Are noise and air pollution related to the incidence of dementia? A cohort study in London, England

[Psyche in Climate Crisis? An Update on Ecological Psychiatry and Psychotherapy]

The human-caused climate crisis is advancing relentlessly and poses a global threat. But to what extent is our psyche also in crisis due to climate change? This article explores the profound impacts of the climate crisis and environmental destruction on mental health, advocating for a comprehensive, ecologically-oriented approach to psychiatry and psychotherapy.

A systematic review with a Burden of Proof meta-analysis of health effects of long-term ambient fine particulate matter (PM2.5) exposure on dementia

Previous studies have indicated increased dementia risk associated with fine particulate matter (PM2.5) exposure; however, the findings are inconsistent. In this systematic review, we assessed the association between long-term PM2.5 exposure and dementia outcomes using the Burden of Proof meta-analytic framework, which relaxes log-linear assumptions to better characterize relative risk functions and quantify unexplained between-study heterogeneity (PROSPERO, ID CRD42023421869). Here we report a meta-analysis of 28 longitudinal cohort studies published up to June 2023 that investigated long-term PM2.5 exposure and dementia outcomes. We derived risk-outcome scores (ROSs), highly conservative measures of effect size and evidence strength, mapped onto a 1-5-star rating from 'weak and/or inconsistent evidence' to 'very strong and/or consistent evidence'. We identified a significant nonlinear relationship between PM2.5 exposure and dementia, with a minimum 14% increased risk averaged across PM2.5 levels between 4.5 and 26.9 µg m-3 (the 15th to 85th percentile exposure range across included studies), relative to a reference of 2.0 µg m-3 (n = 49, ROS = 0.13, two stars). We found a significant association of PM2.5 with Alzheimer's disease (n = 12, ROS = 0.32, three stars) but not with vascular dementia. Our findings highlight the potential impact of air pollution on brain aging.

The causal links between long-term exposure to major chemical components of PM2.5 and overall outpatient visits in mainland China: A nationwide study in the difference-in-differences framework

INTRODUCTION

Although the adverse health effects of PM2.5 exposure has been well documented, evidence of its adverse effect on overall outpatient visits was still limited. Besides, the adverse health effects of PM2.5 exposure get complicated due to various components within the particles. So far, little is known about the relationship between PM2.5 components and overall outpatient visits.

OBJECTIVES

This study aims to evaluate the causal relationships between long-term exposure to primary chemical components of PM2.5 and outpatient visits, while estimating the mixture effect and relative contribution of the components.

METHODS

Based on nationwide provincial-level surveillance data of outpatient visits in China and well-validated simulations of PM2.5 components concentration, we employed the Difference-In-Differences (DID) approach to evaluate the causal relationships between long-term exposure to primary chemical components of PM2.5 and outpatient visits, and used a Bayesian Weighted Quantile Sum (BWQS) regression to assess the mixture effect of the components.

RESULTS

We found a 20.44% increase in the risk (IR%) of outpatient visits following each InterQuartile Range (IQR) increment in PM2.5 concentration. Our estimation further suggested a 17.07%, 15.91%, and 14.04% increase in the risk of outpatient visits for organic matter, sulfate, and nitrate, but non-significant increases for other components. However, when considering the inter-components correlation, sulfate and black carbon contributed most (42.3% and 28.1%, respectively) to the overall mixture effect of PM2.5 which was indicated by a 4.84% increase (95%CI: 1.92%, 7.83%) in the risk of outpatient visits following every unit increase in the overall BWQS index. Additionally, stratified analyses showed a stronger association among aged provinces and provinces with lower education rates.

CONCLUSION

Our findings would improve understanding of the individual and mixture impact of major chemical components of PM2.5 and may contribute to more targeted and optimized environmental programs for pollution control.

Whole-brain gray matter volume and fractional anisotropy of the posterior thalamic radiation and sagittal stratum in healthy adults correlate with the local environment

The impacts of air pollution, local climate, and urbanization on human health have been well-documented in recent studies. In this study, we combined magnetic resonance imaging (MRI) brain analysis with a questionnaire survey on the local environment in 141 healthy middle-aged men and women. Our findings reveal that a favorable environment is positively correlated with gray matter volume (GMV) in the frontal and occipital lobes, cerebellum, and whole brain, as well as with fractional anisotropy (FA) in the fornix (including the fornix stria terminalis), posterior thalamic radiation (PTR), sagittal stratum (SS), and whole brain. Among these, significant correlations between the local environment and whole-brain and cerebellar GMV, PTR, and SS FA remained after Bonferroni correction. Additionally, the positive relationship between the local environment and whole-brain GMV was further supported by principal component analysis (PCA). This is the first study to demonstrate that healthy adult brain structure, as indicated by GMV and FA values, can be influenced by the local environment.

Ambient Air Pollution and Parkinson's Disease and Alzheimer's Disease: An Updated Meta-Analysis

BACKGROUND

Previous epidemiological evidence regarding the associations between ambient air pollution and two major neurodegenerative diseases, Alzheimer's disease (AD) and Parkinson's disease (PD), remains inconclusive.

OBJECTIVE

This study aimed to evaluate the associations between long-term and short-term exposure to PM2.5 and PM10 (i.e., particulate matter with an aerodynamic diameter of, or smaller than, 2.5 μm or 10 μm), nitrogen dioxide (NO2), ozone, sulfur dioxide, and carbon monoxide and the risks of AD and PD.

METHODS

A random-effects model was used to summarize individual effect estimates in the meta-analysis. A subgroup meta-analysis was further conducted to explore the potential sources of heterogeneity.

RESULTS

In total, 42 eligible studies were included. For each 5 μg/m3 increase in long-term PM2.5 exposure, the odds ratios (ORs) were 1.16 (95% CI: 1.04, 1.30; I2 = 95%) and 1.10 (95% CI: 1.03, 1.17; I2 = 95%) for AD and PD, respectively. For each 5 μg/m3 increase in short-term PM2.5 exposure, the OR was 1.01 (95% CI: 1.002, 1.01; I2 = 77%) for PD. For each 1 ppb increase in long-term NO2 exposure, the OR was 1.01 (95% CI: 1.0002, 1.02; I2 = 79%) for PD.

CONCLUSION

Ambient air pollution, particularly PM2.5, may contribute to the increased risks of neurodegenerative diseases including AD and PD.

The impacts of air pollution on mortality and hospital readmission among Medicare beneficiaries with Alzheimer's disease and Alzheimer's disease-related dementias: a national retrospective cohort study in the USA

BACKGROUND

Alzheimer's disease and Alzheimer's disease-related dementias (AD/ADRD) are prevalent neurodegenerative disorders, posing a critical worldwide public health challenge. Ambient air pollution has been identified as a potential risk factor for AD progression based on toxicological and epidemiological studies. We aimed to evaluate the impacts of air pollution-including fine particulate matter (PM2·5), nitrogen dioxide (NO2), summer ozone (O3), and oxidant-on readmission or death among Medicare enrollees previously hospitalised with an AD/ADRD diagnosis code.

METHODS

We constructed a population-based nationwide retrospective cohort including all Medicare fee-for-service beneficiaries (aged ≥65 years) in the contiguous USA (2000-16) hospitalised with AD/ADRD, and followed them up from the year after their first hospitalisation until (1) year of death (mortality cohort) and (2) year of second hospitalisation for any cause (readmission cohort). We calculated annual average PM2·5, NO2, summer O3, and oxidant concentrations for each individual at their residential ZIP code in each year after their first hospitalisation with AD/ADRD. We applied Cox proportional hazard models for the mortality and readmission cohorts stratifying on individual risk factors and adjusting for socioeconomic status, seasonal temperatures, and relative humidity.

FINDINGS

Our cohort consisted of 5 544 118 individuals, of whom 4 543 759 (82·0%) died and 3 880 894 (70·0%) were readmitted to the hospital during the study period. The average follow-up times were 3·34 years (SD 2·60) for the mortality cohort and 1·98 years (SD 1·65) for the readmission cohort. In both the mortality and readmission cohorts we found significant associations with each pollutant. For an IQR increase in NO2, we found a hazard ratio (HR) for mortality of 1·012 (95% CI 1·009-1·015) and an HR for readmission of 1·110 (1·104-1·117). In the readmission cohort, we found an HR of 1·084 (1·079-1·089) for an IQR increase (3·87 μg/m3) in PM2·5. The results slightly decreased in multi-pollutant models. The results of effect modification for mortality and readmission varied by pollutant, but higher risks were found among Black males and among those eligible for Medicaid in general.

INTERPRETATION

We provide new evidence that among a susceptible population with previous AD/ADRD-related hospitalisations, annual air pollution exposure since first hospitalisation is associated with risk of readmission and death.

FUNDING

National Institute on Aging.

Machine learning identifies routine blood tests as accurate predictive measures of pollution-dependent poor cognitive function

Background

Several modifiable risk factors for dementia and related neurodegenerative diseases have been identified including education level, socio-economic status, and environmental exposures - however, how these population-level risks relate to individual risk remains elusive. To address this, we assess over 450 potential risk factors in one deeply clinically and demographically phenotyped cohort using random forest classifiers to determine predictive markers of poor cognitive function. This study aims to understand early risk factors for dementia by identifying predictors of poor cognitive performance amongst a comprehensive battery of imaging, blood, atmospheric pollutant and socio-economic measures.

Methods

Random forest modelling was used to determine significant predictors of poor cognitive performance in a cohort of 324 individuals (age 61.6 ± 4.8 years; 150 males, 174 females) without extant neurological disease. 457 features were assessed including brain imaging measures of volume and iron deposition, blood measures of anaemia, inflammation, and heavy metal levels, social deprivation indicators and atmospheric pollution exposure.

Results

Routinely assessed markers of anaemia including mean corpuscular haemoglobin concentration were identified as robust predictors of poor general cognition, where both extremes (low and high) were associated with poor cognitive performance. The strongest, most consistent predictors of poor cognitive performance were environmental measures of atmospheric pollution, in particular, lead, carbon monoxide, and particulate matter. Feature analysis demonstrated a significant negative relationship between low mean corpuscular haemoglobin concentration and high levels of atmospheric pollutants highlighting the potential of routinely assessed blood tests as a predictive measure of pollution-dependent cognitive functioning, at an individual level.

Conclusions

Taken together, these data demonstrate how routine, inexpensive medical testing and local authority initiatives could help to identify and protect at-risk individuals. These findings highlight the potential to identify individuals for targeted, cost effective medical and social interventions to improve population cognitive health.

[Psyche in Climate Crisis?An Update on Ecological Psychiatry and Psychotherapy]

The human-caused climate crisis is advancing relentlessly and poses a global threat. But to what extent is our psyche also in crisis due to climate change? This article explores the profound impacts of the climate crisis and environmental destruction on mental health, advocating for a comprehensive, ecologically-oriented approach to psychiatry and psychotherapy.

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.

Air pollution is linked to cognitive decline independent of hypersensitive C-reactive protein: insights from middle-aged and older Chinese

BACKGROUND

Long-term air pollution exposure and inflammation are considered to be associated with cognitive decline. However, whether air pollution exposure related cognitive decline is dependent on inflammation remains uncertain.

MATERIALS AND METHODS

The present study collected data from China Health and Retirement Longitudinal Study (CHARLS) at baseline in 2011, with a follow up period in 2015. Concentration of air pollutants (particles with diameters ≤ 1.0 μm [PM1], ≤ 2.5 μm [PM2.5], ≤ 10 μm [PM10], nitrogen dioxide [NO2] and ozone [O3]) were obtained from China High Air Pollutants (CHAP) dataset. Hypersensitive C-reactive protein (hs-CRP), a systemic inflammation marker, was measured in blood of subjects and cognitive function was assessed by standardized questionnaire.

RESULTS

A total of 6434 participants were included in the study. Lower exposure to PM2.5, PM1, PM10 and NO2 were associated with mitigated cognitive decline. The odds ratios (ORs) for air pollutants changes and cognitive decline and 95% confidence intervals (CIs) were as follows: PM2.5-0.934(0.925, 0.943), PM1- 0.945 (0.935,0.955), PM10-0.977(0.972,0.982) and NO2-0.962(0.950,0.975), respectively. Hs-CRP showed no significant correlation with cognitive decline or change in levels of air pollution. The interaction regression analyses, both unadjusted and adjusted, did not uncover any significant correlation between hs-CRP and air pollution with respect to cognitive decline. Bootstrap test exhibited no significant mediating effect of hs-CRP on the relationship between any air pollutants and cognitive decline, the indirect effects of hs-CRP in conjunction with exposure to different air pollutants were all found to be non-significant, with the following bootstrap CIs and p-values: PM2.5-1.000([1.000,1.000], P = 0.480),PM1-1.000([1.000,1.000], P = 0.230),PM10-1.000([1.000,1.000], P = 0.650), O3-1.000([1.000,1.000], P = 0.470), ΔNO2-1.000([1.000,1.000], P = 0.830) .

CONCLUSION

Ambient air pollution exposure was linked to cognitive decline independent of hs-CRP level.

The role of the components of PM 2.5 in the incidence of Alzheimer's disease and related disorders

Background

The associations of PM 2.5 mass and various adverse health outcomes have been widely investigated. However, fewer studies focused on the potential health impacts of PM 2.5 components, especially for dementia and Alzheimer's diseases (AD).

Methods

We constructed a nationwide population-based open cohort study among Medicare beneficiaries aged 65 or older during 2000-2018. This dataset was linked with the predicted levels of 15 PM 2.5 components, including 5 major mass contributors (EC, OC, NH 4 + , NO 3 - , SO 4 2- ) and 10 trace elements (Br, Ca, Cu, Fe, K, Ni, Pb, Si, V, Zn) across contiguous US territory. Data were aggregated by ZIP code, calendar year and individual level demographics. Two mixture analysis methods, weighted quantile sum regression (WQS) and quantile g-computation (qgcomp), were used with quasi-Poisson models to analyze the health effects of the total mixture of PM 2.5 components on dementia and AD, as well as the relative contribution of individual components.

Results

Exposure to PM 2.5 components over the previous 5 years was significantly associated with increased risks of both dementia and AD, with stronger associations observed for AD. SO 4 2- , OC, Cu were identified with large contributions to the combined positive association of the mixture from both WQS and qgcomp models.

Conclusion

We found positive associations between the 15 PM 2.5 components and the incidence of dementia and AD. Our findings suggest that reducing PM 2.5 emissions from traffic and fossil fuel combustion could help mitigate the growing burden of dementia and Alzheimer's disease.

The enigma of mitochondrial epigenetic alterations in air pollution-induced neurodegenerative diseases

The incidence of neurodegenerative diseases is a growing concern worldwide, affecting individuals from diverse backgrounds. Although these pathologies are primarily associated with aging and genetic susceptibility, their severity varies among the affected population. Numerous studies have indicated air pollution as a significant contributor to the increasing prevalence of neurodegeneration. Cohort studies have provided compelling evidence of the association between prolonged exposure to different air toxicants and cognitive decline, behavioural deficits, memory impairment, and overall neuronal health deterioration. Furthermore, molecular research has revealed that air pollutants can disrupt the body's protective mechanisms, participate in neuroinflammatory pathways, and cause neuronal epigenetic modifications. The mitochondrial epigenome is particularly interesting to the scientific community due to its potential to significantly impact our understanding of neurodegenerative diseases' pathogenesis and their release in the peripheral circulation. While protein hallmarks have been extensively studied, the possibility of using circulating epigenetic signatures, such as methylated DNA fragments, miRNAs, and genome-associated factors, as diagnostic tools and therapeutic targets requires further groundwork. The utilization of circulating epigenetic signatures holds promise for developing novel prognostic strategies, creating paramount point-of-care devices for disease diagnosis, identifying therapeutic targets, and developing clinical data-based disease models utilizing multi-omics technologies and artificial intelligence, ultimately mitigating the threat and prevalence of neurodegeneration.

Mechanisms of ozone-induced neurotoxicity in the development and progression of dementia: a brief review

Dementia encompasses a spectrum of neurodegenerative disorders significantly impacting global health, with environmental factors increasingly recognized as crucial in their etiology. Among these, ozone, has been identified as a potential exacerbator of neurodegenerative processes, particularly in Alzheimer's disease (AD). Ozone exposure induces the production of reactive oxygen species (ROS), which penetrate the BBB, leading to oxidative damage in neuronal cells. This oxidative stress is closely linked with mitochondrial dysfunction and lipid peroxidation, processes that are foundational to the pathology observed in dementia, such as neuronal death and protein aggregation. Furthermore, ozone triggers chronic neuroinflammation, exacerbating these neurodegenerative processes and perpetuating a cycle of CNS damage. Recent studies highlight the role of peripheral biomarkers like High Mobility Group Box 1 (HMGB1) and Triggering Receptor Expressed on Myeloid cells 2 (TREM2) in mediating ozone's effects. Disruption of these and other identified proteins by ozone exposure impairs microglial function and response to amyloid plaques, suggesting a novel pathway through which ozone may influence AD pathology via immune dysregulation. This review discusses the concept of a bidirectional lung-brain axis, illustrating that systemic responses to air pollutants like ozone may reflect and contribute to neurodegenerative processes in the CNS. By delineating these mechanisms, we emphasize the critical need for integrating environmental health management into strategies for the prevention and treatment of dementia.

Use of machine learning algorithms to determine the relationship between air pollution and cognitive impairment in Taiwan

Air pollution has become a major global threat to human health. Urbanization and industrialization over the past few decades have increased the air pollution. Plausible connections have been made between air pollutants and dementia. This study used machine learning algorithms (k-nearest neighbors, random forest, gradient-boosted decision trees, eXtreme gradient boosting, and CatBoost) to investigate the association between cognitive impairment and air pollution. Data from the Taiwan Biobank and 75 air-pollution-monitoring stations in Taiwan were analyzed to determine individual levels of exposure to air pollutants. The pollutants examined were particulate matter with a diameter of ≤ 2.5 μm (PM2.5), nitrogen dioxide, nitric oxide, carbon monoxide, and ozone. The results revealed that the most strongly correlated with cognitive impairment were ozone, PM2.5, and carbon monoxide levels with adjustment of educational level, age, and household income. The model based on these factors achieved accuracy as high as 0.97 for detecting cognitive impairment, indicating a positive association between air pollutions and cognitive impairment.

Association of ambient air pollution with cognitive functioning and markers of structural brain damage: The Maastricht study

INTRODUCTION

Given the absence of curative interventions and the rising global incidence of dementia, research is increasingly focusing on lifestyle factors for prevention. However, identifying shared environmental risk for dementia, next to individual factors, is crucial for optimal risk reduction strategies. Therefore, in the present study we investigated the association between air pollution, cognitive functioning, and markers of structural brain damage.

METHODS

We used cross-sectional data from 4,002 participants of The Maastricht Study on volumetric markers of brain integrity (white and grey matter volume, cerebrospinal fluid volume, white matter hyperintensities volume, presence of cerebral small vessel disease) and cognitive functioning (memory, executive functioning and attention, processing speed, overall cognition). Individuals were matched by postal code of residence to nationwide data on air pollution exposure (particulate matter < 2.5 μm (PM2.5), particulate matter <10 μm (PM10), nitrogen dioxide (NO2), soot). Potentia linear and non-linear associations were investigated with linear, logistic, and restricted cubic splines regression. All analyses were adjusted for demographic characteristics and a compound score of modifiable dementia risk and protective factors.

RESULTS

Exposure to air pollutants was not related to cognitive functioning and most brain markers. We found curvilinear relationships between high PM2.5 exposures and grey matter and cerebrospinal fluid volume. Participants in the low and high range of exposure had lower grey matter volume. Higher cerebrospinal fluid volumes were only associated with high range of exposure, independent of demographic and individual modifiable dementia risk factors. After additional post hoc analyses, controlling for urbanicity, the associations for grey matter volume became non-significant. In men only, higher exposure to all air pollutants was associated with lower white matter volumes. No significant associations with white matter hyperintensities volume or cerebral small vessel disease were observed.

DISCUSSION

Our findings suggest that higher PM2.5 exposure is associated with more brain atrophy.

Racial and ethnic minority representation in dementia risk factor research: a scoping review of cohort studies

BACKGROUND

Despite a potentially greater burden of dementia, racial and ethnic minority populations around the world may be more likely to be excluded from research examining risk factors for incident dementia. We aimed to systematically investigate and quantify racial and ethnic minority representation in dementia risk factor research.

METHODS

We performed a two-stage systematic search of databases-MEDLINE (Ovid SP), Embase (Ovid SP) and Scopus-from inception to March 2021 to identify population-based cohort studies looking at risk factors for dementia incidence. We included cohort studies which were population-based and incorporated a clinical dementia diagnosis.

RESULTS

Out of the 97 identified cohort studies, fewer than half (40 studies; 41%) reported the race or ethnicity of participants and just under one-third (29 studies; 30%) reported the inclusion of racial and ethnic minority groups. We found that inadequate reporting frequently prevented assessment of selection bias and only six studies that included racial and ethnic minority participants were at low risk for measurement bias in dementia diagnosis. In cohort studies including a multiethnic cohort, only 182 out of 337 publications incorporated race or ethnicity in data analysis-predominantly (90%) through adjustment for race or ethnicity as a confounder. Only 14 publications (4.2% of all publications reviewed) provided evidence about drivers of any observed inequalities.

CONCLUSIONS

Racial and ethnic minority representation in dementia risk factor research is inadequate. Comparisons of dementia risk between different racial and ethnic groups are likely hampered by significant selection and measurement bias. Moreover, the focus on 'adjusting out' the effect of race and ethnicity as a confounder prevents understanding of underlying drivers of observed inequalities. There is a pressing need to fundamentally change the way race, ethnicity and the inclusion of racial and ethnic minorities are considered in research if health inequalities are to be adequately addressed.

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.

Associations between Aircraft Noise, Sleep, and Sleep-Wake Cycle: Actimetric Data from the UK Biobank Cohort near Four Major Airports

BACKGROUND

Nighttime aircraft noise may affect people's sleep, yet large-scale evidence using objective and subjective measures remains limited.

OBJECTIVE

Our aim was to investigate associations between nighttime aircraft noise exposure and objectively measured sleep disturbance using a large UK cohort.

METHODS

We used data from 105,770 UK Biobank cohort participants exposed and unexposed to aircraft noise who lived in 44 local authority districts near 4 international airports in England. We used a generalized linear regression model to examine cross-sectional associations between aircraft noise L night (23:00 hours-07:00 hours) and 7-d actimetric measures collected 2013-2015 (n = 22,102 ). We also used Logit and generalized estimating equations models to examine associations between L night and self-reported sleep measures at enrollment (2006-2010) and follow-up (2012-2013). This approach allowed us to compare and contrast the results and support potential future meta-analyses on noise-related sleep disturbance.

RESULTS

Cross-sectional analyses of actimetric data suggested sleep disturbance associated with L night , showing higher level of movements during the least active continuous 8-h time period [β : 0.12 milligravitational units; 95% confidence interval (CI): 0.013, 0.23]. We also saw disrupted sleep-wake cycles as indicated by index scores of lower relative amplitude (β : - 0.006 ; 95% CI: - 0.007 , - 0.005 ), poorer interdaily stability (β : - 0.010 ; 95% CI: - 0.014 , - 0.006 ), and greater intradaily variability (β : 0.021; 95% CI: 0.019, 0.023), comparing L night ≥ 55 dB with < 45 dB. Repeated cross-sectional analyses found a 52% higher odds of more frequent daytime dozing [odds ratio (OR) = 1.52 ; 95% CI: 1.32, 1.75] for L night ≥ 55 dB in comparison with < 45 dB, whereas the likelihood for more frequent sleeplessness was more uncertain (OR = 1.13 ; 95% CI: 0.92, 1.39). Higher effect sizes were seen in preidentified vulnerable groups, including individuals > 65 y of age and those with diabetes or dementia.

CONCLUSION

Individuals exposed to higher levels of aircraft noise experienced objectively higher levels of sleep disturbance and changes in sleep-wake cycle. https://doi.org/10.1289/EHP14156.

Genetic evidence supports a causal relationship between air pollution and brain imaging-derived phenotypes

BACKGROUND

Observational studies have reported associations between air pollutants and brain imaging-derived phenotypes (IDPs); however, whether this relationship is causal remains uncertain.

METHODS

We conducted bidirectional two-sample Mendelian randomization (MR) analyses to explore the causal relationships between 5 types of air pollutants (N=423,796 to 456,380 individuals) and 587 reliable IDPs (N=33,224 individuals). Two-step MR was also conducted to assess whether the identified effects are mediated through the modulation of circulating cytokines (N=8293).

RESULTS

We found genetic evidence supporting the association of nitrogen oxides (NOx) with mean intra-cellular volume fraction (ICVF) in the left uncinate fasciculus (IVW β=-0.42, 95 % CI -0.62 to -0.23, P=1.51×10-5) and mean fractional anisotropy (FA) in the left uncinate fasciculus (IVW β=-0.42, 95 % CI -0.62 to -0.21, P=4.89×10-5). In further two-step MR analyses, we did not find evidence that genetic predictions of any circulating cytokines mediated the association between NOx and IDPs.

CONCLUSION

This study provides evidence for the association between air pollutants and brain IDPs, emphasizing the importance of controlling air pollution to improve brain health.

Charting Alzheimer's Disease and Dementia: Epidemiological Insights, Risk Factors and Prevention Pathways

Alzheimer's disease (AD), the most common cause of dementia, is a complex and multifactorial condition without cure at present. The latest treatments, based on anti-amyloid monoclonal antibodies, have only a modest effect in reducing the progression of cognitive decline in AD, whereas the possibility of preventing AD has become a crucial area of research. In fact, recent studies have observed a decrease in dementia incidence in developed regions such as the US and Europe. However, these trends have not been mirrored in non-Western countries (Japan or China), and the contributing factors of this reduction remain unclear. The Lancet Commission has delineated a constrained classification of 12 risk factors across different life stages. Nevertheless, the scientific literature has pointed to over 200 factors-including sociodemographic, medical, psychological, and sociocultural conditions-related to the development of dementia/AD. This narrative review aims to synthesize the risk/protective factors of dementia/AD. Essentially, we found that risk/protective factors vary between individuals and populations, complicating the creation of a unified prevention strategy. Moreover, dementia/AD explanatory mechanisms involve a diverse array of genetic and environmental factors that interact from the early stages of life. In the future, studies across different population-based cohorts are essential to validate risk/protective factors of dementia. This evidence would help develop public health policies to decrease the incidence of dementia.

Exposure to source-specific air pollution in residential areas and its association with dementia incidence: a cohort study in Northern Sweden

The aim of this study was to investigate the relationship between source-specific ambient particulate air pollution concentrations and the incidence of dementia. The study encompassed 70,057 participants from the Västerbotten intervention program cohort in Northern Sweden with a median age of 40 years at baseline. High-resolution dispersion models were employed to estimate source-specific particulate matter (PM) concentrations, such as PM10 and PM2.5 from traffic, exhaust, and biomass (mainly wood) burning, at the residential addresses of each participant. Cox regression models, adjusted for potential confounding factors, were used for the assessment. Over 884,847 person-years of follow-up, 409 incident dementia cases, identified through national registers, were observed. The study population's average exposure to annual mean total PM10 and PM2.5 lag 1-5 years was 9.50 µg/m3 and 5.61 µg/m3, respectively. Increased risks were identified for PM10-Traffic (35% [95% CI 0-82%]) and PM2.5-Exhaust (33% [95% CI - 2 to 79%]) in the second exposure tertile for lag 1-5 years, although no such risks were observed in the third tertile. Interestingly, a negative association was observed between PM2.5-Wood burning and the risk of dementia. In summary, this register-based study did not conclusively establish a strong association between air pollution exposure and the incidence of dementia. While some evidence indicated elevated risks for PM10-Traffic and PM2.5-Exhaust, and conversely, a negative association for PM2.5-Wood burning, no clear exposure-response relationships were evident.

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

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

Particulate matter constituents trigger the formation of extracellular amyloid β and Tau -containing plaques and neurite shortening in vitro

Air pollution is an environmental factor associated with an increased risk of neurodegenerative diseases, such as Alzheimer's and Parkinson's, characterized by decreased cognitive abilities and memory. The limited models of sporadic Alzheimer's disease fail to replicate all pathological hallmarks of the disease, making it challenging to uncover potential environmental causes. Environmentally driven models of Alzheimer's disease are thus timely and necessary. We used live-cell confocal fluorescent imaging combined with high-resolution stimulated emission depletion (STED) microscopy to follow the response of retinoic acid-differentiated human neuroblastoma SH-SY5Y cells to nanomaterial exposure. Here, we report that exposure of the cells to some particulate matter constituents reproduces a neurodegenerative phenotype, including extracellular amyloid beta-containing plaques and decreased neurite length. Consistent with the existing in vivo research, we observed detrimental effects, specifically a substantial reduction in neurite length and formation of amyloid beta plaques, after exposure to iron oxide and diesel exhaust particles. Conversely, after exposure to engineered cerium oxide nanoparticles, the lengths of neurites were maintained, and almost no extracellular amyloid beta plaques were formed. Although the exact mechanism behind this effect remains to be explained, the retinoic acid differentiated SH-SY5Y cell in vitro model could serve as an alternative, environmentally driven model of neurodegenerative diseases, including Alzheimer's disease.

Association of Gaseous Ambient Air Pollution and Dementia-Related Neuroimaging Markers in the ARIC Cohort, Comparing Exposure Estimation Methods and Confounding by Study Site

BACKGROUND

Evidence linking gaseous air pollution to late-life brain health is mixed.

OBJECTIVE

We explored associations between exposure to gaseous pollutants and brain magnetic resonance imaging (MRI) markers among Atherosclerosis Risk in Communities (ARIC) Study participants, with attention to the influence of exposure estimation method and confounding by site.

METHODS

We considered data from 1,665 eligible ARIC participants recruited from four US sites in the period 1987-1989 with valid brain MRI data from Visit 5 (2011-2013). We estimated 10-y (2001-2010) mean carbon monoxide (CO), nitrogen dioxide (NO 2 ), nitrogen oxides (NO x ), and 8- and 24-h ozone (O 3 ) concentrations at participant addresses, using multiple exposure estimation methods. We estimated site-specific associations between pollutant exposures and brain MRI outcomes (total and regional volumes; presence of microhemorrhages, infarcts, lacunes, and severe white matter hyperintensities), using adjusted linear and logistic regression models. We compared meta-analytically combined site-specific associations to analyses that did not account for site.

RESULTS

Within-site exposure distributions varied across exposure estimation methods. Meta-analytic associations were generally not statistically significant regardless of exposure, outcome, or exposure estimation method; point estimates often suggested associations between higher NO 2   and   NO x and smaller temporal lobe, deep gray, hippocampal, frontal lobe, and Alzheimer disease signature region of interest volumes and between higher CO and smaller temporal and frontal lobe volumes. Analyses that did not account for study site more often yielded significant associations and sometimes different direction of associations.

DISCUSSION

Patterns of local variation in estimated air pollution concentrations differ by estimation method. Although we did not find strong evidence supporting impact of gaseous pollutants on brain changes detectable by MRI, point estimates suggested associations between higher exposure to CO, NO x , and NO 2 and smaller regional brain volumes. Analyses of air pollution and dementia-related outcomes that do not adjust for location likely underestimate uncertainty and may be susceptible to confounding bias. https://doi.org/10.1289/EHP13906.

The longitudinal associations between ambient air pollution exposure and dementia in the UK: results from the cognitive function and ageing study II and Wales

BACKGROUND

Air pollution has been recognised as a potential risk factor for dementia. Yet recent epidemiological research shows mixed evidence. The aim of this study is to investigate the longitudinal associations between ambient air pollution exposure and dementia in older people across five urban and rural areas in the UK.

METHODS

This study was based on two population-based cohort studies of 11329 people aged ≥ 65 in the Cognitive Function and Ageing Study II (2008-2011) and Wales (2011-2013). An algorithmic diagnosis method was used to identify dementia cases. Annual concentrations of four air pollutants (NO2, O3, PM10, PM2.5) were modelled for the year 2012 and linked via the participants' postcodes. Multistate modelling was used to examine the effects of exposure to air pollutants on incident dementia incorporating death and adjusting for sociodemographic factors and area deprivation. A random-effect meta-analysis was carried out to summarise results from the current and nine existing cohort studies.

RESULTS

Higher exposure levels of NO2 (HR: 1.04; 95% CI: 0.94, 1.14), O3 (HR: 0.90; 95% CI: 0.70, 1.15), PM10 (HR: 1.17; 95% CI: 0.86, 1.58), PM2.5 (HR: 1.41; 95% CI: 0.71, 2.79) were not strongly associated with dementia in the two UK-based cohorts. Inconsistent directions and strengths of the associations were observed across the two cohorts, five areas, and nine existing studies.

CONCLUSIONS

In contrast to the literature, this study did not find clear associations between air pollution and dementia. Future research needs to investigate how methodological and contextual factors can affect evidence in this field and clarity the influence of air pollution exposure on cognitive health over the lifecourse.

Association of PM2.5 Exposure and Alzheimer Disease Pathology in Brain Bank Donors-Effect Modification by APOE Genotype

BACKGROUND AND OBJECTIVES

Fine particulate matter (PM2.5) exposure has been found to be associated with Alzheimer disease (AD) and is hypothesized to cause inflammation and oxidative stress in the brain, contributing to neuropathology. The APOE gene, a major genetic risk factor of AD, has been hypothesized to modify the association between PM2.5 and AD. However, little prior research exists to support these hypotheses. This study investigates the association between traffic-related PM2.5 and AD hallmark pathology, including effect modification by APOE genotype, in an autopsy cohort.

METHODS

A cross-sectional study was conducted using brain tissue donors enrolled in the Emory Goizueta AD Research Center who died before 2020 (n = 224). Donors were assessed for AD pathology including the Braak stage, Consortium to Establish a Registry for AD (CERAD) score, and combined AD neuropathologic change (ABC) score. Traffic-related PM2.5 concentrations were modeled for the metro-Atlanta area during 2002-2019 with a spatial resolution of 200-250 m. One-year, 3-year, and 5-year average PM2.5 concentrations before death were matched to participants' home address. We assessed the association between traffic-related PM2.5 and AD hallmark pathology and effect modification by APOE genotype, using adjusted ordinal logistic regression models.

RESULTS

Among the 224 participants, the mean age of death was 76 years, and 57% had at least 1 APOE ε4 copy. Traffic-related PM2.5 was significantly associated with the CERAD score for the 1-year exposure window (odds ratio [OR] 1.92; 95% CI 1.12-3.30) and the 3-year exposure window (OR 1.87; 95% CI 1.01-3.17). PM2.5 was also associated with higher Braak stage and ABC score albeit nonsignificantly. The strongest associations between PM2.5 and neuropathology markers were among those without APOE ε4 alleles (e.g., for the CERAD score and 1-year exposure window, OR 2.31; 95% CI 1.36-3.94), though interaction between PM2.5 and APOE genotype was not statistically significant.

DISCUSSION

Our study found traffic-related PM2.5 exposure was associated with the CERAD score in an autopsy cohort, contributing to epidemiologic evidence that PM2.5 affects β-amyloid deposition in the brain. This association was particularly strong among donors without APOE ε4 alleles. Future studies should further investigate the biological mechanisms behind this association.

Machine learning and XAI approaches highlight the strong connection between O 3 and N O 2 pollutants and Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia with millions of affected patients worldwide. Currently, there is still no cure and AD is often diagnosed long time after onset because there is no clear diagnosis. Thus, it is essential to study the physiology and pathogenesis of AD, investigating the risk factors that could be strongly connected to the disease onset. Despite AD, like other complex diseases, is the result of the combination of several factors, there is emerging agreement that environmental pollution should play a pivotal role in the causes of disease. In this work, we implemented an Artificial Intelligence model to predict AD mortality, expressed as Standardized Mortality Ratio, at Italian provincial level over 5 years. We employed a set of publicly available variables concerning pollution, health, society and economy to feed a Random Forest algorithm. Using methods based on eXplainable Artificial Intelligence (XAI) we found that air pollution (mainly O 3 and N O 2 ) contribute the most to AD mortality prediction. These results could help to shed light on the etiology of Alzheimer's disease and to confirm the urgent need to further investigate the relationship between the environment and the disease.

Joint Exposure to Multiple Air Pollutants, Genetic Susceptibility, and Incident Dementia: A Prospective Analysis in the UK Biobank Cohort

Objectives: This study aimed to evaluate the joint effects of multiple air pollutants including PM2.5, PM10, NO2, and NOx with dementia and examined the modifying effects of genetic susceptibility. Methods: This study included 220,963 UK Biobank participants without dementia at baseline. Weighted air pollution score reflecting the joint exposure to multiple air pollutants were constructed by cross-validation analyses, and inverse-variance weighted meta-analyses were performed to create a pooled effect. The modifying effect of genetic susceptibility on air pollution score was assessed by genetic risk score and APOE ε4 genotype. Results: The HR (95% CI) of dementia for per interquartile range increase of air pollution score was 1.13 (1.07∼1.18). Compared with the lowest quartile (Q1) of air pollution score, the HR (95% CI) of Q4 was 1.26 (1.13∼1.40) (P trend = 2.17 × 10-5). Participants with high air pollution score and high genetic susceptibility had higher risk of dementia compared to those with low air pollution score and low genetic susceptibility. Conclusion: Our study provides evidence that joint exposure to multiple air pollutants substantially increases the risk of dementia, especially among individuals with high genetic susceptibility.

Health position paper and redox perspectives - Disease burden by transportation noise

Transportation noise is a ubiquitous urban exposure. In 2018, the World Health Organization concluded that chronic exposure to road traffic noise is a risk factor for ischemic heart disease. In contrast, they concluded that the quality of evidence for a link to other diseases was very low to moderate. Since then, several studies on the impact of noise on various diseases have been published. Also, studies investigating the mechanistic pathways underlying noise-induced health effects are emerging. We review the current evidence regarding effects of noise on health and the related disease-mechanisms. Several high-quality cohort studies consistently found road traffic noise to be associated with a higher risk of ischemic heart disease, heart failure, diabetes, and all-cause mortality. Furthermore, recent studies have indicated that road traffic and railway noise may increase the risk of diseases not commonly investigated in an environmental noise context, including breast cancer, dementia, and tinnitus. The harmful effects of noise are related to activation of a physiological stress response and nighttime sleep disturbance. Oxidative stress and inflammation downstream of stress hormone signaling and dysregulated circadian rhythms are identified as major disease-relevant pathomechanistic drivers. We discuss the role of reactive oxygen species and present results from antioxidant interventions. Lastly, we provide an overview of oxidative stress markers and adverse redox processes reported for noise-exposed animals and humans. This position paper summarizes all available epidemiological, clinical, and preclinical evidence of transportation noise as an important environmental risk factor for public health and discusses its implications on the population level.

Potential Effects of Long-Term Exposure to Air Pollution on Dementia: A Longitudinal Analysis in American Indians Aged 55 Years and Older

(1) Background: American Indians are disproportionately affected by air pollution, an important risk factor for dementia. However, few studies have investigated the effects of air pollution on the risk of dementia among American Indians. (2) Methods: This retrospective cohort study included a total of 26,871 American Indians who were 55+ years old in 2007, with an average follow-up of 3.67 years. County-level average air pollution data were downloaded from land-use regression models. All-cause dementia was identified using ICD-9 diagnostic codes from the Indian Health Service's (IHS) National Data Warehouse and related administrative databases. Cox models were employed to examine the association of air pollution with dementia incidence, adjusting for co-exposures and potential confounders. (3) Results: The average PM2.5 levels in the IHS counties were lower than those in all US counties, while the mean O3 levels in the IHS counties were higher than the US counties. Multivariable Cox regressions revealed a positive association between dementia and county-level O3 with a hazard ratio of 1.24 (95% CI: 1.02-1.50) per 1 ppb standardized O3. PM2.5 and NO2 were not associated with dementia risk after adjusting for all covariates. (4) Conclusions: O3 is associated with a higher risk of dementia among American Indians.

Can Incorrect Analysis of Time-Dependent Exposure Explain Associations between PM2.5 Exposure and Risk of Dementia?

Background

Epidemiological studies have reported positive associations between long-term exposure to particulate matter of 2.5 microns or less in diameter (PM2.5) and risk of Alzheimer's disease and other clinical dementia. Many of these studies have analyzed data using Cox Proportional Hazards (PH) regression, which estimates a hazard ratio (HR) for the treatment (in this case, exposure) effect on the time-to-event outcome while adjusting for influential covariates. PM2.5 levels vary over time. As air quality standards for PM2.5 have become more stringent over time, average outdoor PM2.5 levels have decreased substantially.

Objective

Investigate whether a Cox PH analysis that does not properly account for exposure that varies over time could produce a biased HR of similar magnitude to the HRs reported in recent epidemiological studies of PM2.5 and dementia risk.

Methods

Simulation analysis.

Results

We found that the biased HR can affect statistical analyses that consider exposure levels at event times only, especially if PM2.5 levels decreased consistently over time. Furthermore, the direction of such bias is away from the null and of a magnitude that is consistent with the reported estimates of dementia risk in several epidemiological studies of PM2.5 exposure (HR≈1.2 to 2.0).

Conclusions

This bias can be avoided by correctly assigning exposure to study subjects throughout the entire follow-up period. We recommend that investigators provide a detailed description of how time-dependent exposure variables were accounted for in their Cox PH analyses when they report their results.

Traffic-related air pollution and dementia incidence in the Adult Changes in Thought Study

BACKGROUND

While epidemiologic evidence links higher levels of exposure to fine particulate matter (PM2.5) to decreased cognitive function, fewer studies have investigated links with traffic-related air pollution (TRAP), and none have examined ultrafine particles (UFP, ≤100 nm) and late-life dementia incidence.

OBJECTIVE

To evaluate associations between TRAP exposures (UFP, black carbon [BC], and nitrogen dioxide [NO2]) and late-life dementia incidence.

METHODS

We ascertained dementia incidence in the Seattle-based Adult Changes in Thought (ACT) prospective cohort study (beginning in 1994) and assessed ten-year average TRAP exposures for each participant based on prediction models derived from an extensive mobile monitoring campaign. We applied Cox proportional hazards models to investigate TRAP exposure and dementia incidence using age as the time axis and further adjusting for sex, self-reported race, calendar year, education, socioeconomic status, PM2.5, and APOE genotype. We ran sensitivity analyses where we did not adjust for PM2.5 and other sensitivity and secondary analyses where we adjusted for multiple pollutants, applied alternative exposure models (including total and size-specific UFP), modified the adjustment covariates, used calendar year as the time axis, assessed different exposure periods, dementia subtypes, and others.

RESULTS

We identified 1,041 incident all-cause dementia cases in 4,283 participants over 37,102 person-years of follow-up. We did not find evidence of a greater hazard of late-life dementia incidence with elevated levels of long-term TRAP exposures. The estimated hazard ratio of all-cause dementia was 0.98 (95 % CI: 0.92-1.05) for every 2000 pt/cm3 increment in UFP, 0.95 (0.89-1.01) for every 100 ng/m3 increment in BC, and 0.96 (0.91-1.02) for every 2 ppb increment in NO2. These findings were consistent across sensitivity and secondary analyses.

DISCUSSION

We did not find evidence of a greater hazard of late-life dementia risk with elevated long-term TRAP exposures in this population-based prospective cohort study.

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.

Alzheimer's Disease and Suicide: An Integrative Literature Review

INTRODUCTION

Suicide has been described in patients with Alzheimer's disease. Some promising medications for treating Alzheimer's disease have had their studies suspended because they increase the risk of suicide. Understanding the correlations between suicide and Alzheimer's disease is essential in an aging world.

METHODS

A search was carried out on electronic websites (PubMed and Scielo) using the MeSH Terms "suicide" and "Alzheimer" (1986-2023). Of a total of 115 articles, 26 were included in this review.

RESULTS

Depression and the allele ε4 of Apolipoprotein (APOE4) were demonstrated to be the main risk factors for suicide in patients with Alzheimer's disease.

CONCLUSION

Adequately delineating which elderly people are vulnerable to suicide is important so that new treatments for Alzheimer's disease can be successful. This review showed a need for new studies to investigate the interface between Alzheimer's disease and suicide.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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

The Association Between Exposure to Air Pollution and Dementia Incidence: The Modifying Effect of Smoking

BACKGROUND

The influence of overall air pollution on dementia risk and the potential effect modification by other risk factors remain to be clarified.

METHODS

We included 459 844 UK residents who were free of dementia and had data on the exposure to particulate matter (PM)2.5, PM2.5-10, PM10, NO2, and NOx during baseline recruitment. The combined exposure to various PMs and NOx was estimated by using an air pollution score. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident dementia were estimated by multivariable Cox models.

RESULTS

During a median 11.7 years follow-up, 5 905 incident cases of all-cause dementia were identified. With the exception of PM2.5-10, all other air pollutants were separately associated with a higher risk of all-cause dementia (all p-trend < .001) with generally similar associations for dementia subtypes. An increasing air pollution score was associated with higher risks of all-cause as well as individual dementia outcomes, with adjusted HRs (95% CI) of 1.27 (1.18, 1.37) for all-cause dementia, 1.27 (1.14, 1.43) for Alzheimer's disease, and 1.35 (1.16, 1.57) for vascular dementia when comparing the highest with the lowest quartile of the score (all p-trend < .001). These associations of air pollution score with dementia and its subtypes were observed among never and former smokers but not among current smokers (all p-interaction 
< .030).

CONCLUSION

Air pollution was associated with a higher risk of dementia among nonsmokers but not current smokers. Additional studies are required to confirm our findings and to explore the potential mechanisms underlying the possible effect modification by smoking status.

Alzheimer`s disease mortality in the United States: Cross-sectional analysis of county-level socio-environmental factors

BACKGROUND

Geographical disparities in mortality among Alzheimer`s disease (AD) patients have been reported and complex sociodemographic and environmental determinants of health (SEDH) may be contributing to this variation. Therefore, we aimed to explore high-risk SEDH factors possibly associated with all-cause mortality in AD across US counties using machine learning (ML) methods.

METHODS

We performed a cross-sectional analysis of individuals ≥65 years with any underlying cause of death but with AD in the multiple causes of death certificate (ICD-10,G30) between 2016 and 2020. Outcomes were defined as age-adjusted all-cause mortality rates (per 100,000 people). We analyzed 50 county-level SEDH and Classification and Regression Trees (CART) was used to identify specific county-level clusters. Random Forest, another ML technique, evaluated variable importance. CART`s performance was validated using a "hold-out" set of counties.

RESULTS

Overall, 714,568 individuals with AD died due to any cause across 2,409 counties during 2016-2020. CART identified 9 county clusters associated with an 80.1% relative increase of mortality across the spectrum. Furthermore, 7 SEDH variables were identified by CART to drive the categorization of clusters, including High School Completion (%), annual Particulate Matter 2.5 Level in Air, live births with Low Birthweight (%), Population under 18 years (%), annual Median Household Income in US dollars ($), population with Food Insecurity (%), and houses with Severe Housing Cost Burden (%).

CONCLUSION

ML can aid in the assimilation of intricate SEDH exposures associated with mortality among older population with AD, providing opportunities for optimized interventions and resource allocation to reduce mortality among this population.

To promote healthy aging, focus on the environment

To build health equity for an aging world marked by dramatic disparities in healthy lifespan between countries, regions and population groups, research at the intersections of biology, toxicology and the social and behavioral sciences points the way: to promote healthy aging, focus on the environment. In this Perspective, we suggest that ideas and tools from the emerging field of geroscience offer opportunities to advance the environmental science of aging. Specifically, the capacity to measure the pace and progress of biological processes of aging within individuals from relatively young ages makes it possible to study how changing environments can change aging trajectories from early in life, in time to prevent or delay aging-related disease and disability and build aging health equity.

Perception of Noise Pollution Among Youths and Adults in Urban Puducherry, South India

Objective The study seeks to assess the perceptions of people on evaluating the sources of noise, noise-induced health issues, and noise regulation awareness among the exposed population present in the study site of urban Puducherry, South India. Methods A cross-sectional survey using a pre-tested semi-structured questionnaire was conducted between July and August 2021 in 32 study sites in urban Puducherry to evaluate how adults and youth perceive noise pollution. The questionnaire gathered details on their sociodemographic characteristics, knowledge of the problems associated with noise pollution, source of noise pollution, effects of noise on health, and awareness of regulations related to noise pollution. Results Half of the study participants perceive that noise pollution is a problem in their localities; the majority feel disturbed by that noise; and the most prevalent reason given for noise pollution is traffic noise. Most of the participants reported that trouble paying attention to work or conversations was the most frequent health impact of noise pollution. Participants who are employed, have formal education, belong to families above the poverty line, and reside near the main road and sub-main road (less than 200 meters) showed a significant association (p-value <0.05) with perceived noise pollution problems. Conclusion Based on the findings, it can be concluded that respondents in urban Puducherry perceive traffic noise as the most common source of noise pollution. The majority of the participants felt that the excessive noise made it difficult for them to focus on their work. Individuals who reside or work close to a major highway and outdoor workers believe noise pollution is a big problem.

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.

Early tactile stimulation influences the development of Alzheimer's disease in gestationally stressed APP NL-G-F adult offspring NL-G-F/NL-G-F mice

Alzheimer's disease (AD) is associated with cerebral plaques and tangles, reduced synapse number, and shrinkage in several brain areas and these morphological effects are associated with the onset of compromised cognitive, motor, and anxiety-like behaviours. The appearance of both anatomical and behavioural symptoms is worsened by stress. The focus of this study was to examine the effect of neonatal tactile stimulation on AD-like behavioural and neurological symptoms on APP NL-G-F/NL-G-F mice, a mouse model of AD, who have been gestationally stressed. Our findings indicate that neonatal tactile stimulation improves cognition, motor skills, and anxiety-like symptoms in both gestationally stressed and non-stressed adult APP mice and that these alterations are associated with reduced Aβ plaque formation. Thus, tactile stimulation appears to be a promising non-invasive preventative strategy for slowing the onset of dementia in aging animals.

Environmental violence: a tool for planetary health research

From climate change to toxic pollution and the interactive effects of multiple pollution streams, human health is under siege. Human-produced environmental risks to health and wellbeing are high and contributing to patterns of global morbidity, mortality, economic inequality, displacement, and insecurity. The implications of human-produced environmental harms to global health are complex just as are their causes. The concept of environmental violence offers a potentially robust frame for engaging this issue. We argue that a more specified and structured framework and definition of environmental violence-focusing on human-produced harms by way of pollution emissions-is both timely and beneficial for engaging the complexities of global public health. To clarify why and how this is the case, we review the literature for publications that use the term environmental violence and we subsequently propose a specific definition focused on human-produced pollution along with a framework for tracking and analysing environmental violence and its constituent components. Finally, we discuss the potential value of our framework for research and policy making regarding human health.

Effect of indoor air quality on the association of long-term exposure to low-level air pollutants with cognition in older adults

BACKGROUND

How indoor air quality affects the temporal associations of long-term exposure to low-level air pollutants with cognition remains unclear.

METHODS

This cohort study (2011-2019) included 517 non-demented older adults at baseline with four repeated cognitive assessments. The time-varying exposure to PM2.5, PM10, NO2, SO2, CO, and O3 was estimated for each participant from 1994 to 2019. Indoor air quality was determined by ventilation status and daily indoor time. Generalized linear mixed models were used to analyze the association of air pollutants, indoor air quality, and cognition adjusting for important covariates.

RESULTS

Over time, per 2.97 μg/m3 (i.e., an interquartile range) increment of PM2.5 was associated with the poor performance of memory (Z score of a cognitive test, βˆ:-0.14), attention (βˆ:-0.13), and executive function (βˆ:-0.20). Similarly, per 2.05 μg/m3 increase in PM2.5-10 was associated with poor global cognition [adjusted odds ratio (aOR): 1.48, βˆ:-0.28], attention (βˆ:-0.07), and verbal fluency (βˆ:-0.09); per 4.94 μg/m3 increase in PM10 was associated with poor global cognition (aOR: 1.78; βˆ:-0.37). In contrast, per 2.74 ppb increase in O3 was associated with better global cognition (βˆ:0.36 to 0.47). These associations became more evident in participants with poor ventilation or short daily indoor time (<12.5 h/day). For global cognition, the exposure to a 10-μg/m3 increment in PM2.5, PM2.5-10, and PM10 corresponded to 1.4, 5.8, and 2.8 years of aging, respectively.

CONCLUSION

This study demonstrated how indoor air quality in areas using clean fuels differentially affected the associations of long-term exposure to low-level air pollutants with cognition. Tightening air quality standards may help prevent dementia.

The impact of Alzheimer's disease risk factors on the pupillary light response

Alzheimer's disease (AD) is the leading cause of dementia, and its prevalence is increasing and is expected to continue to increase over the next few decades. Because of this, there is an urgent requirement to determine a way to diagnose the disease, and to target interventions to delay and ideally stop the onset of symptoms, specifically those impacting cognition and daily livelihood. The pupillary light response (PLR) is controlled by the sympathetic and parasympathetic branches of the autonomic nervous system, and impairments to the pupillary light response (PLR) have been related to AD. However, most of these studies that assess the PLR occur in patients who have already been diagnosed with AD, rather than those who are at a higher risk for the disease but without a diagnosis. Determining whether the PLR is similarly impaired in subjects before an AD diagnosis is made and before cognitive symptoms of the disease begin, is an important step before using the PLR as a diagnostic tool. Specifically, identifying whether the PLR is impaired in specific at-risk groups, considering both genetic and non-genetic risk factors, is imperative. It is possible that the PLR may be impaired in association with some risk factors but not others, potentially indicating different pathways to neurodegeneration that could be distinguished using PLR. In this work, we review the most common genetic and lifestyle-based risk factors for AD and identify established relationships between these risk factors and the PLR. The evidence here shows that many AD risk factors, including traumatic brain injury, ocular and intracranial hypertension, alcohol consumption, depression, and diabetes, are directly related to changes in the PLR. Other risk factors currently lack sufficient literature to make any conclusions relating directly to the PLR but have shown links to impairments in the parasympathetic nervous system; further research should be conducted in these risk factors and their relation to the PLR.

Perspective on Particulate Matter: From Biomass Burning to the Health Crisis in Mainland Southeast Asia

Air pollution, notably particulate matter pollution, has become a serious concern in Southeast Asia in recent decades. The combustion of biomass has been recognized to considerably increase air pollution problems from particulate matter in this region. Consequently, its effect on people in this area is significant. This article presents a synthesis of several datasets obtained from satellites, global emissions, global reanalysis, and the global burden of disease (GBD) to highlight the air quality issue and emphasize the health crisis in mainland Southeast Asia. We found that the death rates of people have increased significantly along with the rise of hotspots in mainland Southeast Asia over the last two decades (2000-2019). In comparison, most countries saw a considerable increase in the predicted fatality rates associated with chronic respiratory illnesses during those two decades. Several reports highlight the continued prevalence of chronic respiratory diseases likely related to poor air quality in Southeast Asia.

Residential greenness, air pollution and incident neurodegenerative disease: A cohort study in China

BACKGROUND

Neurodegenerative disease has a great adverse impact on population's death and disability worldwide. However, the association of air pollution and residential greenness with neurodegenerative disease and their potential mechanisms still remain uncertain.

METHODS

We used data from a population-based prospective cohort in Ningbo, China. Exposure to PM_2.5, PM₁₀ and NO₂ were assessed by land-use regression (LUR) models and residential greenness was estimated by Normalized Difference Vegetation Index (NDVI). Our primary outcomes were all neurodegenerative diseases, Parkinson's disease (PD) and Alzheimer's disease (AD). Cox proportional hazards regression models were used to examine the association of air pollution and residential greenness with risk of incident neurodegenerative disease. Furthermore, we also explored the potential mediation relationship and effect modification between greenness and air pollutants.

RESULTS

During the follow-up period, we identified a total of 617 incident neurodegenerative diseases, 301 PD and 182 AD. In single-exposure models, PM_2.5 was positively associated with all outcomes (e.g. AD hazard ratio (HR): 1.41, 95 % confidence interval (CI): 1.09-1.84, per interquartile range (IQR) increment), whereas residential greenness showed protective effects (e.g. neurodegenerative disease, HR: 0.82, 95%CI: 0.75-0.90, per IQR increment for NDVI in 1000 m buffer). NO₂ was positively associated with risk of neurodegenerative disease and PM₁₀ was associated with neurodegenerative disease and AD. In two-exposure models, after adjustment for PM_2.5, the association for greenness generally attenuated towards null. Moreover, we identified the significant modification effect of greenness on PM2.5 on additive and multiplicative scales.

CONCLUSION

In this prospective study, we found that exposure to higher residential greenness and lower concentrations of particulate matter were associated with lower risk of neurodegenerative disease, PD and AD. Residential greenness could modify the association of PM_2.5 with neurodegenerative disease.

Air pollution is associated with faster cognitive decline in Alzheimer's disease

OBJECTIVE

Although chronic exposure to air pollution is associated with an increased risk of dementia in normal elderlies, the effect of chronic exposure to air pollution on the rates of cognitive decline in Alzheimer's disease (AD) has not been elucidated.

METHODS

In this longitudinal study, a total of 269 patients with mild cognitive impairment or early dementia due to AD with the evidence of brain β-amyloid deposition were followed-up for a mean period of 4 years. Five-year normalized hourly cumulative exposure value of each air pollutant, such as carbon monoxide (CO), nitrogen dioxide (NO2 ), sulfur dioxide (SO2 ), and particulate matter (PM2.5 and PM10 ), was computed based on nationwide air pollution database. The effects of chronic exposure to air pollution on longitudinal cognitive decline rate were evaluated using linear mixed models.

RESULTS

Higher chronic exposure to SO2 was associated with a faster decline in memory score, whereas chronic exposure to CO, NO2 , and PM10 were not associated with the rate of cognitive decline. Higher chronic exposure to PM2.5 was associated with a faster decline in visuospatial score in apolipoprotein E ε4 carriers. These effects remained significant even after adjusting for potential confounders.

INTERPRETATION

Our findings suggest that chronic exposure to SO2 and PM2.5 is associated with faster clinical progression in AD.

Exposure to quasi-ultrafine particulate matter accelerates memory impairment and Alzheimer's disease-like neuropathology in the AppNL-G-F knock-in mouse model

Exposure to traffic-related air pollution consisting of particulate matter (PM) is associated with cognitive decline leading to Alzheimer's disease (AD). In this study, we sought to examine the neurotoxic effects of exposure to ultrafine PM and how it exacerbates neuronal loss and AD-like neuropathology in wildtype (WT) mice and a knock-in mouse model of AD (AppNL-G-F/+-KI) when the exposure occurs at a prepathologic stage or at a later age with the presence of neuropathology. AppNL-G-F/+-KI and WT mice were exposed to concentrated ultrafine PM from local ambient air in Irvine, California, for 12 weeks, starting at 3 or 9 months of age. Particulate matter-exposed animals received concentrated ultrafine PM up to 8 times above the ambient levels, whereas control animals were exposed to purified air. Particulate matter exposure resulted in a marked impairment of memory tasks in prepathologic AppNL-G-F/+-KI mice without measurable changes in amyloid-β pathology, synaptic degeneration, and neuroinflammation. At aged, both WT and AppNL-G-F/+-KI mice exposed to PM showed a significant memory impairment along with neuronal loss. In AppNL-G-F/+-KI mice, we also detected an increased amyloid-β buildup and potentially harmful glial activation including ferritin-positive microglia and C3-positive astrocytes. Such glial activation could promote the cascade of degenerative consequences in the brain. Our results suggest that exposure to PM impairs cognitive function at both ages while exacerbation of AD-related pathology and neuronal loss may depend on the stage of pathology, aging, and/or state of glial activation. Further studies will be required to unveil the neurotoxic role of glial activation activated by PM exposure.

Air Pollution: Role of Extracellular Vesicles-Derived Non-Coding RNAs in Environmental Stress Response

Air pollution has increased over the years, causing a negative impact on society due to the many health-related problems it can contribute to. Although the type and extent of air pollutants are known, the molecular mechanisms underlying the induction of negative effects on the human body remain unclear. Emerging evidence suggests the crucial involvement of different molecular mediators in inflammation and oxidative stress in air pollution-induced disorders. Among these, non-coding RNAs (ncRNAs) carried by extracellular vesicles (EVs) may play an essential role in gene regulation of the cell stress response in pollutant-induced multiorgan disorders. This review highlights EV-transported ncRNAs' roles in physiological and pathological conditions, such as the development of cancer and respiratory, neurodegenerative, and cardiovascular diseases following exposure to various environmental stressors.

Air Pollution: A Silent Key Driver of Dementia

In 2017, the Lancet Commission on Dementia Prevention, Intervention, and Care included air pollution in its list of potential risk factors for dementia; in 2018, the Lancet Commission on Pollution concluded that the evidence for a causal relationship between fine particulate matter (PM) and dementia is encouraging. However, few interventions exist to delay or prevent the onset of dementia. Air quality data are becoming increasingly available, and the science underlying the associated health effects is also evolving rapidly. Recent interest in this area has led to the publication of population-based cohort studies, but these studies have used different approaches to identify cases of dementia. The purpose of this article is to review recent evidence describing the association between exposure to air pollution and dementia with special emphasis on fine particulate matter of 2.5 microns or less. We also summarize here the proposed detailed mechanisms by which air pollutants reach the brain and activate the innate immune response. In addition, the article also provides a short overview of existing limitations in the treatment of dementia.