and hippocampal volume, threat reactivity, or parahippocampal cingulum fractional anisotropy (FA) after covarying for age, sex, income, and 2-week PTSD symptoms. Further models evaluated if pollutants or segregation prospectively predicted PTSD symptoms six months post-trauma.

Results

Non-Hispanic Black participants lived in neighborhoods with significantly greater segregation and air pollution compared to Hispanic and non-Hispanic white participants (ps<.001). There was a significant indirect effect of NO2 between segregation and FA values (β = 0.08, 95% CI[0.01, 0.15]), and an indirect effect of PM2.5 between segregation and threat reactivity (β = -0.08, 95% CI[-0.14, -0.01]). There was no direct effect of segregation on hippocampal features. Pollutants and segregation were not associated with PTSD symptoms .

Conclusion

Residential segregation is associated with greater air pollution exposure, which is in turn associated with variability in hippocampal features among recent trauma survivors. Further research is needed to assess relationships between other environmental factors and trauma and stress-related disorders.

Psychological repercussions of PM air pollution in human aging: a comprehensive review of urban and rural environments

Air pollution and its effects on population health are currently among the most important public health issues. It is well established that the impact of air pollution on health is exceedingly high, although it ignores its real scope and effects on the aging process because studies on air quality have largely focused on younger age groups. Herein, we emphasize the relevance of air quality to the behavioral aging process, taking into account the place of residence - rural or urban. We raise the following question: Can air quality and residential settings modulate cognitive, emotional and social behaviors during the aging? Some studies have analyzed the role of residential settings and air pollution in the context of a behavioral frame in elderly people. Based on the analyzed literature, this revision concluded that air pollutants affect cognitive function, increasing the risk of dementia as well as depression and anxiety emotional responses. In addition, social networks and inclusion can modulate and mitigate the effects observed during the aging in rural areas that are exposed to less contamination. Although there is no consensus, it seems that some observed behavioral effects are sex-dependent, as women are more vulnerable to air pollution. Additionally, we examined why older adults are vulnerable to the health effects of Particulate Matter (PM) exposure and highlighted the importance of social health in this context. Environmental agents could be the key to understanding the susceptibility and variability observed during aging in behavioral symptoms. Although cognitive decline is related to increased age, it is not a manipulated factor. Efforts should be centered on locating factors implicated in the aging process that could be susceptible to manipulation or variation, such as the choice of the place of residence and the air that we are breathing. Given the significant societal impact of PM, research and policy regulations should be closely aligned and collaborative.

Sleep duration and efficiency moderate the effects of prenatal and childhood ambient pollutant exposure on global white matter microstructural integrity in adolescence

Background

Air pollution is a ubiquitous neurotoxicant associated with alterations in structural connectivity. Good habitual sleep may be an important protective lifestyle factor due to its involvement in the brain waste clearance and its bidirectional relationship with immune function. Wearable multisensory devices may provide more objective measures of sleep quantity and quality. We investigated whether sleep duration and efficiency moderated the relationship between prenatal and childhood pollutant exposure and whole-brain white matter microstructural integrity at ages 10-13 years.

Methods

We used multi-shell diffusion-weighted imaging data collected on 3T MRI scanners and objective sleep data collected with Fitbit Charge 2 from the 2-year follow-up visit for 2178 subjects in the Adolescent Brain Cognitive Development Study®. White matter tracts were identified using a probabilistic atlas. Restriction spectrum imaging was performed to extract restricted normalized isotropic (RNI) and directional (RND) signal fraction parameters for all white matter tracts, then averaged to calculate global measures. Sleep duration was calculated by summing the time spent in each sleep stage; sleep efficiency was calculated by dividing sleep duration by time spent in bed. Using an ensemble-based modeling approach, air pollution concentrations of PM2.5, NO2, and O3 were assigned to each child's residential addresses during the prenatal period (9-month average before birthdate) as well as at ages 9-10 years. Multi-pollutant linear mixed effects models assessed the associations between global RNI and RND and sleep-by-pollutant interactions, adjusting for appropriate covariates.

Results

Sleep duration interacted with childhood NO2 exposure and sleep efficiency interacted with prenatal O3 exposure to affect RND at ages 10-13 years. Longer sleep duration and higher sleep efficiency in the context of higher pollutant exposure was associated with lower RND compared to those with similar pollutant exposure but shorter sleep duration and lower sleep efficiency.

Conclusions

Low-level air pollution poses a risk to brain health in youth, and healthy sleep duration and efficiency may increase resilience to its harmful effects on white matter microstructural integrity. Future studies should evaluate the generalizability of these results in more diverse cohorts as well as utilize longitudinal data to understand how sleep may impact brain health trajectories in the context of pollution over time.

Large-scale georeferenced neuroimaging and psychometry data link the urban environmental exposome with brain health

In face of cumulating evidence about the impact of human-induced environmental changes on mental health and behavior, our understanding of the main effects and interactions between environmental factors - i.e., the exposome and the brain - is still limited. We seek to fill this knowledge gap by leveraging georeferenced large-scale brain imaging and psychometry data from the adult community-dwelling population (n = 2672; mean age 63 ± 10 years). For monitoring brain anatomy, we extract morphometry features from a nested subset of the cohort (n = 944) with magnetic resonance imaging. Using an iterative analytical strategy testing the moderator role of geospatially encoded exposome factors on the association between brain anatomy and psychometry, we demonstrate that individuals' anxiety state and psychosocial functioning are among the mental health characteristics showing associations with the urban exposome. The clusters of higher anxiety state and lower current psychosocial functioning coincide spatially with a lower vegetation density and higher air pollution. The univariate multiscale geographically weighted regression identifies the spatial scale of associations between individuals' levels of anxiety state, psychosocial functioning, and overall cognition with vegetation density, air pollution and structures of the limbic network. Moreover, the multiscale geographically weighted regression interaction model reveals spatially confined exposome features with moderating effect on the brain-psychometry/cognitive performance relationships. Our original findings testing the role of exposome factors on brain and behavior at the individual level, underscore the role of environmental and spatial context in moderating brain-behavior dynamics across the adult lifespan.

Investigating associations between the physical living environment and hippocampus in adulthood and older age

It is by now well known that the physical living environment has a major impact on people's life, but the neural structures involved in this relationship remain to be explored. Most studies investigating this relationship only focus on single environmental predictors. In order to understand how the multitude of factors constituting the living environment relate to brain structure we used data from the UK Biobank (n = 21,094; age Mean = 63.35 years; SD = 7.46; range = 45-82) to examine how individuals' immediate characteristics around the home address (e.g., green space; air pollution in the neighborhood) are associated with hippocampal volume, a brain region known to be highly plastic. We accounted for common demographic factors that have been shown to be associated with brain structure and known factors such as sex, income, education, and age. We made use of an analytical paradigm based on the feature importance estimation and recursive feature elimination with decision tree ensembles as well as linear regression analysis. Results identified a subset of environmental measures (e.g., pollution, green space, noise) most strongly associated with hippocampal volume across adulthood. Findings highlight the importance of the environment for individuals' brain structure.

Living and neighborhood environments and anxiety symptoms among older adults in Anhui, China: evidence from a cross-sectional study

OBJECTIVE

This study aims to investigate the relationships between living and neighborhood environmental factors and anxiety symptoms among older adults residing in urban and rural areas of Anhui Province, China.

METHODS

Data were collected from 5876 participants in a cross-sectional study carried out in four cities located in Anhui, China. Anxiety symptoms were evaluated via the Generalized Anxiety Disorder scale (GAD-7), and participants with scores of 5 and above were defined as having anxiety symptoms. The presence of dust and noise in the context of daily life was used to evaluate the living environment of the participants. The neighborhood environment was assessed by the availability of barrier-free facilities, proximity to facilities (supermarkets, restaurants, hospitals, and parks), and green and blue space near participants' dwellings. Multilevel linear and logistic regression analyses were used to estimate the associations between these environmental factors and anxiety symptoms.

RESULTS

The participants who lived in dusty environments had elevated GAD-7 scores and higher odds of anxiety (dust: β = 0.754, 95% CI: 0.337, 1.171; OR = 1.451, 95% CI: 1.164, 1.809). Having barrier-free facilities and the existence of a neighboring park decreased the GAD-7 scores and the likelihood of having anxiety symptoms (barrier-free facilities: β=-0.503, 95% CI: -0.992, -0.085; OR = 0.768, 95% CI: 0.656, 0.899; park: β=-0.478, 95% CI: -0.830, -0.125; OR = 0.599, 95% CI: 0.440, 0.816). However, participants residing in close proximity to the hospital presented an increased likelihood of experiencing anxiety symptoms (OR = 1.377, 95% CI: 1.162, 1.631).

CONCLUSIONS

Participants who lived in dusty and noisy environments were more likely to suffer from anxiety, whereas those who lived near barrier-free facilities and parks were at lower risk. The findings emphasize the need for targeted interventions to create age-friendly communities, suggesting an integrated approach that combines environmental health strategies with mental health strategies for older adults.

EnvironMental Health: A Framework for an Emerging Field at the Intersection of the Environment and Mental Health Crises

Understanding how the environment shapes our mental and cognitive health is imperative to support efforts that promote healthy and sustainable living conditions. The etiology of mental health conditions remains often unclear, and social factors have received more scrutiny than natural or built environments. We present a conceptual framework illustrating the emerging intersection between the environment and neuropsychological health, intended to structure and guide research and funding, as well as public health and environmental initiatives. We conducted a scoping review of reviews of existing evidence on the impacts of the environment on mental and cognitive health. We found that an extensive body of work was focused on chemical hazards and the built environment and their associations with neurological and mental health, including attention-deficit/hyperactivity disorder (ADHD), autism, dementia, and mood. We identified emerging areas of research intersecting environmental factors such as air, water, light, and green space with schizophrenia and behavioral health. Our analysis of the intersections between the environment and mental and cognitive health allows for the identification of knowledge clusters and gaps, contextualizing needs and opportunities for future research and funding strategies. These significant connections showcase the importance of understanding the relationships between the environment and mental and cognitive health. With this work, we assert that the protection of the environment and its integration into healthcare can bring cascading benefits and synergies to mental and cognitive health and well-being and address the social and economic burden of the mental health crises.

Contributing Factors to the Rise in Adolescent Anxiety and Associated Mental Health Disorders: A Narrative Review of Current Literature

BACKGROUND

The prevalence of anxiety among adolescents has seen a notable increase in recent years, becoming a significant public health concern. In fact, anxiety is substantially more prevalent in Generation Z (individuals born between 1997 and 2012) than in any of the past three generations. We aimed to examine what factors contribute to the increased prevalence in teen anxiety and identify points of intervention.

METHODS

This study employed a narrative review method. We performed a literature search of the PubMed, ScienceDirect, and Medline databases and identified original research and review articles discussing increased anxiety and other mental health disorders in Generation Z.

RESULTS

We provide a comprehensive overview of the factors contributing to the increased rates of adolescent anxiety, including academic pressures, social media influence, family dynamics, and broader societal stressors.

CONCLUSIONS

In this narrative review, we examine the multifaceted nature of adolescent anxiety, identifying contributing factors. Additionally, we discuss potential clinical, educational, and community-based interventions to prevent and treat adolescent anxiety. By understanding and addressing the underlying causes of anxiety, it is possible to mitigate its impact and promote healthier developmental trajectories for young individuals.

An ex vivo model of systemically-mediated effects of ozone inhalation on the brain

Air pollution is associated with increased risk of neurodegenerative and neuropsychiatric conditions. While animal models have increased our understanding of how air pollution contributes to brain pathologies - including through oxidative stress, inflammatory, and stress hormone pathways - investigation of underlying mechanisms remains limited due to a lack of human-relevant models that incorporate systemic processes. Our objective was to establish an ex vivo approach that enables assessment of the roles of plasma mediators in pollutant-induced effects in the brain. As a proof-of-concept for application in the human context, we assessed whether such effects reproduced in vivo responses to pollutant exposure. Primary rat hippocampal neurons and microglia were each treated with plasma collected from rats immediately or 24 h after ozone inhalation (0 or 0.8 ppm) ± pre-treatment with the glucocorticoid synthesis inhibitor metyrapone. Microglia were further challenged with lipopolysaccharide to evaluate modification of inflammatory responses. Plasma from the ozone-exposed group produced transcriptional changes (inflammatory, antioxidant, glucocorticoid-responsive) in neurons, some of which were glucocorticoid-dependent. Ex vivo and hippocampal responses were strongly correlated, establishing the in vivo relevance of the model. Plasma from the ozone-exposed group modified inflammatory responses to lipopolysaccharide challenge in microglia, demonstrating the model's utility to assess functional changes resulting from pollutant exposure. This study establishes that an ex vivo approach can reproduce ozone-induced effects in the brain. The model was sensitive to specific plasma mediators and temporal effects, and enabled assessment of functional responses. This approach may serve to investigate mechanisms underlying effects of pollutants on the human brain.

Study on the relationship between indoor ventilation frequency and anxiety and depression symptoms in older persons: based on the data of 2018 CLHLS

BACKGROUND

To investigate the association between indoor ventilation frequency and symptoms of depression and anxiety in older persons.

METHODS

A binary logistic regression model was used to analyze the effects of indoor ventilation frequency on depression and anxiety by using data from the 2018 Chinese longitudinal healthy longevity survey (CLHLS).

RESULTS

A total of 9,690 older persons with an average age of (83.20 ± 11.27) years were included, including 4,458 males (46.0%) and 5,232 females (54.0%). The average score of indoor ventilation frequency was (6.06 ± 1.98) points, including 770 people (7.9%) with low frequency, 3,066 people (31.6%) with medium frequency, and 5,854 people (60.4%) with high frequency. 842 (8.7%) had symptoms of depression and 204 (2.1%) had symptoms of anxiety. Compared with the older persons with low indoor ventilation frequency, the older persons with higher ventilation frequency had a lower incidence of depression (OR(95%CI) = 1.92 (1.50 ∼ 2.46), 1.51 (1.27 ∼ 1.79); P < 0.001). However indoor ventilation frequency was not associated with anxiety symptoms.

CONCLUSION

Indoor ventilation frequency is related to depressive symptoms in older persons. Communities and families should pay more attention to indoor ventilation and intervene in time to promote and improve the mental health of older persons.

Impact of air pollution on depressive symptoms and the modifying role of physical activity: Evidence from the CHARLS study

The association between air pollution and depressive symptoms has not been thoroughly investigated, and the role of physical activity (PA) is particularly unclear. Although PA has been shown to alleviate depression, it may also increase exposure to air pollution, potentially exacerbating its adverse effects. A total of 17,332 participants aged 45 years and older from the 2018 wave of the China Health and Retirement Longitudinal Study (CHARLS) were included in this study to assess the causal effect of air pollution on depressive symptoms in China and to clarify the role of PA in this relationship. Depressive symptoms were assessed using the Center for Epidemiological Studies Depression Scale (CES-D). Data on particulate matter (PM1, PM2.5, and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO) were obtained from the ChinaHighAirPollutants (CHAP) dataset. PA levels were measured using a standardized questionnaire and categorized as low or high. An instrumental variable (IV) approach was used to estimate the causal effect of air pollution on depressive symptoms. Potential effect modification by PA was assessed. The IV estimates showed that all air pollutants were significantly and adversely associated with depressive symptoms, with a per interquartile range (IQR) increase in PM1, PM2.5, PM10, NO2, SO2, O3, and CO associated with 1.57 (95% confidence interval (CI): 1.15, 1.99), 1.49 (95% CI: 1.10, 1.89), 1.71 (95% CI: 1.26, 2.17), 2.22 (95% CI: 1.62, 2.81), 1.30 (95% CI: 0.96, 1.65), 4.67 (95% CI: 3.37, 5.98), and 0.97 (95% CI: 0.71, 1.22) units increase in CES-D scores, respectively. PA significantly modified this association, with higher PA levels mitigating the adverse effects of air pollution on depressive symptoms.

The impact of long-term exposure to NO2, O3, and their oxidative potential on adolescents' mental health, and the protective role of school-based greenness

Recent increases in nitrogen dioxide (NO2) and ozone (O3), two highly reactive and oxidative pollutants, have raised concerns about their potential impact on adolescent mental health. This study leveraged data from the Chinese National Survey on Students' Constitution and Health (CNSSCH) in 2019, a nationally representative cross-sectional survey of Chinese adolescents. A total of 149,697 adolescents aged 10-18 years were included in this study. NO2 and O3 were sourced from the ChinaHighAirPollutants dataset, and the combined oxidative potential (OX) was subsequently calculated using the concentrations of NO2 and O3. The study quantitively examined the association of NO2, O3, and OX with adolescent mental health using the Dual Factor Model of Mental Health (DFM), which was derived from a questionnaire. According to the DFM, mental health status was divided into four groups: complete mental health, vulnerable, symptomatic but content, and troubled. Greenness around schools, measured by the Normalized Difference Vegetation Index (NDVI), was examined for its potential effect modification on the association between NO2, O3, OX, and mental health. Each IQR (Interquartile Range) increase in OX was related to adverse mental health outcomes, with ORs of 1.17 (95 % CI: 1.06, 1.29) for being vulnerable, 1.20 (95 % CI: 1.12, 1.28) for being more symptomatic but content, and 1.15 (95 % CI: 1.07, 1.23) for being troubled. Similar findings emerged in relation to O3 exposure. A positive association was observed between NO2 exposure and being vulnerable (OR = 1.07; 95 % CI: 1.01, 1.16). Additionally, the impact of exposure to NO2, O3, and OX on mental health outcomes was significantly stronger in the low-level NDVI group compared to the high-level NDVI group (P for interaction < 0.05). The joint effects analysis revealed that adolescents exposed to high levels of air pollutants and low NDVI had the highest odds of adverse mental health outcomes. These results highlight the complex relationship between NO2, O3, OX, and mental health, with particular emphasis on the underexplored role of OX. Notably, the findings suggest that reducing pollution and increasing greenery could offer significant benefits for improving adolescent mental health.

Examining associations of air pollution and green space with depressive symptoms in adults: A LongITools cross-cohort analysis

OBJECTIVES

Evidence suggests that high levels of air pollution and less green space increase depressive symptoms in adults. However, results are mixed and cross-cohort comparisons are scarce, largely due to heterogeneity in exposure assessment. Also, the impact of these exposures on the trajectory of depressive symptoms over time has been less studied. We investigated the association of air pollution and green space with depressive symptoms in adulthood and whether these exposures modify the trajectory of depressive symptoms leveraging harmonized data from four population-based cohorts across the Netherlands and United Kingdom (UK).

METHODS

We analyzed data from the Dutch Famine Birth Cohort (DFBC) (n = 840, baseline ages: 56-61), and the Rotterdam Study (RS) (RS-I n = 4,049, baseline ages: 61-101 and RS-II n = 2,861, baseline ages: 55-99), in the Netherlands, and the Avon Longitudinal Study of Parents and Children (ALSPAC) (n = 17,100, baseline ages: 18-71) in the UK, each using a different validated instrument for depressive symptoms, with 3-11 repeated measures. European-wide environmental data was linked to participants' addresses at baseline. Linear mixed-models were used to estimate associations of air pollution and green space with standardized cohort-specific depressive symptoms, and whether these exposures modify the trajectory of depressive symptoms.

RESULTS

Long-term exposure to fine particulate matter (PM2.5) was positively associated with overall higher standardized depressive symptom scores in ALSPAC and RS-I (β per 10 μg/m3 increase in PM2.5: 0.07 SD, 95%CI 0.02, 0.11 and 0.13 SD, 95%CI 0.02, 0.24, respectively). Exposure to higher normalized difference vegetation index (NDVI) at 300 m buffer was associated with lower depressive symptoms in DFBC (β per 0.1 increase in NDVI: 0.08, 95%CI -0.14, -0.01). In RS-II, the positive effect of higher NDVI at 300-m buffer on depressive symptoms decreased over time, but this effect was very small (β per 0.1 increase in NDVI: 0.01 SD per year, 95%CI 0.00, 0.01).

CONCLUSION

Air pollution in the form of particulate matter as well as green space were associated with depressive symptoms across multiple cohorts. In the majority of cohorts, depressive symptoms increased with age, but we found little evidence that trajectories of depressive symptoms are influenced by exposure to environmental variables.

Environmental regulation and mental well-being: Evidence from China's air pollution prevention and control action plan

This study investigates how enhanced environmental regulation can improve individuals' mental well-being, focusing on the impact of China's so far most stringent air pollution control policy, the 2013 Air Pollution Prevention and Control Action Plan (APPCAP). Exploiting variations in timing and regions of the implementation of the policy, we find that the APPCAP has significantly improved people's mental well-being. We test several potential socio-economic channels including reduced air pollution, enhanced environmental awareness, improved physical health, and decreased physical activities during periods of heavy pollution, through which environmental regulation may affect mental well-being. Our findings highlight that increased public awareness concerning air pollution plays an important role in the health effects of environmental regulations. The positive effects of environmental regulation on mental well-being are particularly pronounced among individuals aged 45-59 and for those with higher-than-average income or education. We do not find that the positive effects of environmental regulation differ by gender. We further show that the 4-week prevalence of mental/neurological disease dropped significantly, by about 0.38 percentage points, after the implementation of the APPCAP, reaffirming significant mental health benefits from the environmental regulation.

Nature-based solutions to address anxiety disorders: A cross-sectional ecological study of green spatial patterns in Taiwan

Air pollution and heat increase the prevalence and risk of anxiety disorders, which are particularly severe under the increasing trends of climate change and urbanization. Well-designed green spaces have mediating effects on the threats posed by environmental deterioration and promote public health. However, previous research has overlooked these effects. This cross-sectional ecological study applied partial least squares structural equation modeling to data from Taiwanese cities and towns to infer the vital influences of and complex relationships among green spatial patterns (i.e., the dispersion, patch area, fragmentation, aggregation, and coverage ratio of green spaces), socioeconomic status (i.e., income and population aging), atmospheric environment (i.e., air pollution and high temperature), and anxiety disorders. The results reveal that minimizing the dispersion of green spaces and maximizing their patch area and coverage ratio are associated with reduced prevalence of anxiety disorders. Air pollution and high temperature mediate the influence of green spatial patterns on anxiety disorders. Population aging, air pollution, and high temperature are factors that increase the prevalence rate of anxiety disorders, whereas income level has a negative effect. This study identified the pathways and influences (i.e., indirect, direct, and total impacts) of green spatial pattern characteristics on anxiety disorders. These findings show that the adoption of effective greening policies may promote the development of healthy cities. Moreover, this study provides a useful methodology for clarifying complex pathways and identifying vital factors that can be applied to future research in health science and policy.

Particulate matter exposure and its consequences on hippocampal neurogenesis and cognitive function in experimental models

Exposure to air pollution is thought to cause millions of deaths globally each year. According to the Who 2018, approximately 7 million deaths annually are caused predominantly by noncommunicable diseases due to air pollution. Exposure to air particulate matter 2.5 (PM2.5) has been strongly associated with increased mortality and has significant effects on brain health. Air pollution, particularly ultrafine particulate matter, has emerged as a serious environmental concern with profound implications for human health. Studies in animal models have indicated that exposure to these pollutants during gestational development impacts prenatal and postnatal brain development. In particular, air pollution has been increasingly identified as a potential causative factor, as it affects neurogenesis in the brain's hippocampal region. The hippocampus is highly vulnerable to PM exposure, and any alteration in the structure or function of this region leads to various neurodevelopmental defects and neurodegenerative disorders via oxidative stress, microglial activation, neuronal death, and differential expression of genes. The neurogenesis process involves several steps, such as proliferation, differentiation, migration, synaptogenesis, and neuritogenesis. If any step of the neurogenesis process is hampered by environmental exposure or other factors, it can lead to neurodevelopmental defects, neurodegenerative disorders, and cognitive decline. One significant contributor to these alterations is air pollution, which ranks as the leading environmental risk factor worldwide. Some of the most common effects include oxidative stress, neuroinflammation, depressive behavior, altered cognitive processes, and microglial activation. This review explores how prenatal and postnatal PM exposure affects the hippocampal regions of the brain and the defects associated with exposure.

Sufficient sleep and physical activity can relieve the effects of long-term exposure to particulate matter on depressive symptoms among 0.31 million children and adolescents from 103 counties in China

BACKGROUND

Although long-term exposures to air pollutants have been linked to mental disorders, existing studies remain limited and inconsistent. We investigated the relationship between exposure to particulate matter (PM) and depressive symptoms, as well as the potential role of sleep duration and physical activity.

METHOD

Using the surveillance data (2019 to 2022) of common diseases and risk factors among 312,390 students aged 10-25 years, logistic regression, generalized liner model (GLM) and restricted cubic spline (RCS) were employed to investigate the relationship between long-term exposure to PM and depressive symptoms.

RESULT

Significant associations were found between PM1 (OR = 1.21, 95 % CI: 1.12-1.32), PM2.5 (OR = 1.24, 95 % CI: 1.19-1.38), and PM10 (OR = 1.87, 95 % CI: 1.69-2.07) and increased risks of depressive symptoms. Sleep duration and physical activity relieved these associations. The odds ratios (ORs) of PM1, PM2.5, and PM10 on depressive symptoms were lower in group with sufficient sleep (1.02 vs. 1.49, 1.20 vs. 1.80, 2.15 vs. 2.23), lower in group with high level MVPA (1.13 vs. 1.48, 1.14 vs. 1.58, 1.85 vs. 2.38), and lower in group with high level outdoor activity (1.19 vs. 1.55, 1.23 vs. 1.63, 1.83 vs. 2.72).

LIMITATIONS

Conclusions about causality remain speculative because of the cross-sectional design.

CONCLUSION

Sufficient sleep duration and outdoor activity may mitigate the decline in mental health among adults in developing countries caused by long-term exposure to PM. This contribution enhanced our understanding of the mechanisms linking air pollution to mental health.

Mental health amid climate crisis: A narrative review

The global community is currently facing a pressing challenge posed by climate change, which is profoundly impacting both human life and biodiversity. This encompasses issues such as rising global temperatures, heightened sea levels, amplified ultraviolet radiation exposure, more frequent and intense natural calamities, and the subsequent health risks. Additionally, mental health is also being impacted by these environmental changes. This review thoroughly examines the mental health consequences of climate change in various settings and among vulnerable populations, with a particular emphasis on India.

Mechanistic insights regarding neuropsychiatric and neuropathologic impacts of air pollution

Air pollution is a significant environmental health risk for urban areas and developing countries. Air pollution may contribute to the incidence of cardiopulmonary and metabolic diseases. Evidence also points to the role of air pollution in worsening or developing neurological and neuropsychiatric conditions. Inhaled pollutants include compositionally differing mixtures of respirable gaseous and particulate components of varied sizes, solubilities, and chemistry. Inhalation of combustibles and volatile organic compounds (VOCs) or other irritant particulate matter (PM) may trigger lung sensory afferents which initiate a sympathetic stress response via activation of the hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal-medullary (SAM) axes. Activation of SAM and HPA axes are associated with selective inhibition of hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-thyroid (HPT) axes following exposure. Regarding chronic exposure in susceptible hosts, these changes may become pathological by causing neuroinflammation, neurotransmitter, and neuroendocrine imbalances. Soluble PM, such as metals and nano-size particles may translocate across the olfactory, trigeminal, or vagal nerves through retrograde axonal transport, or through systemic circulation which may disrupt the blood-brain barrier (BBB) and deposit in neural tissue. Neuronal deposition of metallic components can have a negative impact through multiple molecular mechanisms. In addition to systemic translocation, the release of pituitary and stress hormones, altered metabolic hormonal status and resultant circulating metabolic milieu, and sympathetically and HPA-mediated changes in immune markers, may secondarily impact the brain through a variety of regulatory adrenal hormone-dependent mechanisms. Several reviews covering air pollution as a risk factor for neuropsychiatric disorders have been published, but no reviews discuss the in-depth intersection between molecular and stress-related neuroendocrine mechanisms, thereby addressing adaptation and susceptibility variations and link to peripheral tissue effects. The purpose of this review is to discuss evidence regarding neurochemical, neuroendocrine, and molecular mechanisms which may contribute to neuropathology from air pollution exposure. This review also covers bi-directional neural and systemic interactions which may raise the risk for air pollution-related systemic illness.

Outdoor Air Pollution Relates to Amygdala Subregion Volume and Apportionment in Early Adolescents

Background

Outdoor air pollution is associated with an increased risk for psychopathology. Although the neural mechanisms remain unclear, air pollutants may impact mental health by altering limbic brain regions, such as the amygdala. Here, we examine the association between ambient air pollution exposure and amygdala subregion volumes in 9-10-year-olds.

Methods

Cross-sectional Adolescent Brain Cognitive DevelopmentSM (ABCD) Study® data from 4,473 participants (55.4% male) were leveraged. Air pollution was estimated for each participant's primary residential address. Using the probabilistic CIT168 atlas, we quantified total amygdala and 9 distinct subregion volumes from T1- and T2-weighted images. First, we examined how criteria pollutants (i.e., fine particulate matter [PM2.5], nitrogen dioxide, ground-level ozone) and 15 PM2.5 components related with total amygdala volumes using linear mixed-effect (LME) regression. Next, partial least squares correlation (PLSC) analyses were implemented to identify relationships between co-exposure to criteria pollutants as well as PM2.5 components and amygdala subregion volumes. We also conducted complementary analyses to assess subregion apportionment using amygdala relative volume fractions (RVFs).

Results

No significant associations were detected between pollutants and total amygdala volumes. Using PLSC, one latent dimension (LD) (52% variance explained) captured a positive association between calcium and several basolateral subregions. LDs were also identified for amygdala RVFs (ranging from 30% to 82% variance explained), with PM2.5 and component co-exposure associated with increases in lateral, but decreases in medial and central, RVFs.

Conclusions

Fine particulate and its components are linked with distinct amygdala differences, potentially playing a role in risk for adolescent mental health problems.

Expose to volatile organic compounds is associated with increased risk of depression: A cross-sectional study

With increasing prevalence rate of depression by years, more attention has been paid to the influence of environmental pollutants on depression, but relationship between exposure to volatile organic compounds (VOCs) and depression is rarely studied. Therefore, this cross-sectional study use the National Center for Health Statistics (NHANES) database (2013-2016 years) to explore association between exposure to multiple VOCs and depression in general population. Multiple linear and logistic regression models were used to analyze the association between urinary VOC metabolism (mVOCs) and depression. To further analyze effect of multiple mVOCs mixed exposure, Bayesian kernel machine regression (BKMR) models were performed. A total of 3240 participants and 16 mVOCs were included in the analysis. Results showed that 10 mVOCs exposure were positively correlated with depression by multiple linear and logistic regression models, especially CYMA and MHBMA3, which also showed significant positive association with depression in BKMR model. Mixed exposure of multiple mVOCs was significantly positively correlated with depression. Gender differences were existed in effects of some VOCs concentrations on depression. AAMA, CYMA and MA had significant positive correlations with depression by women, and DHBMA had significant positive correlations with depression by men. Hence, this study showed that exposing to VOCs might have negative impacts on depression, and impact of CYMA and MHBMA3 on depression may be more evident, which provide new ideas for prevention and control of depression. But further research and exploration are needed to clarify the mechanism and influence factors of this relationship, to demonstrate the reliability of these relationship.

A genome-wide gene-environmental interaction study identified novel loci for the relationship between ambient air pollution exposure and depression, anxiety

BACKGROUND

Genetic factors and environmental exposures, including air pollution, contribute to the risk of depression and anxiety. While the association between air pollution and depression and anxiety has been established in the UK Biobank, there has been limited research exploring this relationship from a genetic perspective.

METHODS

Based on individual genotypic and phenotypic data from a cohort of 104,385 participants in the UK Biobank, a polygenic risk score for depression and anxiety was constructed to explore the joint effects of nitric oxide (NO), nitrogen dioxide (NO2), particulate matter (PM) with a diameter of ⩽2.5 μm (PM2.5) and 2.5-10 μm (PMcoarse) with depression and anxiety by linear and logistic regression models. Subsequently, a genome-wide gene-environmental interaction study (GWEIS) was performed using PLINK 2.0 to identify the genes interacting with air pollution for depression and anxiety.

RESULTS

A substantial risk of depression and anxiety development was detected in participants exposed to the high air pollution concomitantly with high genetic risk. GWEIS identified 166, 23, 18, and 164 significant candidate loci interacting with NO, NO2, PM2.5, and PMcoarse for Patient Health Questionnaire-9 (PHQ-9) score, and detected 44, 10, 10, and 114 candidate loci associated with NO, NO2, PM2.5, and PMcoarse for General Anxiety Disorder (GAD-7) score, respectively. And some significant genes overlapped among four air pollutants, like TSN (rs184699498, PNO2 = 3.47 × 10-9; rs139212326, PPM2.5 = 1.51 × 10-8) and HSP90AB7P(rs150987455, PNO2 = 1.63 × 10-11; rs150987455, PPM2.5 = 7.64 × 10-11), which were common genes affecting PHQ-9 score for both NO2 and PM2.5.

CONCLUSION

Our study identified the joint effects of air pollution with genetic susceptibility on the risk of depression and anxiety, and provided several novel candidate genes for the interaction, contributing to an understanding of the genetic architecture of depression and anxiety.

Residential air pollution, greenspace, and adverse mental health outcomes in the U.S. Gulf Long-term Follow-up Study

Air pollution and greenness are environmental determinants of mental health, though existing evidence typically considers each exposure in isolation. We evaluated relationships between co-occurring air pollution and greenspace levels and depression and anxiety. We estimated cross-sectional associations among 9015 Gulf Long-term Follow-up Study participants living in the southeastern U.S. who completed the Patient Health Questionnaire-9 (depression: score ≥ 10) and Generalized Anxiety Disorder Questionnaire-7 (anxiety: score ≥ 10). Participant residential addresses were linked to annual average concentrations of particulate matter (1 km PM2.5) and nitrogen dioxide (1 km NO2), as well as satellite-based greenness (2 km Enhanced Vegetation Index (EVI)). We used adjusted log-binomial regression to estimate prevalence ratios (PR) and 95 % confidence intervals (CI) for associations between exposures (quartiles) and depression and anxiety. In mutually adjusted models (simultaneously modeling PM2.5, NO2, and EVI), the highest quartile of PM2.5 was associated with increased prevalence of depression (PR = 1.17, 95 % CI: 1.06-1.29), whereas the highest quartile of greenness was inversely associated with depression (PR = 0.89, 95 % CI: 0.80-0.99). Joint exposure to greenness mitigated the impact of PM2.5 on depression (PRPM only = 1.20, 95 % CI: 1.06-1.36; PRPM+green = 0.98, 95 % CI: 0.83-1.16) and anxiety (PRPM only = 1.10, 95 % CI: 1.00-1.22; PRPM+green = 0.95, 95 % CI: 0.83-1.09) overall and in subgroup analyses. Observed associations were stronger in urbanized areas and among nonwhite participants, and varied by neighborhood deprivation. NO2 exposure was not independently associated with depression or anxiety in this population. Relationships between PM2.5, greenness, and depression were strongest in the presence of characteristics that are highly correlated with lower socioeconomic status, underscoring the need to consider mental health as an environmental justice issue.

Neurodegenerative pathways and metabolic changes in the hippocampus and cortex of mice exposed to urban particulate matter: Insights from an integrated interactome analysis

Recently, urban particulate matter (UPM) exposure has been associated with the development of brain disorders. This study uses bioinformatic analyses to elucidate the molecular unexplored mechanisms underlying the effects of UPM exposure on the brain. Mice are exposed to UPM (from 3 days to 20 weeks), and their behavioral patterns measured. We measure pathology and gene expression in the hippocampus and cortical regions of the brain. An integrated interactome of genes is established, which enriches information on metabolic processes. Using this network, we isolate the core genes that are differentially expressed in the samples. We observe cognitive loss and pathological changes in the brains of mice at 16 or 20 weeks of exposure. Through network analysis of core-differential genes and measurement of pathway activity, we identify differences in the response to UPM exposure between the hippocampus and cortex. However, neurodegenerative disease pathways are implicated in both tissues following short-term exposure to UPM. There were also significant changes in metabolic function in both tissues depending on UPM exposure time. Additionally, the cortex of UPM-exposed mice shows more similarities with psychiatric disorders than with neurodegenerative diseases. The connectivity map database is used to isolate genes contributing to changes in expression due to UPM exposure. New approaches for inhibiting or preventing the brain damage caused by UPM exposure can be developed by targeting the functions and selected genes identified in this study.

How does the macroenvironment influence brain and behaviour-a review of current status and future perspectives

The environment influences brain and mental health, both detrimentally and beneficially. Existing research has emphasised the individual psychosocial 'microenvironment'. Less attention has been paid to 'macroenvironmental' challenges, including climate change, pollution, urbanicity, and socioeconomic disparity. Notably, the implications of climate and pollution on brain and mental health have only recently gained prominence. With the advent of large-scale big-data cohorts and an increasingly dense mapping of macroenvironmental parameters, we are now in a position to characterise the relation between macroenvironment, brain, and behaviour across different geographic and cultural locations globally. This review synthesises findings from recent epidemiological and neuroimaging studies, aiming to provide a comprehensive overview of the existing evidence between the macroenvironment and the structure and functions of the brain, with a particular emphasis on its implications for mental illness. We discuss putative underlying mechanisms and address the most common exposures of the macroenvironment. Finally, we identify critical areas for future research to enhance our understanding of the aetiology of mental illness and to inform effective interventions for healthier environments and mental health promotion.

Mendelian study on air pollution and membranous nephropathy outcomes associations

Membranous nephropathy (MN) is an autoimmune disease of the kidney glomerulus, which mainly leads to nephrotic syndrome. This study investigates the associations between air pollution and MN risk and from an epigenomic perspective. In this study, we examine the associations between genetically predicted deoxyribonucleic acid methylation related to air pollution and MN risk. The data of air pollution included particulate matter (PM) with a diameter of 2.5 µm or less (PM2.5), PM with a diameter between 2.5 and 10 µm (PM2.5-10), PM with a diameter of 10 µm or less (PM10), nitrogen dioxide, and nitrogen oxides. Inverse variance weighted method was used as the main analysis method, and weighted median model and Mendelian randomization-Egger methods were selected for quality control. To assess the reliability of the results of the analyses, heterogeneity test, horizontal pleiotropy test, and the leave-one-out method were applied. There was a causal relationship between nitrogen oxides and MN risk (P = .010). Other types of air pollution were found no statistical association with MN disease (PM2.5: P = .378; PM2.5-10: P = .111; PM10: P = .035; nitrogen dioxide: P = .094). There was no heterogeneity or pleiotropy in the results. Our study suggests the association between nitrogen oxides and membrane nephropathy (MN) risk from the genetic perspective. This provides a theoretical basis for the prevention of MN disease.

Association of short-term exposure to ambient fine particulate matter and ozone with outpatient visits for anxiety disorders: A hospital-based case-crossover study in South China

BACKGROUND

The short-term adverse effects of ambient fine particulate matter (PM2.5) and ozone (O3) on anxiety disorders (ADs) remained inconclusive.

METHODS

We applied an individual-level time-stratified case-crossover study, which including 126,112 outpatient visits for ADs during 2019-2021 in Guangdong province, China, to investigate the association of short-term exposure to PM2.5 and O3 with outpatient visits for ADs, and estimate excess outpatient visits in South China. Daily residential air pollutant exposure assessments were performed by extracting grid data (spatial resolution: 1 km × 1 km) from validated datasets. We employed the conditional logistic regression model to quantify the associations and excess outpatient visits.

RESULTS

The results of the single-pollutant models showed that each 10 μg/m3 increase of PM2.5 and O3 exposures was significantly associated with a 3.14 % (95 % confidence interval: 2.47 %, 3.81 %) and 0.88 % (0.49 %, 1.26 %) increase in odds of outpatient visits for ADs, respectively. These associations remained robust in 2-pollutant models. The proportion of outpatient visits attributable to PM2.5 and O3 exposures was up to 7.20 % and 8.93 %, respectively. Older adults appeared to be more susceptible to PM2.5 exposure, especially in cool season, and subjects with recurrent outpatient visits were more susceptible to O3 exposure.

LIMITATION

As our study subjects were from one single hospital in China, it should be cautious when generalizing our findings to other regions.

CONCLUSION

Short-term exposure to ambient PM2.5 and O3 was significantly associated with a higher odds of outpatient visits for ADs, which can contribute to considerable excess outpatient visits.

A Systematic Review of Air Pollution Exposure and Brain Structure and Function during Development

Objectives

Air pollutants are known neurotoxicants. In this updated systematic review, we evaluate new evidence since our 2019 systematic review on the effect of outdoor air pollution exposure on childhood and adolescent brain structure and function as measured by magnetic resonance imaging (MRI).

Methods

Using PubMed and Web of Science, we conducted an updated literature search and systematic review of articles published through March 2024, using key terms for air pollution and functional and/or structural MRI. Two raters independently screened all articles using Covidence and implemented the risk of bias instrument for systematic reviews informing the World Health Organization Global Air Quality Guidelines.

Results

We identified 222 relevant papers, and 14 new studies met our inclusion criteria. Including six studies from our 2019 review, the 20 publications to date include study populations from the United States, Netherlands, Spain, and United Kingdom. Studies investigated exposure periods spanning pregnancy through early adolescence, and estimated air pollutant exposure levels via personal monitoring, geospatial residential estimates, or school courtyard monitors. Brain MRI occurred when children were on average 6-14.7 years old; however, one study assessed newborns. Several MRI modalities were leveraged, including structural morphology, diffusion tensor imaging, restriction spectrum imaging, arterial spin labeling, magnetic resonance spectroscopy, as well as resting-state and task-based functional MRI. Air pollutants were associated with widespread brain differences, although the magnitude and direction of findings are largely inconsistent, making it difficult to draw strong conclusions.

Conclusion

Prenatal and childhood exposure to outdoor air pollution is associated with structural and functional brain variations. Compared to our initial 2019 review, publications doubled-an increase that testifies to the importance of this public health issue. Further research is needed to clarify the effects of developmental timing, along with the downstream implications of outdoor air pollution exposure on children's cognitive and mental health.

Neuroinflammation and Brain Health Risks in Veterans Exposed to Burn Pit Toxins

Military burn pits, used for waste disposal in combat zones, involve the open-air burning of waste materials, including plastics, metals, chemicals, and medical waste. The pits release a complex mixture of occupational toxic substances, including particulate matter (PM), volatile organic compounds (VOCs), heavy metals, dioxins, and polycyclic aromatic hydrocarbons (PAHs). Air pollution significantly impacts brain health through mechanisms involving neuroinflammation. Pollutants penetrate the respiratory system, enter the bloodstream, and cross the blood-brain barrier (BBB), triggering inflammatory responses in the central nervous system (CNS). Chronic environmental exposures result in sustained inflammation, oxidative stress, and neuronal damage, contributing to neurodegenerative diseases and cognitive impairment. Veterans exposed to burn pit toxins are particularly at risk, reporting higher rates of respiratory issues, neurological conditions, cognitive impairments, and mental health disorders. Studies demonstrate that Veterans exposed to these toxins have higher rates of neuroinflammatory markers, accelerated cognitive decline, and increased risks of neurodegenerative diseases. This narrative review synthesizes the research linking airborne pollutants such as PM, VOCs, and heavy metals to neuroinflammatory processes and cognitive effects. There is a need for targeted interventions to mitigate the harmful and escalating effects of environmental air pollution exposures on the CNS, improving public health outcomes for vulnerable populations, especially for Veterans exposed to military burn pit toxins.

What do Climate Change, Nutrition, and the Environment Have to do With Mental Health?

Climate change is becoming the most significant global challenge and must be addressed on a global scale. At the time that this article is being written, the planetary heat in 2023 was the hottest on record. Similarly, the World Health Organization reports that 99% of the world's population lives in regions of unhealthy air pollution. Similarly, depression has become one of the leading causes of global mental and physical disabilities, and the impact of depression is predicted to only worsen over the next 25 years. It is interesting to note that climate experts often overlook the adoption of nutrition via a whole plant-based diet as a solution to both mental illness and climate change. In this review, we will touch upon the role of nutrition in gut microbiota and mental health, the impact diet has on greenhouse gases, the role of ultra-processed food, and environmental factors such as air pollution and increasing planetary heat and their growing impacts on mental health. In the end, the promotion of plant-based foods has the potential to improve personal mental and physical health while improving planetary health.

Long-term Exposure to Ambient Air Pollution and its Association with Mental Well-Being, Depression and Anxiety: A Nationally Representative Study

INTRODUCTION

Exposure to ambient air pollution may play a role in the onset of common mental disorders like depressive and anxiety disorders. The association of long-term exposure to particles smaller than 10 μm (PM10) with these diseases remains unclear. This study aimed to estimate the association of long-term exposure to PM10 with mental well-being and the frequency of probable diagnosis of common mental disorders.

METHODS

A nationally representative cross-sectional study was done in mainland Portugal. Long-term exposure was estimated through one-year average concentrations of PM10, calculated with data from the Portuguese Environment Agency, attributed individually considering individuals' postal codes of residence. The mental well-being and the probable diagnosis of common mental disorders were ascertained through the five-item Mental Health Inventory scale. Linear and Robust Poisson regression models were computed to estimate change percentages, prevalence ratios (PR), and their 95% confidence intervals (95% CI).

RESULTS

The median (interquartile range) concentration of PM10 was 18.6 (15.3 - 19.3) μg/m3. The mental well-being score was 72 (56 - 84) points, on a scale from 0 to 100. A probable diagnosis of common mental disorders was found in 22.7% (95% CI: 20.0 to 25.6). Long-term exposure to PM10 was associated with a non-statistically significant decrease in the mental well-being score [for each 10 μg/m³ increment in one-year average PM10 concentrations, there was a 2% (95% CI: -8 to 4) decrease], and with a non-statistically significant increase in the common mental health frequency (PR = 1.012, 95% CI: 0.979 to 1.045).

CONCLUSION

We did not find statistically significant associations between long-term exposure to PM10 and mental well-being or the frequency of probable diagnosis of common mental disorders. These results may be explained by the reduced variability in the exposure values, given the geographical distribution and functioning of the network of air quality monitoring stations. This study contributes with evidence for low levels of air pollutants, being one of the first to adjust for individual and aggregate-level variables. Moreover, to the best of our knowledge, this was the first nationally representative, population-based study conducted on the Portuguese population using real-life data. Maintaining a robust and nationwide air quality monitoring network is essential for obtaining quality exposure data.

Male-biased vulnerability of mouse brain tryptophan/kynurenine and glutamate systems to adolescent exposures to concentrated ambient ultrafine particle air pollution

Air pollution (AP) exposures have been associated with numerous neurodevelopmental and psychiatric disorders, including autism spectrum disorder, attention deficit hyperactivity disorder and schizophrenia, all male-biased disorders with onsets from early life to late adolescence/early adulthood. While prior experimental studies have focused on effects of AP exposures during early brain development, brain development actually extends well into early adulthood. The current study in mice sought to extend the understanding of developmental brain vulnerability during adolescence, a later but significant period of brain development and maturation to the ultrafine particulate (UFPs) component of AP, considered its most reactive component. Additionally, it examined adolescent response to UFPs when preceded by earlier developmental exposures, to ascertain the trajectory of effects and potential enhancement or mitigation of adverse consequences. Outcomes focused on shared features associated with multiple neurodevelopmental disorders. For this purpose, C57Bl/6 J mice of both sexes were exposed to ambient concentrated UFPs or filtered air from PND (postnatal day) 4-7 and PND10-13, and again at PND39-42 and 45-49, resulting in 3 exposure postnatal/adolescent treatment groups per sex: Air/Air, Air/UFP, and UFP/UFP. Features common to neurodevelopmental disorders were examined at PND50. Mass exposure concentration from postnatal exposure averaged 44.34 μg/m3 and the adolescent exposure averaged 49.18 μg/m3. Male brain showed particular vulnerability to UFP exposures in adolescence, with alterations in frontal cortical and striatal glutamatergic and tryptophan/serotonergic neurotransmitters and concurrent reductions in levels of astrocytes in corpus callosum and in serum cytokine levels, with combined exposures resulting in significant reductions in corpus callosum myelination and serum corticosterone. Reductions in serum corticosterone in males correlated with reductions in neurotransmitter levels, and reductions in striatal glutamatergic function specifically correlated with reductions in corpus callosum astrocytes. UFP-induced changes in neurotransmitter levels in males were mitigated by prior postnatal exposure, suggesting potential adaptation, whereas reductions in corticosterone and in corpus callosum neuropathological effects were further strengthened by combined postnatal and adolescent exposures. UFP-induced changes in females occurred primarily in striatal dopamine systems and as reductions in serum cytokines only in response to combined postnatal and adolescent exposures. Findings in males underscore the importance of more integrated physiological assessments of mechanisms of neurotoxicity. Further, these findings provide biological plausibility for an accumulating epidemiologic literature linking air pollution to neurodevelopmental and psychiatric disorders. As such, they support a need for consideration of the regulation of the UFP component of air pollution.

Prenatal exposure to air pollution and maternal depression: Combined effects on brain aging and mental health in young adulthood

INTRODUCTION

Both maternal depression problems during pregnancy and prenatal exposure to air pollution have been associated with changes in the brain as well as worse mood and anxiety in the offspring in adulthood. However, it is not clear whether these effects are independent or whether and how they might interact and impact the brain age and mental health of the young adult offspring.

METHODS

A total of 202 mother-child dyads from a prenatal birth cohort were assessed for maternal depression during pregnancy through self-report questionnaires administered in the early 90s, exposure to air pollutants (Sulfur dioxide [SO2], nitrogen oxides [NOx], and suspended particle matter [SPM]) during each trimester based on maternal address and air quality data, mental health of the young adult offspring (28-30 years of age; 52% men, all of European ancestry) using self-report questionnaires for depression (Beck Depression Inventory), mood dysregulation (Profile of Mood States), anxiety (State-Trait Anxiety Inventory), and psychotic symptoms (Schizotypal Personality Questionnaire), and brain age, estimated from structural magnetic resonance imaging (MRI) and previously published neuroanatomical age prediction model using cortical thickness maps. The brain age gap estimate (BrainAGE) was computed by subtracting structural brain age from chronological age. Trajectories of exposure to air pollution during pregnancy were assessed using Growth Mixture Modeling. The interactions of prenatal depression and prenatal exposure to air pollutants on adult mental health and BrainAGE were assessed using hierarchical linear regression.

RESULTS

We revealed two distinct trajectories of exposure to air pollution during pregnancy: "early exposure," characterized by high exposure during the first trimester, followed by a steady decrease, and "late exposure," characterized by low exposure during the first trimester, followed by a steady increase in the exposure during the subsequent trimesters. Maternal depression during the first half of pregnancy interacted with NOX exposure trajectory, predicting mood dysregulation and schizotypal symptoms in young adults. In addition, maternal depression during the second half of pregnancy interacted with both NOx and SO2 exposure trajectories, respectively, and predicted BrainAGE in young adults. In those with early exposure to NOx, maternal depression during pregnancy was associated with worse mental health and accelerated brain aging in young adulthood. In contrast, in those with early exposure to SO2, maternal depression during pregnancy was associated with slower brain aging in young adulthood.

CONCLUSIONS

Our findings provide the first evidence of the combined effects of prenatal exposure to air pollution and maternal depression on mental health outcomes and brain age in young adult offspring. Moreover, they point out the importance of the timing and trajectory of the exposure during prenatal development.

Rethinking professional boundaries: the climate crisis and brain health

Since climate change affects psychiatric, neurological and neuropsychological disorders, as well as brain development, the Irish Doctors for the Environment working group on mental health has changed its title and remit to brain health. Mental health professionals need to respond coherently and effectively to the climate crisis. This need challenges traditional professional, disciplinary and academic boundaries and demands a holistic, person-centred approach. We propose that meeting this challenge is vital if the public, policy-makers and legislators are to grasp the full extent of the significance of climate's impact on brain health.

Are protected characteristics associated with mental health care inequalities in the adult UK general population? a cross-sectional study

This study investigates the association between protected characteristics and inequalities in mental health care in the UK. Multinomial regression was used to model the association between protected characteristics and self-reported distress. Data was extracted from waves 6-10 (2014-2019) of the UK Household Longitudinal Study. Two risk categories were constructed: "undiagnosed distress" referred to a General Health Questionnaire-12 (GHQ-12) score above "caseness" along with no history of mental health diagnosis; "diagnosis without self-report symptoms" referred to a GHQ-12 score consistently below "caseness" within the study time frame but having received a mental health diagnosis. Compared to people without a disability, people with a disability are at considerably greater risk of both undiagnosed distress (Relative risk ratios (RRR) 2.76; Confidence Interval (CI): 2.55, 2.99) and diagnosis without self-reported symptoms (RRR 3.61; CI: 2.80, 4.66). Likewise, women were more likely than men to report undiagnosed distress (RRR = 1.49; CI: 1.38,1.61) or a diagnosis without self-reported symptoms (RRR = 1.38; CI: 1.08, 1.76. Lesbian, gay, and bisexual people are at greater risk of undiagnosed distress compared with heterosexual people (RRR 1.42; CI: 1.19, 1.70). Adults aged 16-24 years were at greatest risk compared to all other age groups. People from a minority ethnic background had a reduced risk of diagnosis without self-report symptoms compared with people from a White ethnic background (RRR 0.34; CI: 0.20, 0.61). Education, employment and income variables moderated some of these associations. This is the first study to examine diagnosis without self-report symptoms alongside undiagnosed distress. Findings suggest that addressing inequality in mental health care requires increased understanding of the needs and strengths within different groups and to provide appropriate forms of social, medical or psychosocial intervention rather than a singular focus on increasing detection, diagnosis and treatment. People with a disability appear to be at greatest disadvantage, requiring greater attention in policy and practice.

Outdoor air pollution and brain development in childhood and adolescence

Exposure to outdoor air pollution has been linked to adverse health effects, including potential widespread impacts on the CNS. Ongoing brain development may render children and adolescents especially vulnerable to neurotoxic effects of air pollution. While mechanisms remain unclear, promising advances in human neuroimaging can help elucidate both sensitive periods and neurobiological consequences of exposure to air pollution. Herein we review the potential influences of air pollution exposure on neurodevelopment, drawing from animal toxicology and human neuroimaging studies. Due to ongoing cellular and system-level changes during childhood and adolescence, the developing brain may be more sensitive to pollutants' neurotoxic effects, as a function of both timing and duration, with relevance to cognition and mental health. Building on these foundations, the emerging field of environmental neuroscience is poised to further decipher which air toxicants are most harmful and to whom.