Association of Long-term Exposure to Ambient Air Pollution With Cognitive Decline and Alzheimer's Disease-Related Amyloidosis

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.

The Association of Ambient Air Pollution With Dynamic Transitions of Cataract and Dementia: A UK Biobank Study

BACKGROUND AND OBJECTIVES

Air pollution has a detrimental effect on the risk of dementia and cataract. This study aimed to investigate the association of air pollution with the dynamic transitions of cataract and dementia.

RESEARCH DESIGN AND METHODS

We enrolled 409,608 participants (mean age: 56.4 years; 45.9% male) free of cataract and dementia at baseline from the UK Biobank with follow-up until 30 September 2023. We estimated the annual average concentrations of particulate matter (PM) with aerodynamic diameter ≤ 2.5 μm (PM2.5), ≤ 10 μm (PM10), nitrogen dioxide (NO2), and nitrogen oxides (NOx) at 2010. We employed multi-state models to assess the association between air pollution and the dynamic transitions of cataract and dementia after adjusting for potential confounders.

RESULTS

During a median follow-up of 14.5 years, 51,786 participants were diagnosed with cataracts, and 6068 with dementia. PM2.5 showed the strongest association with the transitions from healthy to cataract (hazard ratio [HR], 1.05; 95% confidence interval [CI], 1.04-1.06; p < 0.001), from healthy to dementia (HR, 1.05; 95% CI, 1.02-1.09; p = 0.002), from cataract to comorbidity (HR, 1.07; 95% CI, 1.00-1.15; p = 0.048), from healthy to death (HR, 1.03; 95% CI, 1.01-1.05; p < 0.001), and from cataract to death (HR, 1.06; 95% CI, 1.02-1.10; p = 0.007).

CONCLUSION AND IMPLICATIONS

Our study suggested that the long-term exposure to air pollution was associated an increased risk of the transitions from health to incident cataract, dementia or the progression of both conditions. This implied the importance of implementing air pollution control strategies to prevent cataract and dementia.

Synergistic impact of air pollution and artificial light at night on memory disorders: a nationwide cohort analysis

BACKGROUND

Air pollutants and outdoor artificial light at night (ALAN) are known health risks, with established effects on respiratory and cardiovascular health. However, their impact on cognitive function, particularly neurodegenerative diseases like Alzheimer's, remains poorly understood.

METHODS

Using data from the China Health and Retirement Longitudinal Study (CHARLS) and the China Family Panel Studies (CFPS), including 44,689 participants, memory impairment (Memrye) was defined by self-reported memory-related diseases. Cox regression models were applied to assess the relationship between pollutants, ALAN exposure, and Memrye. Interaction analyses evaluated the combined effects using relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy index (S). Biomarker analyses and stepwise causal mediation examined the underlying mechanisms.

RESULTS

Air pollutants and ALAN were significantly associated with Memrye (p < 0.05), with hazard ratios (HR) ranging from 1.010 to 1.343. Synergistic effects were observed, such as for PM2.5 and ALAN, with RERI, AP, and S values of 0.65 (0.33, 0.97), 0.30 (0.26, 0.34), and 1.43 (1.21, 1.65), respectively. Biomarker analyses showed significant correlations between pollutants, glucose, cholesterol, and uric acid, while ALAN was negatively associated with glucose and uric acid. Mediation analyses indicated that PM2.5, NO2, and ALAN indirectly affected Memrye through biomarkers, accounting for 1.07-8.28% of the total effects.

CONCLUSION

Air pollution and ALAN exposure are linked to memory impairment, with combined effects potentially amplifying risk. Biomarkers play a key role in mediating these effects, suggesting a need for targeted public health measures to mitigate these environmental health risks.

Association between chronic PM2.5 exposure and neurodegenerative biomarkers in adults from critically polluted area

BACKGROUND

Air pollution is a significant public health concern, increasingly recognized for its association with adverse health outcomes including neurodegenerative and neuroinflammatory conditions. The present study aimed to characterize plasma levels of key biomarkers related to neurodegeneration and neuroinflammation among middle-aged to elderly adults living in areas designated as critically polluted.

METHODS

A total of 202 adults, aged 41 to 60 years, residing in CPA (CEPI > 70) for over ten years were recruited in the study. The exposures of air pollutant were measured as per the established protocols by CPCB. The plasma levels of neurodegenerative markers (Aβ(1-42), Total τ, α-Synuclein, BDNF and GFAP) were estimated using commercially available ultra-sensitive ELISA kits. The data analysis was performed through mean and standard deviation, percentile distribution and multivariate logistic regression using SPSS 26.0.

RESULTS

This study confirmed the elevated PM2.5 levels at the study location exceeding the regulatory limits. Women exhibited relatively higher Amyloid Aβ(1-42), α-Synuclein and GFAP levels, while men exhibited relatively higher Total τ, & BDNF levels. Further, older participants (aged 50 - 60 years) exhibited higher levels of all markers but α-Synuclein, as compared to the younger peers (aged 40 - 50 years). A weak positive trend (p = 0.08) was observed for α-Synuclein with prolonged exposure.

CONCLUSION

This study is among the first community-based investigations in India to assess plasma levels of neurodegenerative and neuroinflammatory biomarkers in apparently healthy adults chronically exposed to high ambient air pollution. By integrating chronic exposure data from a Critically Polluted Area (CEPI > 70) with biomarker profiling, the study offers early insights into potential neurobiological alterations associated with environmental pollutants, highlighting sex- and age-specific vulnerabilities. These findings emphasize the importance of considering environmental influences in neurodegenerative disease research and the potential need for tailored health interventions.

Factors associated with age at tau pathology onset and time from tau onset to dementia

INTRODUCTION

Elevated tau is temporally proximal to dementia onset but less is known about factors influencing T+ onset age and time to dementia following T+ in Alzheimer's disease. We used sampled iterative localized approximation (SILA) estimated T+ onset age (ETOA) to investigate factors associated with T+ age and time from T+ to dementia onset in ADNI.

METHODS

Using SILA-estimated A+ and T+ onset ages derived from 18F-Flortaucipir, 18F-Florbetapir, and 18F-Florbetaben PET and Cox proportional hazards and accelerated failure time models, we analyzed APOE, sex, amyloid burden, age, educational attainment, and literacy associations with ETOA and time from T+ to dementia.

RESULTS

Higher amyloid, APOE-ε4, lower education, and lower literacy associated with younger ETOA. Older ETOA and higher amyloid associated with shorter time from T+ to dementia.

DISCUSSION

This work highlights the prognostic value of ETOA and the need to better characterize factors contributing to ETOA and dementia onset in AD.

The Effects of Air Pollution on Neurological Diseases: A Narrative Review on Causes and Mechanisms

Air pollution has well-documented adverse effects on human health; however, its impact on neurological diseases remains underrecognized. The mechanisms by which various components of air pollutants contribute to neurological disorders are not yet fully understood. This review focuses on key air pollutants, including particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and diesel exhaust particles (DEPs). This paper summarizes key findings on the effects of air pollution on neurological disorders, including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), Alzheimer's disease (AD), and Parkinson's disease (PD). Although the precise biological mechanisms remain to be fully elucidated, evidence suggests that multiple pathways are involved, including blood-brain barrier disruption, oxidative stress, inflammation, and the activation of microglia and astrocytes. This review underscores the role of environmental pollutants as significant risk factors for various neurological diseases and explores their mechanisms of action. By advancing our understanding of these interactions, this work aims to inform new insights for mitigating the adverse effects of air pollution on neurological diseases, ultimately contributing to the establishment of a cleaner and healthier environment for future generations.

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.

The emerging roles of particulate matter-changed non-coding RNAs in the pathogenesis of Alzheimer's disease: A comprehensive in silico analysis and review

Research on epigenetic‒environmental interactions in the development of Alzheimer's disease (AD) has accelerated rapidly in recent decades. Numerous studies have demonstrated the contribution of ambient particulate matter (PM) to the onset of AD. Emerging evidence indicates that non-coding RNAs (ncRNAs), including long non-coding RNAs, circular RNAs, and microRNAs, play a role in the pathophysiology of AD. In this review, we provide an overview of PM-altered ncRNAs in the brain, with emphasis on their potential roles in the pathogenesis of AD. These results suggest that these PM-altered ncRNAs are involved in the regulation of amyloid-beta pathology, microtubule-associated protein Tau pathology, synaptic dysfunction, damage to the blood‒brain barrier, microglial dysfunction, dysmyelination, and neuronal loss. In addition, we utilized in silico analysis to explore the biological functions of PM-altered ncRNAs in the development of AD. This review summarizes the knowns and unknowns of PM-altered ncRNAs in AD pathogenesis and discusses the current dilemma regarding PM-altered ncRNAs as promising biomarkers of AD. Altogether, this is the first thorough review of the connection between PM exposure and ncRNAs in AD pathogenesis, which may offer novel insights into the prevention, diagnosis, and treatment of AD associated with ambient PM exposure.

Comprehensive health risk assessment of urban ambient air pollution (PM2.5, NO2 and O3) in Ghana

Urbanization and industrialization have drastically increased ambient air pollution in urban areas globally from vehicle emissions, solid fuel combustion and industrial activities leading to some of the worst air quality conditions. Air pollution in Ghana causes approximately 28,000 premature deaths and disabilities annually, ranking as a leading cause of mortality and disability-adjusted life years. This study evaluated the annual concentrations of PM2.5, NO2 and O3 in the ambient air of 57 cities in Ghana for two decades using historical and forecasted data from satellite measurements. The study assessed urban air quality and evaluated both carcinogenic and non-carcinogenic health risks associated with human exposure to ambient air pollutants. Alarmingly, our findings revealed the yearly median PM2.5 concentrations (50.79-67.97 µg m-3) to be significantly higher than the WHO recommendation of 5 µg m-3. Tropospheric ozone concentrations (72.21-92.58 µg m-3 ) also exceeded the WHO annual standard of 60 µg m-3. Furthermore, NO2 concentrations (3.65-12.15 µg m-3 ) surpassed the WHO threshold of 10 µg/m³ in multiple cities. Hazard indices indicated that PM2.5 and O3 pose significant non-carcinogenic health risks for younger age groups for a daily exposure duration of three hours and beyond. According to the Air Quality Life Index (AQLI) in our study, exposure to PM2.5 shortens life expectancy by 4.5-6.2 years. The ambient air of the majority (98 %) of the cities was unhealthy for sensitive groups. This study reveals the urgent need for comprehensive air quality policies in Ghanaian cities. It emphasizes the significance of robust real-time monitoring of air pollutants and the investigation of seasonal dust storm effects, to fill data gaps in Ghana and West Africa, facilitating evidence-based interventions that improve urban air quality and public health outcomes.

Air Pollution and Cognitive Impairment Among the Chinese Elderly Population: An Analysis of the Chinese Longitudinal Healthy Longevity Survey (CLHLS)

Cognitive impairment and dementia have long been recognized as growing public health threats. Studies have found that air pollution is a potential risk factor for dementia, but the literature remains inconclusive. This study aimed to evaluate the association between three major air pollutants (i.e., PM2.5, O3, and NO2) and cognitive impairment among the Chinese elderly population. Study participants were selected from the Chinese Longitudinal Health Longevity Survey (CLHLS) after 2005. We define cognitive impairment as a Chinese Mini-Mental-State Exam (CMMSE) score <24. The associations of air pollution with cognitive impairment and CMMSE score were evaluated with a logistic regression model and a linear mixed-effect model with random intercepts, respectively. A total of 3,887 participants were enrolled in this study. Of the 2,882 participants who completed at least one follow-up visit, 931 eventually developed cognitive impairment. In single-pollutant models, we found that yearly average PM2.5 and NO2 as well as warm season O3, were positively associated with cognitive impairment. NO2 remained positively associated with cognitive impairment in the multi-pollutant model. The linear mixed-effect models revealed that warm season O3 and yearly average NO2 were significantly associated with decreased CMMSE scores. Our research has established a positive association between cognitive impairment and air pollution in China. These findings underscore the imperative for the next iteration of China's Air Pollution Prevention and Control Action Plan to broaden its focus to encompass gaseous air pollutants since mitigating single air pollutant is insufficient to protect the aging population.

Longitudinal associations between air pollution and incident dementia as mediated by MRI-measured brain volumes in the UK Biobank

BACKGROUND

Although there is increasing evidence that environmental exposures are associated with the risk of neurodegenerative conditions, there is still limited mechanistic evidence evaluating potential mediators in human populations.

METHODS

UK Biobank is a large long-term study of 500,000 adults enrolled from 2006 to 2010 age 40-69 years. ICD-10 classified reports of dementia cases up to 2022 (Alzheimer's disease, vascular dementia, dementia in other classified diseases, and unspecified dementia) were identified from health record linkage. Estimates of residential air pollution, traffic noise, and greenspace exposure have been modelled. Structural brain MRI was conducted from 2014 to 2022, with brain volumes relevant to dementia identified a priori. Associations between environmental exposures, brain volumes, and dementia cases (diagnosed post-MRI) were tested using linear and logistic regression and adjusted for age, sex, household income, ethnicity, education, smoking, and area-level deprivation. Mediation of exposure-outcome associations by plausible brain volumes (those associated with both environmental exposure and dementia outcomes) were modelled using the quasi-Bayesian Monte Carlo method (N = 34,817-39,772).

RESULTS

Small but significant mediating effects (2%-8% of relationships mediated) were observed between PM2.5abs exposure and dementia risk by reduced total brain volume, NOx and Alzheimer's disease risk by reduced peripheral cortical grey matter, PM2.5abs and vascular dementia risk by reduced peripheral cortical grey matter, PM2.5abs and other dementia risk by reduced total grey matter, and PM10 and other dementia risk by reduced total grey matter. Greenspace and noise were not associated with dementia outcomes in the subset of the cohort providing brain imaging data.

CONCLUSIONS

This study adds to existing evidence of associations between environmental exposures and dementia outcomes. Our findings provide novel evidence that differences in brain volume may mediate these relationships. Future research is required to prove this mechanism and establish the other mechanisms through which exposure to air pollution might increase dementia risk.

Role of microglia polarization induced by glucose metabolism disorder in the cognitive impairment of mice from PM2.5 exposure

Studies have found that PM2.5 can damage the brain, accelerate cognitive impairment, and increase the risk of developing a variety of neurodegenerative diseases. However, the potential molecular mechanisms by which PM2.5 causes learning and memory problems are yet to be explored. In this study, we evaluated the neurotoxic effects in mice after 12 weeks of PM2.5 exposure, and found that this exposure resulted in learning and memory disorders, pathological brain damage, and M1 phenotype polarization on microglia, especially in the hippocampus. The severity of this damage increased with increasing PM2.5 concentration. Proteomic analysis, as well as validation results, suggested that PM2.5 exposure led to abnormal glucose metabolism in the mouse brain, which is mainly characterized by significant expression of hexokinase, phosphofructokinase, and lactate dehydrogenase. We therefore administered the glycolysis inhibitor 2-deoxy-d-glucose (2-DG) to the mice exposed to PM2.5, and showed that inhibition of glycolysis by 2-DG significantly alleviated PM2.5-induced hippocampal microglia M1 phenotype polarization, and reduced the release of inflammatory factors, improved synaptic structure and related protein expression, which alleviated the cognitive impairment induced by PM2.5 exposure. In summary, our study found that abnormal glucose metabolism-mediated inflammatory polarization of microglia played a role in learning and memory disorders in mice exposed to PM2.5. This study provides new insights into the neurotoxicity caused by PM2.5 exposure, and provides some theoretical references for the prevention and control of cognitive impairment induced by PM2.5 exposure.

Effects of major air pollutants on cognitive function in middle-aged and elderly adults: Panel data evidence from China Health and Retirement Longitudinal Study

Background

Although numerous studies have discussed about the impact of air pollution on cognitive function, a consensus has yet to be reached, necessitating further exploration of their relationship. The aim of this study is to reveal the effects of major air pollutants on cognitive function in Chinese middle-aged and older adults, while considering the lagged effects of pollution.

Methods

Panel data were constructed by integrating the air pollutants concentration (particulate matter diameter ≤1 µm (μm) (PM1), PM2.5, PM10, nitrogen dioxide (NO2), and ozone (O3)) among 28 provinces in China and the personal characteristics from China Health and Retirement Longitudinal Study participants during the period of 2011-2015. To explore the effects of single pollutants and their interactions on cognitive function, panel linear regression using ordinary least squares method was employed, and first-order lag effects (two-year interval) of air pollution were introduced into the models.

Results

Our study revealed that, after adjusting for confounding factors, higher levels of particulate matter (PM1, coefficient (Coef.) = -0.093, P = 0.001; PM2.5, Coef. = -0.051, P = 0.001; PM10, Coef. = -0.030, P = 0.001) and NO2 (Coef. = -0.094, P = 0.006) were associated with lower cognitive function scores among the participants. Moreover, the interaction between the five major pollutants exhibited a negative effect on cognitive function(Coef. = -2.89, P = 0.004).

Conclusions

PM1, PM2.5, PM10 have detrimental effects on the cognitive function of middle-aged and elderly adults in China, where increasing particle diameter correlates with a less negative impacts, providing theoretical underpinnings for the formulation of environmental protection policies.

Frontiers and hotspots evolution between air pollution and Alzheimer's disease: A bibliometric analysis from 2013 to 2023

In recent years, the study of air pollution has received increasing attention from researchers, but a summary of Alzheimer's disease (AD) and air pollution is missed. Through combing the documents in the core dataset of Web of Science, this study analyzes current research based on specific keywords. CiteSpace and VOSviewer perform statistical analysis of measurement metrics to visualize a network of relevant content elements. The research devotes discussion to the relationship between air pollution and AD. Keyword hotspots include AD, children, oxidative stress, and system inflammation. Overall, 304 documents on air pollution and AD from 2013 to 2023 were retrieved from Web of Science. One hundred twenty-two journals published relevant articles, and the number of articles has increased gradually since the past decade. Research and development in AD and air pollution are progressing rapidly, but there is still a need for more connections with multidisciplinary technologies to explore cutting-edge hotspots.

Exposure to air pollution and cognitive function based on the minimum mental state examination: a systematic review and meta-analysis

Evidence regarding the cognitive effects of air pollution is inconsistent. This study aimed to quantitatively analyze the relationship between air pollutants and cognitive abilities using the Mini-Mental State Examination (MMSE). We systematically searched for studies published until July 1, 2023, and assessed heterogeneity with Cochran's Q test and I² statistics, while publication bias was evaluated using Funnel plots and Egger's test. Out of 380 studies, 17 were included in the meta-analysis. Results demonstrated significant relationship among long-term exposure to PM2.5, O3, and cognitive decline. The pooled RR of cognitive impairment per 10μg/m3 increase were 1.17 for PM2.5 and 1.07 for PM10. Furthermore, there was a significant association between cognitive decline and long-term exposure to PM2.5 (β = -0.30; I2 = 95.30%) and PM10 (β = -0.15; I2 = 87.50%). Our research suggests that long-term exposure to air pollution, especially PM2.5, is a risk factor for cognitive impairment.

The health and economic burden of ozone pollution on Alzheimer's disease and mild cognitive impairment in China

Ozone pollution is increasingly recognized as a serious environmental threat that exacerbates dementia risks, including Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI). Amid rapid industrialization, China faces significant air quality challenges. However, there has been a scarcity of detailed studies assessing the health and economic impacts of ozone pollution on these conditions. This study aims to address this gap by utilizing the BenMap-CE tool and incorporating parameters obtained from systematic reviews of epidemiological studies, official statistics, and weighted averages, to accurately quantify the effects of ozone exposure in China. This research evaluated the health and economic burdens at both national and provincial levels, focusing on the additional impacts attributed to increased ozone levels. The results reveal that in 2023, compared to 2015, ozone pollution contributed to approximately 110,000 new cases (5.6 per 10,000) of AD and 1.6 million new cases (81.7 per 10,000) of MCI, imposing significant economic costs of about US $1200 million for AD and US $18,000 million for MCI, based on 2015 dollar values. Additionally, our projections indicate that reducing the 2023 ozone concentrations to 70 μg/m3 could significantly curb these conditions, potentially preventing over 210,000 new AD cases (10.7 per 10,000) and 2.9 million (148.1 per 10,000) MCI cases. Such reductions are projected to yield substantial economic benefits, estimated at US $2200 million for AD and US $34,000 million for MCI (2015 dollar values). These findings underscore the profound implications of ozone pollution on public health and the economy in China, highlighting the urgent need for effective ozone management strategies to mitigate these impacts.

Exposure to coal dust exacerbates cognitive impairment by activating the IL6/ERK1/2/SP1 signaling pathway

Coal dust (CD) is a common pollutant, and epidemiological surveys indicate that long-term exposure to coal dust not only leads to the occurrence of pulmonary diseases but also has certain impacts on cognitive abilities. However, there is little open-published literature on the effects and specific mechanisms of coal dust exposure on the cognition of patients with Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). An animal model has been built in this study with clinical population samples to explore the changes in neuroinflammation and cognitive abilities with coal dust exposure. In the animal model, compared to C57BL/6 mice, APP/PS1 mice exposed to coal dust exhibited more severe cognitive impairment, accompanied by significantly elevated levels of neuroinflammatory factors Apolipoprotein E4 (AOPE4) and Interleukin-6 (IL6) in the hippocampus, and more severe neuronal damage. In clinical sample sequencing, it was found that there is significant upregulation of AOPE4, neutrophils, and IL6 expression in the peripheral blood of MCI patients compared to normal individuals. Mechanistically, cell experiments revealed that IL6 could promote the phosphorylation of ERK1/2 and enhance the expression of transcription factor SP1, thereby promoting AOPE4 expression. The results of this study suggest that coal dust can promote the upregulation of IL6 and AOPE4 in patients, exacerbating cognitive impairment.

Individual and joint exposure to air pollutants and patterns of multiple chronic conditions

Existing research on the detrimental effects of air pollution and its mixture on multiple chronic conditions (MCC) is not yet fully recognized. Our objective was to examine if individual and joint exposure to air pollution is associated with the incidence and patterns of MCC. Totally 10,231 CHARLS 2015 participants aged over 45 years and 1,938 without MCC were followed up in 2018 and 2020. Residential-levelcumulative personal exposure concentrations of PM1, PM10, PM2.5, CO, O3, NO2, SO2, NO3-, Cl-, NH4+, and SO42- at the residential level were determined utilizing a spatio-temporal random forest model with a spatial resolution of 0.1° × 0.1°. In the cross-sectional and longitudinal research, logistic regression, cox regression analysis, and quantile g-computation were utilized to estimate the single and joint effect with MCC and its patterns, respectively. Interaction analyses and stratified analyses were also performed. A correlation was observed between the prevalence of cardiovascular illnesses and the presence of all 11 major air pollutants. PM2.5, PM10, NH4+, NO3-, CO, and SO42- are associated with an increased frequency of respiratory disorders. An increase of PM2.5, PM1, PM10, NO2, and SO2 (a 10 µg/m3 rise), CO (a 0.1 mg/m3 rise), and PMCs (Cl-, NH4+, NO3-, and SO42-) (a 1 µg/m3 rise) corresponded to the HRs (95% CI) for developing MCC of 1.194 (95% CI: 1.043, 1.367), 1.362 (95% CI: 1.073, 1.728), 1.115 (95% CI: 1.026, 1.212), 1.443 (95% CI: 1.151, 1.808), 3.175 (95% CI: 2.291, 4.401), 1.272 (95% CI: 1.149,1.410), 1.382 (95% CI: 1.011, 1.888), 1.107 (95% CI: 1.003, 1.222), 1.035 (95% CI: 0.984, 1.088), and 1.122 (95% CI: 1.086, 1.160), respectively. SO2 was the predominant contributor to the combined effect (HR: 2.083, 95% CI: 1.659-2.508). Gender, age, drinking, and health status could modify the effects of air pollutants on MCC patterns. Long-term exposure to air pollution is correlated to the incidence and patterns of MCC in middle-aged and elderly Chinese individuals. Preventive methods are essential to safeguarding those susceptible to MCC.

Spatial regulation of NMN supplementation on brain lipid metabolism upon subacute and sub-chronic PM exposure in C57BL/6 mice

BACKGROUND

Atmospheric particulate matter (PM) exposure-induced neuroinflammation is critical in mediating nervous system impairment. However, effective intervention is yet to be developed.

RESULTS

In this study, we examine the effect of β-nicotinamide mononucleotide (NMN) supplementation on nervous system damage upon PM exposure and the mechanism of spatial regulation of lipid metabolism. 120 C57BL/6 male mice were exposed to real ambient PM for 11 days (subacute) or 16 weeks (sub-chronic). NMN supplementation boosted the level of nicotinamide adenine dinucleotide (NAD+) in the mouse brain by 2.04 times. This augmentation effectively reduced neuroinflammation, as evidenced by a marked decrease in activated microglia levels across various brain regions, ranging from 29.29 to 85.96%. Whole brain lipidomics analysis revealed that NMN intervention resulted in an less increased levels of ceramide (Cer) and lysophospholipid in the brain following subacute PM exposure, and reversed triglyceride (TG) and glycerophospholipids (GP) following sub-chronic PM exposure, which conferred mice with anti-neuroinflammation response, improved immune function, and enhanced membrane stability. In addition, we demonstrated that the hippocampus and hypothalamus might be the most sensitive brain regions in response to PM exposure and NMN supplementation. Particularly, the alteration of TG (60:10, 56:2, 60:7), diacylglycerol (DG, 42:6), and lysophosphatidylcholine (LPC, 18:3) are the most profound, which correlated with the changes in functional annotation and perturbation of pathways including oxidative stress, inflammation, and membrane instability unveiled by spatial transcriptomic analysis.

CONCLUSIONS

This study demonstrates that NMN intervention effectively reduces neuroinflammation in the hippocampus and hypothalamus after PM exposure by modulating spatial lipid metabolism. Strategies targeting the improvement of lipid homeostasis may provide significant protection against brain injury associated with air pollutant exposure.

Air pollution: a latent key driving force of dementia

Many researchers have studied the role of air pollutants on cognitive function, changes in brain structure, and occurrence of dementia. Due to the wide range of studies and often contradictory results, the present systematic review was conducted to try and clarify the relationship between air pollutants and dementia. To identify studies for this review, a systematic search was conducted in Scopus, PubMed, and Web of Science databases (without historical restrictions) until May 22, 2023. The PECO statement was created to clarify the research question, and articles that did not meet the criteria of this statement were excluded. In this review, animal studies, laboratory studies, books, review articles, conference papers and letters to the editors were avoided. Also, studies focused on the effect of air pollutants on cellular and biochemical changes (without investigating dementia) were also excluded. A quality assessment was done according to the type of design of each article, using the checklist developed by the Joanna Briggs Institute (JBI). Finally, selected studies were reviewed and discussed in terms of Alzheimer's dementia and non-Alzheimer's dementia. We identified 14,924 articles through a systematic search in databases, and after comprehensive reviews, 53 articles were found to be eligible for inclusion in the current systematic review. The results showed that chronic exposure to higher levels of air pollutants was associated with adverse effects on cognitive abilities and the presence of dementia. Studies strongly supported the negative effects of PM2.5 and then NO2 on the brain and the development of neurodegenerative disorders in old age. Because the onset of brain structural changes due to dementia begins decades before the onset of disease symptoms, and that exposure to air pollution is considered a modifiable risk factor, taking preventive measures to reduce air pollution and introducing behavioral interventions to reduce people's exposure to pollutants is advisable.

Effect of air pollutants particulate matter (PM2.5, PM10), sulfur dioxide (SO2) and ozone (O3) on cognitive health

Impaired cognitive health is the leading cause of various disabilities and disorders. Air pollution has been dramatically increasing over the last few decades and has been identified as a potential risk factor for impaired cognitive health. This study investigates the effect of air pollutants, particulate matter (PM2.5, PM10), sulfur dioxide (SO2), and ground-level ozone, on global cognitive health. The data on environmental pollutants and cognitive health were recorded from PubMed, Web of Science, Scopus, and Google Scholar. Initially, 790 articles were identified after screening for duplicates and applying the inclusion and exclusion criteria, 21 studies were included, and data was synthesized to get a pooled result. The overall results revealed that increased exposure to PM2.5 was positively and significantly associated with cognitive decline (OR 1.49; 95% CI 1.11, 1.99; p = 0.01). The risk of cognitive impairment due to PM10 (OR 1.30; 95% CI 1.00-1.70, p = 0.05), and SO2 (OR 1.39; 95% CI 1.27-1.51; p < 0.01) exposure were also significantly heightened. The study findings show that overall exposure to particulate matter PM2.5, PM10, and SO2 was associated with an increased risk of a decrease in global cognitive functions. The findings suggest that reducing levels of air pollutants could be a strategic approach to mitigate cognitive health risks in populations worldwide.

Mechanistic Approach to Immunity and Immunotherapy of Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a debilitating neurodegenerative condition characterized by progressive cognitive decline and memory loss, affecting millions of people worldwide. Traditional treatments, such as cholinesterase inhibitors and NMDA receptor antagonists, offer limited symptomatic relief without addressing the underlying disease mechanisms. These limitations have driven the development of more potent and effective therapies. Recent advances in immunotherapy present promising avenues for AD treatment. Immunotherapy strategies, including both active and passive approaches, harness the immune system to target and mitigate AD-related pathology. Active immunotherapy stimulates the patient's immune response to produce antibodies against AD-specific antigens, while passive immunotherapy involves administering preformed antibodies or immune cells that specifically target amyloid-β (Aβ) or tau proteins. Monoclonal antibodies, such as aducanumab and lecanemab, have shown potential in reducing Aβ plaques and slowing cognitive decline in clinical trials, despite challenges related to adverse immune responses and the need for precise targeting. This comprehensive review explores the role of the immune system in AD, evaluates the current successes and limitations of immunotherapeutic approaches, and discusses future directions for enhancing the treatment efficacy.

How does urbanization affect the cognitive function among older adults: A geospatial analysis in China

There has been a plethora of studies on urbanization and older adults, and more recent ones on how older adults adapt to this process with their cognitive competence. Yet it has been unclear about the relationship between them, like how the level and rate of urbanization affect the cognitive function among older adults. This study sourced, formed, and analyzed a set of geospatial big datasets from different sources, such as the Chinese Longitudinal Healthy Longevity Survey (CLHLS) data, and the NPP/VIIRS nighttime light (NTL) data. Results showed a generally negative linear association between the rate of urbanization and cognitive performance among older adults in China. The "U" shaped non-linear relationship between urbanization level and cognitive function, as well as the tipping point, were identified. At the same time, it should be noted that mediators such as education, physical activity, social activity, and community elderly service might be able to mitigate these negative associations. Furthermore, older adults living in eastern regions or urban areas appeared to have better cognitive function than those living in mid-western regions or rural areas in China. The findings also pointed to the importance of focusing on older adults with poor cognitive health status in rapidly urbanizing areas.

The Association between Exposure to Fine Particulate Matter and MRI-Assessed Locus Coeruleus Integrity in the Vietnam Era Twin Study of Aging (VETSA)

BACKGROUND

Increased exposure to ambient air pollution, especially fine particulate matter ≤ 2.5 μ m (PM 2.5 ) is associated with poorer brain health and increased risk for Alzheimer's disease (AD) and related dementias. The locus coeruleus (LC), located in the brainstem, is one of the earliest regions affected by tau pathology seen in AD. Its diffuse projections throughout the brain include afferents to olfactory areas that are hypothesized conduits of cerebral particle deposition. Additionally, extensive contact of the LC with the cerebrovascular system may present an additional route of exposure to environmental toxicants.

OBJECTIVE

Our aim was to investigate if exposure to PM 2.5 was associated with LC integrity in a nationwide sample of men in early old age, potentially representing one pathway through which air pollution can contribute to increased risk for AD dementia.

METHODS

We examined the relationship between PM 2.5 and in vivo magnetic resonance imaging (MRI) estimates of LC structural integrity indexed by contrast to noise ratio (LC CNR ) in 381 men [mean age = 67.3 ; standard deviation ( SD ) = 2.6 ] from the Vietnam Era Twin Study of Aging (VETSA). Exposure to PM 2.5 was taken as a 3-year average over the most recent period for which data were available (average of 5.6 years prior to the MRI scan). We focused on LC CNR in the rostral-middle portion of LC due to its stronger associations with aging and AD than the caudal LC. Associations between PM 2.5 exposures and LC integrity were tested using linear mixed effects models adjusted for age, scanner, education, household income, and interval between exposure and MRI. A co-twin control analysis was also performed to investigate whether associations remained after controlling for genetic confounding and rearing environment.

RESULTS

Multiple linear regressions revealed a significant association between PM 2.5 and rostral-middle LC CNR (β = - 0.16 ; p = 0.02 ), whereby higher exposure to PM 2.5 was associated with lower LC CNR . A co-twin control analysis found that, within monozygotic pairs, individuals with higher PM 2.5 exposure showed lower LC CNR (β = - 0.11 ; p = 0.02 ), indicating associations were not driven by genetic or shared environmental confounds. There were no associations between PM 2.5 and caudal LC CNR or hippocampal volume, suggesting a degree of specificity to the rostral-middle portion of the LC.

DISCUSSION

Given previous findings that loss of LC integrity is associated with increased accumulation of AD-related amyloid and tau pathology, impacts on LC integrity may represent a potential pathway through which exposure to air pollution increases AD risk. https://doi.org/10.1289/EHP14344.

HO-1 upregulation promotes mitophagy-dependent ferroptosis in PM2.5-exposed hippocampal neurons

Fine particulate matter (PM2.5) has been extensively implicated in the pathogenesis of neurodevelopmental disorders, but the underlying mechanism remains unclear. Recent studies have revealed that PM2.5 plays a role in regulating iron metabolism and redox homeostasis in the brain, which is closely associated with ferroptosis. In this study, the role and underlying mechanism of ferroptosis in PM2.5-induced neurotoxicity were investigated in mice, primary hippocampal neurons, and HT22 cells. Our findings demonstrated that exposure to PM2.5 could induce abnormal behaviors, neuroinflammation, and neuronal loss in the hippocampus of mice. These effects may be attributed to ferroptosis induced by PM2.5 exposure in hippocampal neurons. RNA-seq analysis revealed that the upregulation of iron metabolism-related protein Heme Oxygenase 1 (HO-1) and the activation of mitophagy might play key roles in PM2.5-induced ferroptosis in HT22 cells. Subsequent in vitro experiments showed that PM2.5 exposure significantly upregulated HO-1 in primary hippocampal neurons and HT22 cells. Moreover, PM2.5 exposure activated mitophagy in HT22 cells, leading to the loss of mitochondrial membrane potential, alterations in the expression of autophagy-related proteins LC3, P62, and mTOR, as well as an increase in mitophagy-related protein PINK1 and PARKIN. As a heme-degradation enzyme, the upregulation of HO-1 promotes the release of excess iron, genetically inhibiting the upregulation of HO-1 in HT22 cells could prevent both PM2.5-induced mitophagy and ferroptosis. Furthermore, pharmacological inhibition of mitophagy in HT22 cells reduced levels of ferrous ions and lipid peroxides, thereby preventing ferroptosis. Collectively, this study demonstrates that HO-1 mediates PM2.5-induced mitophagy-dependent ferroptosis in hippocampal neurons, and inhibiting mitophagy or ferroptosis may be a key therapeutic target to ameliorate neurotoxicity following PM2.5 exposure.

Causal association between particulate matter 2.5 and Alzheimer's disease: a Mendelian randomization study

Background

Although epidemiological evidence implies a link between exposure to particulate matter (PM) and Alzheimer's disease (AD), establishing causality remains a complex endeavor. In the present study, we used Mendelian randomization (MR) as a robust analytical approach to explore the potential causal relationship between PM exposure and AD risk. We also explored the potential associations between PM exposure and other neurodegenerative diseases.

Methods

Drawing on extensive genome-wide association studies related to PM exposure, we identified the instrumental variables linked to individual susceptibility to PM. Using summary statistics from five distinct neurodegenerative diseases, we conducted two-sample MR analyses to gauge the causal impact of PM on the risk of developing these diseases. Sensitivity analyses were undertaken to evaluate the robustness of our findings. Additionally, we executed multivariable MR (MVMR) to validate the significant causal associations identified in the two-sample MR analyses, by adjusting for potential confounding risk factors.

Results

Our MR analysis identified a notable association between genetically predicted PM2.5 (PM with a diameter of 2.5 μm or less) exposure and an elevated risk of AD (odds ratio, 2.160; 95% confidence interval, 1.481 to 3.149; p < 0.001). A sensitivity analysis supported the robustness of the observed association, thus alleviating concerns related to pleiotropy. No discernible causal relationship was identified between PM and any other neurodegenerative diseases. MVMR analyses-adjusting for smoking, alcohol use, education, stroke, hearing loss, depression, and hypertension-confirmed a persistent causal relationship between PM2.5 and AD. Sensitivity analyses, including MR-Egger and weighted median analyses, also supported this causal association.

Conclusion

The present MR study provides evidence to support a plausible causal connection between PM2.5 exposure and AD. The results emphasize the importance of contemplating air quality interventions as a public health strategy for reducing AD risk.

Long-term exposure to fine particulate matter constituents and cognitive impairment among older adults: An 18-year Chinese nationwide cohort study

BACKGROUND

Although growing evidence has shown independent links of long-term exposure to fine particulate matter (PM2.5) with cognitive impairment, the effects of its constituents remain unclear. This study aims to explore the associations of long-term exposure to ambient PM2.5 constituents' mixture with cognitive impairment in Chinese older adults, and to further identify the main contributor.

METHODS

15,274 adults ≥ 65 years old were recruited by the Chinese Longitudinal Healthy Longevity Study (CLHLS) and followed up through 7 waves during 2000-2018. Concentrations of ambient PM2.5 and its constituents (i.e., black carbon [BC], organic matter [OM], ammonium [NH4+], sulfate [SO42-], and nitrate [NO3-]) were estimated by satellite retrievals and machine learning models. Quantile-based g-computation model was employed to assess the joint effects of a mixture of 5 PM2.5 constituents and their relative contributions to cognitive impairment. Analyses stratified by age group, sex, residence (urban vs. rural), and region (north vs. south) were performed to identify vulnerable populations.

RESULTS

During the average 3.03 follow-up visits (89,296.9 person-years), 4294 (28.1%) participants had developed cognitive impairment. The adjusted hazard ratio [HR] (95% confidence interval [CI]) for cognitive impairment for every quartile increase in mixture exposure to 5 PM2.5 constituents was 1.08 (1.05-1.11). BC held the largest index weight (0.69) in the positive direction in the qg-computation model, followed by OM (0.31). Subgroup analyses suggested stronger associations in younger old adults and rural residents.

CONCLUSION

Long-term exposure to ambient PM2.5, particularly its constituents BC and OM, is associated with an elevated risk of cognitive impairment onset among Chinese older adults.

PM2.5 exposure exacerbates seizure symptoms and cognitive dysfunction by disrupting iron metabolism and the Nrf2-mediated ferroptosis pathway

In recent years, air pollution has garnered global attention due to its ability to traverse borders and regions, thereby impacting areas far removed from the emission sources. While prior studies predominantly focused on the deleterious effects of PM2.5 on the respiratory and cardiovascular systems, emerging evidence has highlighted the potential risks of PM2.5 exposure to the central nervous system. Nonetheless, research elucidating the potential influences of PM2.5 exposure on seizures, specifically in relation to neuronal ferroptosis, remains limited. In this study, we investigated the potential effects of PM2.5 exposure on seizure symptoms and seizures-induced hippocampal neuronal ferroptosis. Our findings suggest that seizure patients residing in regions with high PM2.5 levels are more likely to disturb iron homeostasis and the Nrf2 dependent ferroptosis pathway compared to those living in areas with lower PM2.5 levels. The Morris Water Maze test, Racine scores, and EEG recordings in epileptic mice suggest that PM2.5 exposure can exacerbate seizure symptoms and cognitive dysfunction. Neurotoxic effects of PM2.5 exposure were demonstrated via Nissl staining and CCK-8 assays. Direct evidence of PM2.5-induced hippocampal neuronal ferroptosis was provided through TEM images. Additionally, increased Fe2+ and lipid ROS levels indirectly supported the notion of PM2.5-induced hippocampal ferroptosis. Therefore, our study underscores the necessity of preventing and controlling PM2.5 levels, particularly for patients with seizures.

Severer air pollution, poorer cognitive function: Findings from 176,345 elders in Northwestern China

BACKGROUND

Limited evidence exists regarding the link between air pollution exposure and cognitive function in developing countries, particularly in areas with abundant natural sources of particulate matter.

OBJECTIVES

To investigate this association in a large representative sample of the elderly in northwestern China.

METHODS

We performed a cross-sectional study among 176,345 participants aged 60-100 years in northwestern China in 2020. A satellite-based spatiotemporal model was applied to assess three-year annual averages of particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5), ≤ 10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) at residential address. Poor cognitive function was assessed using the Mini-Mental State Examination (MMSE). Generalized linear mixed models were used to assess associations.

RESULTS

Compared with participants with the lowest quartiles of PM2.5, PM10, and O3 levels, those with the second, third, and highest quartiles of air pollutants consistently showed increased odds of poor cognitive function and decreased MMSE scores. The odds ratios of poor cognitive function associated with a 10 μg/m3 increment in PM2.5, PM10, and O3 were 1.26 (95 % confidence interval [CI]: 1.17, 1.36), 1.06 (95 %CI: 1.04, 1.08), and 2.76 (95 %CI: 2.11, 3.62), respectively. Subgroup analyses suggested stronger associations between air pollution exposures and poor cognitive function among participants who were younger, were non-Uyghur and were physically active.

CONCLUSION

Long-term exposures to PM2.5, PM10 and O3 were associated with poor cognitive function in elders. Our results suggest that reducing air pollution may alleviate the burden of poor cognitive function in the elderly.

Association Between Long-Term Exposure to Ambient Air Pollution and the Risk of Mild Cognitive Impairment in a Chinese Urban Area: A Case-Control Study

Background

As a prodromal stage of dementia, significant emphasis has been placed on the identification of modifiable risks of mild cognitive impairment (MCI). Research has indicated a correlation between exposure to air pollution and cognitive function in older adults. However, few studies have examined such an association among the MCI population inChina.

Objective

We aimed to explore the association between air pollution exposure and MCI risk from the Hubei Memory and Aging Cohort Study.

Methods

We measured four pollutants from 2015 to 2018, 3 years before the cognitive assessment of the participants. Logistic regression models were employed to calculate odds ratios (ORs) to assess the relationship between air pollutants and MCI risk.

Results

Among 4,205 older participants, the adjusted ORs of MCI risk for the highest quartile of PM2.5, PM10, O3, and SO2 were 1.90 (1.39, 2.62), 1.77 (1.28, 2.47), 0.56 (0.42, 0.75), and 1.18 (0.87, 1.61) respectively, compared with the lowest quartile. Stratified analyses indicated that such associations were found in both males and females, but were more significant in older participants.

Conclusions

Our findings are consistent with the growing evidence suggesting that air pollution increases the risk of mild cognitive decline, which has considerable guiding significance for early intervention of dementia in the older population. Further studies in other populations and broader geographical areas are warranted to validate these findings.

Long-Term PM2.5 Exposure, Lung Function, and Cognitive Function Among Middle-Aged and Older Adults in China

BACKGROUND

Long-term exposure to PM2.5 is related to poor lung function and cognitive impairment, but less is known about the pathway involved in this association. We aimed to explore whether the effect of PM2.5 on cognitive function was mediated by lung function.

METHODS

A total of 7 915 adults older than 45 years old were derived from the China Health and Retirement Longitudinal Study (CHARLS) collected in 2011 and 2015. PM2.5 exposure was estimated using a geographically weighted regression model. Lung function was measured by peak expiratory flow (PEF). Cognitive function was evaluated through a structured questionnaire with 4 dimensions: episodic memory, attention, orientation, and visuoconstruction. Under the counterfactual framework, causal mediation analysis was applied to examine direct and indirect associations.

RESULTS

An interquartile range (IQR) increase in PM2.5 change was significantly related to an 8.480 (95% confidence interval [CI]: 3.116, 13.845) decrease in PEF change and a 0.301 (95% CI: 0.100, 0.575) decrease in global cognitive score change. The direct and indirect effects of PM2.5 exposure on global cognitive performance were -0.279 (95% CI: -0.551, -0.060) and -0.023 (95% CI: -0.041, -0.010), respectively. The proportion of the indirect effect was 7.48% (p = .010). The same significant association appeared in only 2 dimensions, episodic memory and attention, which were both mediated by PEF.

CONCLUSIONS

Lung function played a partially mediating role in the association between long-term PM2.5 exposure and cognition. More clean air actions should be undertaken to improve lung function and cognitive function in older adults.

Alzheimer's Related Neurodegeneration Mediates Air Pollution Effects on Medial Temporal Lobe Atrophy

Exposure to ambient air pollution, especially particulate matter with aerodynamic diameter <2.5 μm (PM2.5) and nitrogen dioxide (NO2), are environmental risk factors for Alzheimer's disease and related dementia. The medial temporal lobe (MTL) is an important brain region subserving episodic memory that atrophies with age, during the Alzheimer's disease continuum, and is vulnerable to the effects of cerebrovascular disease. Despite the importance of air pollution it is unclear whether exposure leads to atrophy of the MTL and by what pathways. Here we conducted a longitudinal study examining associations between ambient air pollution exposure and MTL atrophy and whether putative air pollution exposure effects resembled Alzheimer's disease-related neurodegeneration or cerebrovascular disease-related neurodegeneration. Participants included older women (n = 627; aged 71-87) who underwent two structural brain MRI scans (MRI-1: 2005-6; MRI-2: 2009-10) as part of the Women's Health Initiative Memory Study of Magnetic Resonance Imaging. Regionalized universal kriging was used to estimate annual concentrations of PM2.5 and NO2 at residential locations aggregated to 3-year averages prior to MRI-1. The outcome was 5-year standardized change in MTL volumes. Mediators included voxel-based MRI measures of the spatial pattern of neurodegeneration of Alzheimer's disease (Alzheimer's disease pattern similarity scores [AD-PS]) and whole-brain white matter small-vessel ischemic disease (WM-SVID) volume as a proxy of global cerebrovascular damage. Structural equation models were constructed to examine whether the associations between exposures with MTL atrophy were mediated by the initial level or concurrent change in AD-PS score or WM-SVID while adjusting for sociodemographic, lifestyle, clinical characteristics, and intracranial volume. Living in locations with higher PM2.5 (per interquartile range [IQR]=3.17μg/m3) or NO2 (per IQR=6.63ppb) was associated with greater MTL atrophy (βPM2.5 = -0.29, 95% confidence interval [CI]=[-0.41,-0.18]; βNO2 =-0.12, 95%CI=[-0.23,-0.02]). Greater PM2.5 was associated with larger increases in AD-PS (βPM2.5 = 0.23, 95%CI=[0.12,0.33]) over time, which partially mediated associations with MTL atrophy (indirect effect= -0.10; 95%CI=[-0.15, -0.05]), explaining approximately 32% of the total effect. NO2 was positively associated with AD-PS at MRI-1 (βNO2=0.13, 95%CI=[0.03,0.24]), which partially mediated the association with MTL atrophy (indirect effect= -0.01, 95% CI=[-0.03,-0.001]). Global WM-SVID at MRI-1 or concurrent change were not significant mediators between exposures and MTL atrophy. Findings support the mediating role of Alzheimer's disease-related neurodegeneration contributing to MTL atrophy associated with late-life exposures to air pollutants. Alzheimer's disease-related neurodegeneration only partially explained associations between exposure and MTL atrophy suggesting the role of multiple neuropathological processes underlying air pollution neurotoxicity on brain aging.

Particulate matter exposure and neurodegenerative diseases: A comprehensive update on toxicity and mechanisms

Exposure to particulate matter (PM) has been associated with a range of health impacts, including neurological abnormalities that affect neurodevelopment, neuroplasticity, and behavior. Recently, there has been growing interest in investigating the possible relationship between PM exposure and the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. However, the precise mechanism by which PM affects neurodegeneration is still unclear, even though several epidemiological and animal model studies have provided mechanistic insights. This article presents a review of the current research on the neurotoxicity of PM and its impact on neurodegenerative diseases. This review summarizes findings from epidemiological and animal model studies collected through searches in Google Scholar, PubMed, Web of Science, and Scopus. This review paper also discusses the reported effects of PM exposure on the central nervous system and highlights research gaps and future directions. The information presented in this review may inform public health policies aimed at reducing PM exposure and may contribute to the development of new treatments for neurodegenerative diseases. Further mechanistic and therapeutic research will be needed to fully understand the relationship between PM exposure and neurodegenerative diseases.

Addressing Global Environmental Challenges to Mental Health Using Population Neuroscience: A Review

Importance

Climate change, pollution, urbanization, socioeconomic inequality, and psychosocial effects of the COVID-19 pandemic have caused massive changes in environmental conditions that affect brain health during the life span, both on a population level as well as on the level of the individual. How these environmental factors influence the brain, behavior, and mental illness is not well known.

Observations

A research strategy enabling population neuroscience to contribute to identify brain mechanisms underlying environment-related mental illness by leveraging innovative enrichment tools for data federation, geospatial observation, climate and pollution measures, digital health, and novel data integration techniques is described. This strategy can inform innovative treatments that target causal cognitive and molecular mechanisms of mental illness related to the environment. An example is presented of the environMENTAL Project that is leveraging federated cohort data of over 1.5 million European citizens and patients enriched with deep phenotyping data from large-scale behavioral neuroimaging cohorts to identify brain mechanisms related to environmental adversity underlying symptoms of depression, anxiety, stress, and substance misuse.

Conclusions and Relevance

This research will lead to the development of objective biomarkers and evidence-based interventions that will significantly improve outcomes of environment-related mental illness.

Air Quality, Pollution Perception, and Residents' Health: Evidence from China

Environmental and resident health issues associated with air pollution are an area of growing concern for both policy officials and the general public. In recent years, China has been accelerating the construction of a Beautiful China and a Healthy China, with the aim of protecting and improving the environment and ensuring public health. In this study, we aimed to explore the impact of air quality and air pollution perception on residents' health. This study used the 2017 Chinese General Social Survey data to measure self-rated health, mental health, and air pollution perception. Using matched socioeconomic indicators and air pollution data, we analyzed the relationship between subjective perception of air pollution, objective air pollution data, and residents' health. The results showed the following: (1) Air pollution perception has a significant negative impact on self-rated health and mental health. Thus, it needs more consideration to reduce environmental health risks. (2) Objective air pollution has a significant negative impact on mental health. At the same time, its effect on self-rated health was insignificant. These results provide empirical evidence supporting the Chinese government's decision to invest more in combating air pollution and ensuring the health of Chinese residents.

Alzheimer's disease-like cortical atrophy mediates the effect of air pollution on global cognitive function

Little is known about the effect of air pollution on Alzheimer's disease (AD)-specific brain structural pathologies. There is also a lack of evidence on whether this effect leads to poorer cognitive function. We investigated whether, and the extent to which, AD-like cortical atrophy mediated the association between air pollution exposures and cognitive function in dementia-free adults. We used cross-sectional data from 640 participants who underwent brain magnetic resonance imaging and the Montreal Cognitive Assessment (MoCA). Mean cortical thickness (as the measure of global cortical atrophy) and machine learning-based AD-like cortical atrophy score were estimated from brain images. Concentrations of particulate matter with diameters ≤ 10 μm (PM₁₀) and ≤ 2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) were estimated based on each participant's residential address. Following the product method, a mediation effect was tested by conducting a series of three regression analyses (exposure to outcome; exposure to mediator; and exposure and mediator to outcome). A 10 μg/m³ increase in PM₁₀ (β = -1.13; 95 % CI, -1.73 to -0.53) and a 10 ppb increase in NO₂ (β = -1.09; 95 % CI, -1.40 to -0.78) were significantly associated with a lower MoCA score. PM₁₀ (β = 0.27; 95 % CI, 0.06 to 0.48) and NO₂ (β = 0.35; 95 % CI, 0.25 to 0.45) were significantly associated with an increased AD-like cortical atrophy score. Effects of PM₁₀ and NO₂ on MoCA scores were significantly mediated by mean cortical thickness (proportions mediated: 25 %-28 %) and AD-like cortical atrophy scores (13 %-16 %). The findings suggest that air pollution exposures may induce AD-like cortical atrophy, and that this effect may lead to poorer cognitive function in dementia-free adults.

Associations between PM2.5 exposure and Alzheimer's Disease prevalence Among elderly in eastern China

BACKGROUND

Studies showed that PM_2.5 might be associated with various neurogenic diseases such as Alzheimer's Disease (AD). However, this topic had been little studied in Zhejiang province of China.  METHODS: In 2018, we established a cohort of AD high-risk population with 1,742 elderly aged 60 and above. In 2020, the cohort was followed up, a total of 1,545 people participated the 2 surveys. Data collection included questionnaires and basic physical examinations. The average residential exposure to PM_2.5 for each participant, that in a 5-years period prior to the first survey, was estimated using a satellite-based spatial statistical model. We determined the association between PM_2.5 and AD prevalence by cox proportional hazards regression model.  RESULTS: This study showed that an increase in the PM_2.5 level was an important associated risk factor that contributed to AD. The average PM_2.5 exposure levels among the study population ranged from 32.69 μg/m³ to 39.67 μg/m³ from 2013 to 2017, which were much higher than 5 μg/m³ that specified in the WHO air quality guidelines. There was an association between PM_2.5 exposure and AD, and the correlations between PM_2.5 and Mini-Mental State Examination, Montreal cognitive assessment scale scores were statistically significant. An increase in the PM_2.5 level by 10 μg/m³ elevated the risk of AD among residents by 2%-5% (HR _{model 2-model 4} = 1.02 to 1.05, CI _{model 2-model 4} = 1.01-1.10). The subgroups of male, with old age, with low education levels, used to work as farmers or blue-collar workers before retirement, overweight and obese were associated with a higher effect of PM_2.5.

CONCLUSIONS

Reducing PM_2.5 exposure might be a good way to prevent AD.

Association between air pollution and CSF sTREM2 in cognitively normal older adults: The CABLE study

Objectives

Ambient air pollution aggravates the process of Alzheimer's disease (AD) pathology. Currently, the exact inflammatory mechanisms underlying these links from clinical research remain largely unclear.

Methods

This study included 1,131 cognitively intact individuals from the Chinese Alzheimer's Biomarker and LifestylE database with data provided on cerebrospinal fluid (CSF) AD biomarkers (amyloid beta‐peptide 42 [Aβ42], total tau [t‐tau], and phosphorylated tau [p‐tau]), neuroinflammatory (CSF sTREM2), and systemic inflammatory markers (high sensitivity C‐reactive protein and peripheral immune cells). The 2‐year averaged levels of ambient fine particulate matter with diameter <2.5 μm (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) were estimated at each participant's residence. Multiple‐adjusted models were approached to detect associations of air pollution with inflammatory markers and AD‐related proteins.

Results

Ambient 2‐year averaged exposure of PM_2.5 was associated with changes of neuroinflammatory markers, that is, CSF sTREM2 (β = −0.116, p = 0.0002). Similar results were found for O₃ exposure among the elderly (β = −0.111, p = 0.0280) or urban population (β = −0.090, p = 0.0144). No significant evidence supported NO₂ related to CSF sTREM2. For potentially causal associations with accumulated AD pathologies, the total effects of PM_2.5 on CSF amyloid‐related protein (CSF Aβ42 and p‐tau/Aβ42) were partly mediated by CSF sTREM2, with proportions of 14.22% and 47.15%, respectively. Additional analyses found inverse associations between peripheral inflammatory markers with PM_2.5 and NO₂, but a positive correlation with O₃.

Interpretation

These findings demonstrated a strong link between PM_2.5 exposure and microglial dysfunction. Furthermore, CSF sTREM2 as a key mediator modulated the influences of PM_2.5 exposure on AD amyloid pathologies.