Early Alzheimer's and Parkinson's disease pathology in urban children: Friend versus Foe responses--it is time to face the evidence

Ambient air pollution and the risk of violence in primary and secondary school settings: a cross-sectional study

BACKGROUND

Individual and social characteristics are attributed to violent behavior in schools, yet environmental hazards may play an understudied role. Ambient air pollution has been linked to neurological dysfunction that inhibits decision-making and may result in violent behavior in adult populations. However, little is known on how air pollution may be associated with violent behaviors in children.

METHODS

A cross-sectional ecologic study was designed to estimate the associations between air pollution (fine particulate matter, carbon monoxide, and nitrogen dioxide) with the occurrence of violent incidents and incidents involving a weapon among a cohort of children in Minnesota schools (2008-2012). Differences by urban and rural status of schools were also explored. Negative binomial regression models were developed to estimate incidence rate ratios (IRR) and incidence rate differences (IRD) to describe associations between air pollution and violent incidents in school settings.

RESULTS

Our results indicate that the highest levels of carbon monoxide, nitrogen dioxide and fine particulate matter concentrations were associated with increased violent disciplinary incidents. Among the total student population, the 4th quartile of carbon monoxide exposure was associated with an IRD of 775.62 (95% CI 543.2, 1008.05) violent incidents per 100,000 students per school year compared to schools in the lowest quartile of exposure. Comparing the 4th to the 1st quartiles of exposure, nitrogen dioxide and fine particulate matter had an IRD of 629.16 (95% CI 384.87, 873.46), and 510.49 (95% CI 274.92, 746.05) violent incidents per 100,000 students per school year respectively. Schools in urban settings shared a larger burden of violent incidents associated with air pollution compared to rural schools.

CONCLUSIONS

Modifying environmental pollutants surrounding school environments, particularly for high exposure communities, may be a novel tool for reducing violence and subsequent injuries in schools.

New light on changes in the number and function of blood platelets stimulated by cocoa and its products

Hyperactivation of blood platelets, one of the causes of heart attack, and other cardiovascular diseases (CVDs), is influenced by various dietary components, including phenolic compounds from vegetables, fruits, teas, wines, cocoa and its products, including chocolate. The present paper sheds new light on the effect of cocoa and its products, especially dark chocolate, on the number and function of blood platelets, and the anti-platelet activity of their constituent phenolic compounds. A review was performed of papers identified in various electronic databases, including PubMed, Science Direct, Scopus, Web of Knowledge, and Google Scholar, with the aim of determining whether their anti-platelet activity may serve as part of a sweet strategy in countering CVDs. Various studies demonstrate that cocoa consumption, especially in the form of dark chocolate, with a high flavanol concentration, has anti-platelet activity and may play a significant role in cardioprotection; they also note that cocoa consumption may be a good strategy in diminishing cardiovascular risk, including hyperactivation of blood platelets.

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.

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.

Perinatal diesel exhaust exposure causes persistent changes in the brains of aged mice: An assessment of behavioral and biochemical endpoints related to neurodegenerative disease

Epidemiological studies support an association between air pollution exposure, specifically particulate matter (PM), and neurodegenerative disease. Diesel exhaust (DE) is a principal component of ambient air pollution and a major contributor of PM. Our study aimed to examine whether early-life perinatal DE exposure is sufficient to affect behavioral and biochemical endpoints related to Alzheimer's disease later in life. To achieve this, mice were perinatally exposed (embryonic day 0-postnatal day 21) to DE (250-300 μg/m3 ) or filtered air (FA), and allowed to reach aged status (>18 months). Mice underwent behavioral assessment at 6 and 20 months of age, with tissue collected at 22 months for biochemical endpoints. At 6 months, minimal changes were noted in home-cage behavior of DE treated animals. At 20 months, an alternation deficit was noted with the T-maze, although no difference was seen in the object location task or any home-cage metrics. DE exposure did not alter the expression of Aβ42, phosphorylated tau S199, or total tau. However, IBA-1 protein, a microglial activation marker, was significantly higher in DE exposed animals. Further, lipid peroxidation levels were significantly higher in the DE exposed animals compared to FA controls. Cytokine levels were largely unchanged with DE exposure, suggesting a lack of inflammation despite persistent lipid peroxidation. Taken together, the findings of this study support that perinatal exposure alone is sufficient to cause lasting changes in the brain, although the effects appear to be less striking than those previously reported in younger animals, suggesting some effects do not persist over time. These findings are encouraging from a public health standpoint and support the aggressive reduction of DE emissions to reduce lifetime exposure and potentially reduce disease outcome.

Mitigating the impact of air pollution on dementia and brain health: Setting the policy agenda

BACKGROUND

Emerging research suggests exposure to high levels of air pollution at critical points in the life-course is detrimental to brain health, including cognitive decline and dementia. Social determinants play a significant role, including socio-economic deprivation, environmental factors and heightened health and social inequalities. Policies have been proposed more generally, but their benefits for brain health have yet to be fully explored.

OBJECTIVE AND METHODS

Over the course of two years, we worked as a consortium of 20+ academics in a participatory and consensus method to develop the first policy agenda for mitigating air pollution's impact on brain health and dementia, including an umbrella review and engaging 11 stakeholder organisations.

RESULTS

We identified three policy domains and 14 priority areas. Research and Funding included: (1) embracing a complexities of place approach that (2) highlights vulnerable populations; (3) details the impact of ambient PM_2.5 on brain health, including current and historical high-resolution exposure models; (4) emphasises the importance of indoor air pollution; (5) catalogues the multiple pathways to disease for brain health and dementia, including those most at risk; (6) embraces a life course perspective; and (7) radically rethinks funding. Education and Awareness included: (8) making this unrecognised public health issue known; (9) developing educational products; (10) attaching air pollution and brain health to existing strategies and campaigns; and (11) providing publicly available monitoring, assessment and screening tools. Policy Evaluation included: (12) conducting complex systems evaluation; (13) engaging in co-production; and (14) evaluating air quality policies for their brain health benefits.

CONCLUSION

Given the pressing issues of brain health, dementia and air pollution, setting a policy agenda is crucial. Policy needs to be matched by scientific evidence and appropriate guidelines, including bespoke strategies to optimise impact and mitigate unintended consequences. The agenda provided here is the first step toward such a plan.

Using wildland fire smoke modeling data in gerontological health research (California, 2007-2018)

Widespread population exposure to wildland fire smoke underscores the urgent need for new techniques to characterize fire-derived pollution for epidemiologic studies and to build climate-resilient communities especially for aging populations. Using atmospheric chemical transport modeling, we examined air quality with and without wildland fire smoke PM2.5. In 12-km gridded output, the 24-hour average concentration of all-source PM2.5 in California (2007-2018) was 5.16 μg/m3 (S.D. 4.66 μg/m3). The average concentration of fire-PM2.5 in California by year was 1.61 μg/m3 (~30% of total PM2.5). The contribution of fire-source PM2.5 ranged from 6.8% to 49%. We define a "smokewave" as two or more consecutive days with modeled levels above 35 μg/m3. Based on model-derived fire-PM2.5, 99.5% of California's population lived in a county that experienced at least one smokewave from 2007 to 2018, yet understanding of the impact of smoke on the health of aging populations is limited. Approximately 2.7 million (56%) of California residents aged 65+ years lived in counties representing the top 3 quartiles of fire-PM2.5 concentrations (2007-2018). For each year (2007-2018), grid cells containing skilled nursing facilities had significantly higher mean concentrations of all-source PM2.5 than cells without those facilities, but they also had generally lower mean concentrations of wildland fire-specific PM2.5. Compared to rural monitors in California, model predictions of wildland fire impacts on daily average PM2.5 carbon (organic and elemental) performed well most years but tended to overestimate wildland fire impacts for high-fire years. The modeling system isolated wildland fire PM2.5 from other sources at monitored and unmonitored locations, which is important for understanding exposures for aging population in health studies.

Neuroprotective approaches to halt Parkinson's disease progression

One of the most significant threats in Parkinson's disease (PD) is neurodegeneration. Neurodegeneration at both nigral as well as non-nigral regions of the brain is considered responsible for disease progression in PD. The key factors that initiate neurodegeneration are oxidative stress, neuroinflammation, mitochondrial complex-1 inhibition, and abnormal α-synuclein (SNCA) protein aggregations. Nigral neurodegeneration results in motor symptoms (tremor, bradykinesia, rigidity, shuffling gait, and postural instability) whereas; non-nigral neurodegeneration is responsible for non-motor symptoms (depression, cognitive dysfunctions, sleep disorders, hallucination, and psychosis). The available therapies for PD aim at increasing dopamine levels. The medications such as Monoamine oxidase B (MAO-B) inhibitors, catechol o-methyltransferase (COMT) inhibitors, Dopamine precursor (Levodopa), dopamine agonists, and dopamine reuptake inhibitors drastically improve the motor symptoms and quality of life only in the early stages of the disease. However, dopa resistant motor symptoms (abnormality in posture, speech impediment, gait, and balance problems), dopa resistant non-motor signs (sleep problems, autonomic dysfunction, mood, and cognitive impairment, pain), and drug-related side effects (motor fluctuations, psychosis, and dyskinesias) are considered responsible for the failure of these therapies. Further, none of the treatments, alone or in combination, are capable of halting the disease progression in the long run. Therefore, there is a need to develop safe and efficient neuroprotective agents, which can slow or stop the disease progression for the better management of PD. In this review, an effort has been made to discuss the various mechanisms responsible for progressive neurodegeneration (disease progression) in PD and also multiple strategies available for halting disease progression.

Differences in Tau Seeding in Newborn and Adult Wild-Type Mice

Alzheimer's disease (AD) and other tauopathies are common neurodegenerative diseases in older adults; in contrast, abnormal tau deposition in neurons and glial cells occurs only exceptionally in children. Sarkosyl-insoluble fractions from sporadic AD (sAD) containing paired helical filaments (PHFs) were inoculated unilaterally into the thalamus in newborn and three-month-old wild-type C57BL/6 mice, which were killed at different intervals from 24 h to six months after inoculation. Tau-positive cells were scanty and practically disappeared at three months in mice inoculated at the age of a newborn. In contrast, large numbers of tau-positive cells, including neurons and oligodendrocytes, were found in the thalamus of mice inoculated at three months and killed at the ages of six months and nine months. Mice inoculated at the age of newborn and re-inoculated at the age of three months showed similar numbers and distribution of positive cells in the thalamus at six months and nine months. This study shows that (a) differences in tau seeding between newborn and young adults may be related to the ratios between 3Rtau and 4Rtau, and the shift to 4Rtau predominance in adults, together with the immaturity of connections in newborn mice, and (b) intracerebral inoculation of sAD PHFs in newborn mice does not protect from tau seeding following intracerebral inoculation of sAD PHFs in young/adult mice.

Environmentally Toxic Solid Nanoparticles in Noradrenergic and Dopaminergic Nuclei and Cerebellum of Metropolitan Mexico City Children and Young Adults with Neural Quadruple Misfolded Protein Pathologies and High Exposures to Nano Particulate Matter

Quadruple aberrant hyperphosphorylated tau, beta-amyloid, α-synuclein and TDP-43 neuropathology and metal solid nanoparticles (NPs) are documented in the brains of children and young adults exposed to Metropolitan Mexico City (MMC) pollution. We investigated environmental NPs reaching noradrenergic and dopaminergic nuclei and the cerebellum and their associated ultrastructural alterations. Here, we identify NPs in the locus coeruleus (LC), substantia nigrae (SN) and cerebellum by transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometry (EDX) in 197 samples from 179 MMC residents, aged 25.9 ± 9.2 years and seven older adults aged 63 ± 14.5 years. Fe, Ti, Hg, W, Al and Zn spherical and acicular NPs were identified in the SN, LC and cerebellar neural and vascular mitochondria, endoplasmic reticulum, Golgi, neuromelanin, heterochromatin and nuclear pore complexes (NPCs) along with early and progressive neurovascular damage and cerebellar endothelial erythrophagocytosis. Strikingly, FeNPs 4 ± 1 nm and Hg NPs 8 ± 2 nm were seen predominantly in the LC and SN. Nanoparticles could serve as a common denominator for misfolded proteins and could play a role in altering and obstructing NPCs. The NPs/carbon monoxide correlation is potentially useful for evaluating early neurodegeneration risk in urbanites. Early life NP exposures pose high risk to brains for development of lethal neurologic outcomes. NP emissions sources ought to be clearly recognized, regulated, and monitored; future generations are at stake.

Review of evidence implicating the plasminogen activator system in blood-brain barrier dysfunction associated with Alzheimer's disease

Elucidating the pathogenic mechanisms of Alzheimer’s disease (AD) to identify therapeutic targets has been the focus of many decades of research. While deposition of extracellular amyloid-beta plaques and intraneuronal neurofibrillary tangles of hyperphosphorylated tau have historically been the two characteristic hallmarks of AD pathology, therapeutic strategies targeting these proteinopathies have not been successful in the clinics. Neuroinflammation has been gaining more attention as a therapeutic target because increasing evidence implicates neuroinflammation as a key factor in the early onset of AD disease progression. The peripheral immune response has emerged as an important contributor to the chronic neuroinflammation associated with AD pathophysiology. In this context, the plasminogen activator system (PAS), also referred to as the vasculature’s fibrinolytic system, is emerging as a potential factor in AD pathogenesis. Evolving evidence suggests that the PAS plays a role in linking chronic peripheral inflammatory conditions to neuroinflammation in the brain. While the PAS is better known for its peripheral functions, components of the PAS are expressed in the brain and have been demonstrated to alter neuroinflammation and blood-brain barrier (BBB) permeation. Here, we review plasmin-dependent and -independent mechanisms by which the PAS modulates the BBB in AD pathogenesis and discuss therapeutic implications of these observations.

Neuroimaging and biomarker evidence of neurodegeneration in asthma

BACKGROUND

Epidemiologic studies have shown that Alzheimer's disease (AD) and related dementias (ADRD) are seen more frequently with asthma, especially with greater asthma severity or exacerbation frequency.

OBJECTIVE

To examine the changes in brain structure that may underlie this phenomenon, we examined diffusion-weighted magnetic resonance imaging (dMRI) and blood-based biomarkers of AD (phosphorylated tau 181, p-Tau181), neurodegeneration (neurofilament light chain, NfL), and glial activation (glial fibrillary acidic protein, GFAP).

METHODS

dMRI data were obtained in 111 individuals with asthma, ranging in disease severity from mild to severe, and 135 healthy controls. Regression analyses were used to test the relationships between asthma severity and neuroimaging measures, as well as AD pathology, neurodegeneration, and glial activation, indexed by plasma p-Tau181, NfL, and GFAP, respectively. Additional relationships were tested with cognitive function.

RESULTS

Asthma participants had widespread and large-magnitude differences in several dMRI metrics, which were indicative of neuroinflammation and neurodegeneration, and which were robustly associated with GFAP and, to a lesser extent, NfL. The AD biomarker p-Tau181 was only minimally associated with neuroimaging outcomes. Further, asthma severity was associated with deleterious changes in neuroimaging outcomes, which in turn were associated with slower processing speed, a test of cognitive performance.

CONCLUSIONS

Asthma, particularly when severe, is associated with characteristics of neuroinflammation and neurodegeneration, and may be a potential risk factor for neural injury and cognitive dysfunction. There is a need to determine how asthma may affect brain health and whether treatment directed toward characteristics of asthma associated with these risks can mitigate these effects.

Early environmental exposures and life-long risk of chronic non-respiratory disease

Exposure to environmental hazards occurs from the earliest stages of development. There are a broad range of environmental hazards, and virtually all children are exposed to these hazards during the critical period of growth and development. The burden of many chronic diseases continues to rise, and life course studies have shown that early exposure to environmental hazards is associated with non-communicable disease in later years. This review will discuss the environmental exposures associated with four non-respiratory chronic diseases: obesity, diabetes, cardiovascular disease and neurodevelopmental /neurodegenerative conditions.

Effect of carbon nanomaterial dimension on the functional activity and degeneration of neurons

Despite growing concerns regarding the threat of airborne nanoparticle-mediated brain degeneration, the underlying pathological mechanisms remain unclear. Carbon nanomaterials, the main components of airborne nanoparticles, have multi-dimensional structures. Therefore, the dimensional effect of carbon-based nanomaterials on the regulation of neural function in brain disorders requires additional clarification. Herein, we report the interaction between zero-to three-dimensional carbon nanostructures and the amyloid-beta protein, which can either activate or interrupt neuronal functions, depending on the dimension of the carbon nanostructures. The carbon nanomaterials induced significant cellular activation by short-term exposure, while prolonged exposure eventually caused neuronal cell death. Such dimension-dependent activation or degeneration was more evident in the higher-dimension carbon nanomaterials, as confirmed by the increases in neurotransmitter secretion and synapse-related protein levels to more than five times at 72 h of monitoring and calcium signaling in the neurons. The inclusion of amyloid-beta proteins ameliorated the cytotoxic effects of carbon nanomaterials in higher-dimensional carbon nanomaterials by regulating 333 genes. We found that the ɑ-synuclein gene is the key factor in carbon-induced abnormal neuronal function. Therefore, through biological analyses and in vitro feasibility studies, this new insight may contribute toward understanding the pathological mechanism and finding a new target for therapy in human brain pathologies.

Exposure to low-dose ambient fine particulate matter PM2.5 and Alzheimer's disease, non-Alzheimer's dementia, and Parkinson's disease in North Carolina

Alzheimer's disease (AD), non-AD dementia, and Parkinson's disease (PD) are increasingly common in older adults, yet all risk factors for their onset are not fully understood. Consequently, environmental exposures, including air pollution, have been hypothesized to contribute to the etiology of neurodegeneration. Because persistently elevated rates of AD mortality in the southern Piedmont area of North Carolina (NC) have been documented, we studied mortality and hospital admissions for AD, non-AD dementia, and PD in residential populations aged 65+ with long-term exposures to elevated levels of ambient air particulate matter 2.5 (PM2.5) exceeding the World Health Organization (WHO) air quality standards (≥10μg/m3). Health data were obtained from the State Center for Health Statistics and the Healthcare Cost and Utilization Project. PM2.5 levels were obtained from the MODIS/MISR and SeaWiFS datafiles. Residents in the Study group of elevated air particulate matter (87 zip codes with PM2.5≥10μg/m3) were compared to the residents in the Control group with low levels of air particulate matter (81 zip codes with PM2.5≤7.61μg/m3), and were found to have higher age-adjusted rates of mortality and hospital admissions for AD, non-AD dementia, and PD, including a most pronounced increase in AD mortality (323/100,000 vs. 257/100,000, respectively). After adjustment for multiple co-factors, the risk of death (odds ratio, or OR) from AD in the Study group (OR = 1.35, 95%CI[1.24-1.48]) was significantly higher than ORs of non-AD dementia or PD (OR = 0.97, 95%CI[0.90-1.04] and OR = 1.13, 95%CI[0.92-1.31]). The OR of hospital admissions was significantly increased only for AD as a primary case of hospitalization (OR = 1.54, 95%CI[1.31-1.82]). Conclusion: NC residents aged 65+ with long-term exposures to ambient PM2.5 levels exceeding the WHO standard had significantly increased risks of death and hospital admissions for AD. The effects for non-AD dementia and PD were less pronounced.

Brain correlates of urban environmental exposures in cognitively unimpaired individuals at increased risk for Alzheimer's disease: A study on Barcelona's population

INTRODUCTION

Urban environmental exposures might contribute to the incidence of Alzheimer's disease (AD). Our aim was to identify structural brain imaging correlates of urban environmental exposures in cognitively unimpaired individuals at increased risk of AD.

METHODS

Two hundred twelve participants with brain scans and residing in Barcelona, Spain, were included. Land use regression models were used to estimate residential exposure to air pollutants. The daily average noise level was obtained from noise maps. Residential green exposure indicators were also generated. A cerebral 3D-T1 was acquired to obtain information on brain morphology. Voxel-based morphometry statistical analyses were conducted to determine the areas of the brain in which regional gray matter (GM) and white matter (WM) volumes were associated with environmental exposures.

RESULTS

Exposure to nitrogen dioxide was associated with lower GM volume in the precuneus and greater WM volume in the splenium of the corpus callosum and inferior longitudinal fasciculus. In contrast, exposure to fine particulate matter was associated with greater GM in cerebellum and WM in the splenium of corpus callosum, the superior longitudinal fasciculus, and cingulum cingulate gyrus. Noise was positively associated with WM volume in the body of the corpus callosum. Exposure to greenness was associated with greater GM volume in the middle frontal, precentral, and the temporal pole.

DISCUSSION

In cognitively unimpaired adults with increased risk of AD, exposure to air pollution, noise, and green areas are associated with GM and WM volumes of specific brain areas known to be affected in AD, thus potentially conferring a higher vulnerability to the disease.

Ameliorative Role of Nutraceuticals on Neurodegenerative Diseases Using the Drosophila melanogaster as a Discovery Model to Define Bioefficacy

Neurodegeneration is the destruction of neurons, and once the neurons degenerate they can't revive. This is one of the most concerned health conditions among aged population, more than ∼70% of the elderly people are suffering from neurodegeneration. Among all of the neurodegenerative diseases, Alzheimer's disease (AD), Parkinson's disease (PD) and Poly-glutamine disease (Poly-Q) are the major one and affecting most of the people around the world and posing excessive burden on the society. In order to understand this disease in non-human animal models it is pertinent to examine in model organism and various animal model are being used for such diseases like rat, mice and non-vertebrate model like Drosophila. Drosophila melanogaster is one of the best animal proven by several eminent scientist and had received several Nobel prizes for uncovering mechanism of human related genes and highly efficient model for studying neurodegenerative diseases due to its great affinity with human disease-related genes. Another factor is also employed to act as therapeutic or preventive method that is nutraceuticals. Nutraceuticals are functional natural compounds with antioxidant properties and had extensively showed the neuroprotective effect in different organisms. These nutraceuticals having antioxidant properties act through scavenging free radicals or by increasing endogenous cellular antioxidant defense molecules. For the best benefit, we are trying to utilize these nutraceuticals, which will have no or negligible side effects. In this review, we are dealing with various types of such nutraceuticals which have potent value in the prevention and curing of the diseases related to neurodegeneration.HighlightsNeurodegeneration is the silently progressing disease which shows its symptoms when it is well rooted.Many chemical drugs (almost all) have only symptomatic relief with side effects.Potent mechanism of neurodegeneration and improvement effect by nutraceuticals is proposed.Based on the Indian Cuisine scientists are trying to find the medicine from the food or food components having antioxidant properties.The best model to study the neurodegenerative diseases is Drosophila melanogaster.Many nutraceuticals having antioxidant properties have been studied and attenuated various diseases are discussed.

An impact of air pollution on moderate to severe relapses among multiple sclerosis patients

BACKGROUND

Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system with both a genetic and environmental component.

OBJECTIVE

In the current study, we examined an association between incidence of MS moderate to severe relapses and exposure to air pollutants and meteorological exposures.

METHODS

We enrolled MS patients in Southern Israel during 2000-2017. Exposure assessment relied on satellite-based model of exposure to particulate matter of size <2.5 and 10 microns (PM_2.5, PM₁₀) and temperature at a spatial resolution of 1 km (Kloog et al., 2015). The information on exposure to nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ozone (O₃) levels was completed from the database of the monitoring stations. We analyzed the data using a semi-ecological approach. The monthly incidence of MS-related relapses requiring hospitalization as a function of environmental factors was analyzed by time-series technique, adjusting to sex, age and smoking. We also used a case-crossover approach to compare environmental exposure of a patient on the day of the relapse with the exposure on the relapse-free days. All estimates were adjusted to the heat index and were divided by IQR.

RESULTS

There were 287 MS patients in the study, with an average age of 52.8 ± 16.7 years, 37% of them (107) being under 40. Mostly female (66.2%), and 13.6% of the patients smoking (47% non-smoking and 39.4% unknown). PM_2.5 was independently associated with MS relapses within the non-smoking population [Relative Risk (RR)=1.28, 95%CI:1.01-1.62]. O₃ was found adversely associated with MS relapses among patients younger than 40 [RR=1.58, 95%CI 1.03-4.43]. Based on the case-crossover approach, relapses were associated with elevated levels of PM₁₀ and NO₂ in all subjects [Odds Ratio (OR)=1.05, 95%CI:1.00-1.11; OR=1.85, 95%CI: 1.28-2.68, respectively]. An adverse association with PM_2.5 was observed in non-smokers [OR 1.12, 95%CI 1.00-1.25].

CONCLUSIONS

The findings show that MS relapses are adversely associated with an ambient exposure to PM and NO₂.

A critical review of the epidemiological evidence of effects of air pollution on dementia, cognitive function and cognitive decline in adult population

Dementia is arguably the most pressing public health challenge of our age. Since dementia does not have a cure, identifying risk factors that can be controlled has become paramount to reduce the personal, societal and economic burden of dementia. The relationship between exposure to air pollution and effects on cognitive function, cognitive decline and dementia has stimulated increasing scientific interest in the past few years. This review of the literature critically examines the available epidemiological evidence of associations between exposure to ambient air pollutants, cognitive performance, acceleration of cognitive decline, risk of developing dementia, neuroimaging and neurological biomarker studies, following Bradford Hill guidelines for causality. The evidence reviewed has been consistent in reporting associations between chronic exposure to air pollution and reduced global cognition, as well as impairment in specific cognitive domains including visuo-spatial abilities. Cognitive decline and dementia incidence have also been consistently associated with exposure to air pollution. The neuro-imaging studies reviewed report associations between exposure to air pollution and white matter volume reduction. Other reported effects include reduction in gray matter, larger ventricular volume, and smaller corpus callosum. Findings relating to ischemic (white matter hyperintensities/silent cerebral infarcts) and hemorrhagic (cerebral microbleeds) markers of cerebral small vessel disease have been heterogeneous, as have observations on hippocampal volume and air pollution. The few studies available on neuro-inflammation tend to report associations with exposure to air pollution. Several effect modifiers have been suggested in the literature, but more replication studies are required. Traditional confounding factors have been controlled or adjusted for in most of the reviewed studies. Additional confounding factors have also been considered, but the inclusion of these has varied among the different studies. Despite all the efforts to adjust for confounding factors, residual confounding cannot be completely ruled out, especially since the factors affecting cognition and dementia are not yet fully understood. The available evidence meets many of the Bradford Hill guidelines for causality. The reported associations between a range of air pollutants and effects on cognitive function in older people, including the acceleration of cognitive decline and the induction of dementia, are likely to be causal in nature. However, the diversity of study designs, air pollutants and endpoints examined precludes the attribution of these adverse effects to a single class of pollutant and makes meta-analysis inappropriate.

The Impact of Air Pollution on Neurodegenerative Diseases

BACKGROUND

With the development of industrialization in human society, ambient pollutants are becoming more harmful to human health. Epidemiological and toxicological studies indicate that a close relationship exists between particulate matter with a diameter ≤2.5 µm (PM2.5) and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). To further confirm the relationship, we focus on possible relevant mechanisms of oxidative stress and neuroinflammation underlying the association between PM2.5 and neurodegenerative diseases in the review.

METHODS

A literature search was performed on the studies about PM2.5 and neurodegenerative diseases via PubMed. A total of 113 articles published were selected, and 31 studies were included.

RESULTS

PM2.5 can enter the central nervous system through 2 main pathways, the blood-brain barrier and olfactory neurons. The inflammatory response and oxidative stress are 2 primary mechanisms via which PM2.5 leads to toxicity in the brain. PM2.5 abnormally activates microglia, inducing the neuroinflammatory process. Inflammatory markers such as IL-1β play an essential role in neurodegenerative diseases such as AD and PD. Moreover, the association between lipid mechanism disorders related to PM2.5 and neurodegenerative diseases has been gaining momentum.

CONCLUSIONS

In conclusion, PM2.5 could significantly increase the risk of neurological disorders, such as AD and PD. Furthermore, any policy aimed at reducing air-polluting emissions and increasing air quality would be protective in human beings.

Chinese nutraceuticals and physical activity; their role in neurodegenerative tauopathies

The onset of neurodegenerative disease has not only been a major cause of scientific worry, but of economic burden to the health system. This condition has been further attributed to mis-stability, deletion or mutation of tau protein, causing the onset of Corticobasal degeneration, Pick's diseases, Progressive supranuclear palsy, Argyrophilic grains disease, Alzheimer's diseases etc. as scientifically renowned. This is mainly related to dysregulation of translational machinery, upregulation of proinflammatory cytokines and inhibition of several essential cascades such as ERK signaling cascade, GSK3β, CREB, and PKA/PKB (Akt) signaling cascades that enhances protein processing, normal protein folding, cognitive function, and microtubule associated tau stability. Administration of some nutrients and/or bioactive compounds has a high tendency to impede tau mediated inflammation at neuronal level. Furthermore, prevention and neutralization of protein misfolding through modulation of microtubule tau stability and prevention of protein misfolding is by virtue few of the numerous beneficial effects of physical activity. Of utmost important in this study is the exploration of promising bioactivities of nutraceuticals found in china and the ameliorating potential of physical activity on tauopathies, while highlighting animal and in vitro studies that have been investigated for comprehensive understanding of its potential and an insight into the effects on human highly probable to tau mediated neurodegeneration.

Is Environmental and Occupational Particulate Air Pollution Exposure Related to Type-2 Diabetes and Dementia? A Cross-Sectional Analysis of the UK Biobank

Human exposure to particulate air pollution (e.g., PM_2.5) can lead to adverse health effects, with compelling evidence that it can increase morbidity and mortality from respiratory and cardiovascular disease. More recently, there has also been evidence that long-term environmental exposure to particulate air pollution is associated with type-2 diabetes mellitus (T2DM) and dementia. There are many occupations that may expose workers to airborne particles and that some exposures in the workplace are very similar to environmental particulate pollution. We conducted a cross-sectional analysis of the UK Biobank cohort to verify the association between environmental particulate air pollution (PM_2.5) exposure and T2DM and dementia, and to investigate if occupational exposure to particulates that are similar to those found in environmental air pollution could increase the odds of developing these diseases. The UK Biobank dataset comprises of over 500,000 participants from all over the UK. Environmental exposure variables were used from the UK Biobank. To estimate occupational exposure both the UK Biobank’s data and information from a job exposure matrix, specifically developed for UK Biobank (Airborne Chemical Exposure–Job Exposure Matrix (ACE JEM)), were used. The outcome measures were participants with T2DM and dementia. In appropriately adjusted models, environmental exposure to PM_2.5 was associated with an odds ratio (OR) of 1.02 (95% CI 1.00 to 1.03) per unit exposure for developing T2DM, while PM_2.5 was associated with an odds ratio of 1.06 (95% CI 0.96 to 1.16) per unit exposure for developing dementia. These environmental results align with existing findings in the published literature. Five occupational exposures (dust, fumes, diesel, mineral, and biological dust in the most recent job estimated with the ACE JEM) were investigated and the risks for most exposures for T2DM and for all the exposures for dementia were not significantly increased in the adjusted models. This was confirmed in a subgroup of participants where a full occupational history was available allowed an estimate of workplace exposures. However, when not adjusting for gender, some of the associations become significant, which suggests that there might be a bias between the occupational assessments for men and women. The results of the present study do not provide clear evidence of an association between occupational exposure to particulate matter and T2DM or dementia.

Effect of Severe External Airborne Agents' Exposure on Dementia

The impact of occupational and environmental exposure to external airborne agents on cognitive function, especially in incidence of dementia, is understudied. The present study was conducted to elucidate the association between severe external airborne agents' exposure and incidence of dementia among an elderly population and to explore the effects of exposure to severe external airborne agents on preclinical dementia using the screening test of dementia. From the National Health Insurance Service-Health Screening Cohort (NHIS-HealS, 2002-2015), 514,580 participants were used for data analysis. We estimated the standardized incidence ratio (SIR) according to the exposure to external airborne agents. Of the total participants (n = 514,580), 1340 (0.3%) experienced severe external airborne agents exposure, and 26,050 (5.1%) had been diagnosed with dementia. The SIRs (95%CI) of dementia in Alzheimer's disease, vascular dementia, dementia in other diseases, and unspecific dementia were 1.24 (1.01-1.49), 0.88 (0.37-1.32), 1.16 (0.01-2.77), and 0.69 (0.36-1.02), respectively. The risk of testing positive in the dementia screening significantly increased with exposure to severe external airborne agents after adjusting for all confounding variables. This study found that exposure to severe external airborne agents is a potential risk factor for dementia, especially in Alzheimer's disease. It is essential to create international awareness regarding the effect of airborne agents' exposure on dementia.

Developmental exposure to diesel exhaust upregulates transcription factor expression, decreases hippocampal neurogenesis, and alters cortical lamina organization: relevance to neurodevelopmental disorders

Background

Exposure to traffic-related air pollution (TRAP) during development and/or in adulthood has been associated in many human studies with both neurodevelopmental and neurodegenerative diseases, such as autism spectrum disorder (ASD) and Alzheimer’s disease (AD) or Parkinson’s disease (PD).

Methods

In the present study, C57BL/6 J mice were exposed to environmentally relevant levels (250+/−50 μg/m³) of diesel exhaust (DE) or filtered air (FA) during development (E0 to PND21). The expression of several transcription factors relevant for CNS development was assessed on PND3. To address possible mechanistic underpinnings of previously observed behavioral effects of DE exposure, adult neurogenesis in the hippocampus and laminar organization of neurons in the somatosensory cortex were analyzed on PND60. Results were analyzed separately for male and female mice.

Results

Developmental DE exposure caused a male-specific upregulation of Pax6, Tbr1, Tbr2, Sp1, and Creb1 on PND3. In contrast, in both males and females, Tbr2⁺ intermediate progenitor cells in the PND60 hippocampal dentate gyrus were decreased, as an indication of reduced adult neurogenesis. In the somatosensory region of the cerebral cortex, laminar distribution of Trb1, calbindin, and parvalbumin (but not of Ctip2 or Cux1) was altered by developmental DE exposure.

Conclusions

These results provide additional evidence to previous findings indicating the ability of developmental DE exposure to cause biochemical/molecular and behavioral alterations that may be involved in neurodevelopmental disorders such as ASD.

Role of environmental pollutants in Alzheimer's disease: a review

Neurodegenerative disorders are commonly erratic influenced by various factors including lifestyle, environmental, and genetic factors. In recent observations, it has been hypothesized that exposure to various environmental factors enhances the risk of Alzheimer's disease (AD). The exact etiology of Alzheimer's disease is still unclear; however, the contribution of environmental factors in the pathology of AD is widely acknowledged. Based on the available literature, the review aims to culminate in the prospective correlation between the various environmental factors and AD. The prolonged exposure to the various well-known environmental factors including heavy metals, air pollutants (particulate matter), pesticides, nanoparticles containing metals, industrial chemicals results in accelerating the progression of AD. Common mechanisms have been documented in the field of environmental contaminants for enhancing amyloid-β (Aβ) peptide along with tau phosphorylation, resulting in the initiation of senile plaques and neurofibrillary tangles, which results in the death of neurons. This review offers a compilation of available data to support the long-suspected correlation between environmental risk factors and AD pathology. Graphical abstract .

Environmental Nanoparticles, SARS-CoV-2 Brain Involvement, and Potential Acceleration of Alzheimer's and Parkinson's Diseases in Young Urbanites Exposed to Air Pollution

Alzheimer's and Parkinson's diseases (AD, PD) have a pediatric and young adult onset in Metropolitan Mexico City (MMC). The SARS-CoV-2 neurotropic RNA virus is triggering neurological complications and deep concern regarding acceleration of neuroinflammatory and neurodegenerative processes already in progress. This review, based on our MMC experience, will discuss two major issues: 1) why residents chronically exposed to air pollution are likely to be more susceptible to SARS-CoV-2 systemic and brain effects and 2) why young people with AD and PD already in progress will accelerate neurodegenerative processes. Secondary mental consequences of social distancing and isolation, fear, financial insecurity, violence, poor health support, and lack of understanding of the complex crisis are expected in MMC residents infected or free of SARS-CoV-2. MMC residents with pre-SARS-CoV-2 accumulation of misfolded proteins diagnostic of AD and PD and metal-rich, magnetic nanoparticles damaging key neural organelles are an ideal host for neurotropic SARS-CoV-2 RNA virus invading the body through the same portals damaged by nanoparticles: nasal olfactory epithelium, the gastrointestinal tract, and the alveolar-capillary portal. We urgently need MMC multicenter retrospective-prospective neurological and psychiatric population follow-up and intervention strategies in place in case of acceleration of neurodegenerative processes, increased risk of suicide, and mental disease worsening. Identification of vulnerable populations and continuous effort to lower air pollution ought to be critical steps.

Evaluation of the Suitability of an Existing Job-Exposure Matrix for the Assessment of Exposure of UK Biobank Participants to Dust, Fumes, and Diesel Exhaust Particulates

Many epidemiological studies have shown an association between outdoor particulate air pollutants and increased morbidity and mortality. Inhalation of ambient aerosols can exacerbate or promote the development of cardiovascular and pulmonary diseases as well as other diseases, such as type 2 diabetes mellitus (T2DM) and neurodegenerative diseases. Occupational exposure to dust, fumes and diesel exhaust particulates can also cause adverse health outcomes and there are numerous occupations where workers are exposed to airborne particles that are similar to ambient air pollution. An individual’s job title has normally been identified as a major determinant of workplace exposure in epidemiological studies. This has led to the development of Job–Exposure Matrices (JEMs) as a way of characterising specific workplace exposures. One JEM for airborne chemical exposures is the Airborne Chemical Exposure Job–Exposure Matrix (ACE JEM), developed specifically for the UK Biobank cohort. The objective of this paper is to evaluate the suitability of the ACE JEM in assessing occupational aerosol exposure of participants in the UK Biobank. We searched the scientific literature to identify exposure data linked to selected jobs in the ACE JEM and compared these data with the JEM assessments. Additionally, we carried out an independent expert-based assessment of exposure to compare with the JEM estimates. There is good published evidence to substantiate the high dust and biological dust assignments in the JEM and more limited evidence for diesel exhaust particulates. There is limited evidence in the published literature to substantiate moderate or low exposure assignments in the JEM. The independent expert-based assessment found good agreement at the two extremes of exposure in the JEM (high and no exposure), with uncertainty in all other classifications. The ACE JEM assignments are probably reliable for highly exposed jobs and for jobs assigned as unexposed. However, the assignments for medium and low exposures are less reliable. The ACE JEM is likely to be a good tool to examine associations between occupational exposures to particulates and chronic disease, although it should be used with caution. Further efforts should be made to improve the reliability of the ACE JEM.

Effect of long-term particulate matter exposure on Parkinson's risk

Environmental pollution is a critical predisposing factor underlying neurodegenerative diseases, but the association between particulate matter (PM) exposure and Parkinson's disease (PD) remains unclear. This study aimed to evaluate the association between long-term PM2.5/PM10 exposure and PD risk. We searched the PubMed, Ovid Medline, EMBASE, Cochrane Library, and Web of Science citation databases to select studies about the relationship between long-term PM exposure and PD risk. The association was assessed using meta-analysis, and subgroup analysis was carried out on the basis of the types of PM (PM2.5 and PM10). Among the 611 articles identified from the databases, we selected six articles, including three cohort studies and three case-control studies, which collectively involved 10,077,029 participants. With every 10 μg/m³ increment, the relative risks (RRs) and 95% confidence intervals (CIs) were 1.03 (0.98, 1.07), 1.21 (0.95, 1.54), and 1.01 (0.97, 1.05) for the total PM, PM2.5, and PM10, respectively. In the current study, no statistically substantial association was observed between long-term PM2.5/PM10 exposure and PD incidence. However, further large-scale prospective studies are needed to determine the association.

Gaseous Pollutants and Particulate Matter (PM) in Ambient Air and the Number of New Cases of Type 1 Diabetes in Children and Adolescents in the Pomeranian Voivodeship, Poland

The increase in type 1 diabetes mellitus (T1DM) incidence in children is worrying and not yet fully explored. It is suggested that probably air pollution exposure could contribute to the development of T1DM. The aim of the study was to investigate the relationship between the concentration of gaseous pollutants including, nitrogen dioxide (NO₂), nitric oxides (NOx), sulphur dioxide (SO₂), carbon monoxide (CO), and particulate matter (PM) in the air, and the number of new cases of T1DM in children. The number of new cases of T1DM was obtained from the Clinic of Paediatrics, Diabetology, and Endocrinology, Medical University of Gdańsk. The number of children of 0-18 years old in Pomeranian Voivodeship was acquired from the Statistical Yearbook. The concentrations of PM₁₀ absorbance, NO₂, NOx, SO₂, and CO were measured at 41 measuring posts, between 1 January 2015 and 31 December 2016. It was detected that the average annual concentration of PM₁₀ was higher than the value acceptable to the WHO. Furthermore, the average 24-hour concentration of PM₁₀ was 92 μg/m³ and was higher compared to the acceptable value of 50 μg/m³ (acc. to EU and WHO). Moreover, the number of new cases of T1DM showed a correlation with the annual average concentration of PM₁₀ (β = 2.396, p < 0.001), SO₂ (β = 2.294, p < 0.001), and CO (β = 2.452, p < 0.001). High exposure to gaseous pollutants and particulate matter in ambient air may be one of the factors contributing to the risk of developing T1DM in children. Therefore, it is important to take action to decrease air pollutant emissions in Poland. It is crucial to gradually but consistently eliminate the use of solid fuels, such as coal and wood in households, in favour of natural gas and electricity. The development of new technologies to improve air quality, such as "best available techniques" (BAT) or renewable energy sources (water, wind, and solar generation) is of critical importance as well.

Non-Phosphorylated Tau in Cerebrospinal Fluid is a Marker of Alzheimer's Disease Continuum in Young Urbanites Exposed to Air Pollution

Long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above USEPA standards is associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) children exhibit subcortical pretangles in infancy and cortical tau pre-tangles, NFTs, and amyloid phases 1-2 by the 2nd decade. Given their AD continuum, we measured in 507 normal cerebrospinal fluid (CSF) samples (MMC 354, controls 153, 12.82±6.73 y), a high affinity monoclonal non-phosphorylated tau antibody (non-P-Tau), as a potential biomarker of AD and axonal damage. In 81 samples, we also measured total tau (T-Tau), tau phosphorylated at threonine 181 (P-Tau), amyloid-β1-42, BDNF, and vitamin D. We documented by electron microscopy myelinated axonal size and the pathology associated with combustion-derived nanoparticles (CDNPs) in anterior cingulate cortex white matter in 6 young residents (16.25±3.34 y). Non-P-Tau showed a strong increase with age significantly faster among MMC versus controls (p = 0.0055). Aβ1 - 42 and BDNF concentrations were lower in MMC children (p = 0.002 and 0.03, respectively). Anterior cingulate cortex showed a significant decrease (p = <0.0001) in the average axonal size and CDNPs were associated with organelle pathology. Significant age increases in non-P-Tau support tau changes early in a population with axonal pathology and evolving AD hallmarks in the first two decades of life. Non-P-Tau is an early biomarker of axonal damage and potentially valuable to monitor progressive longitudinal changes along with AD multianalyte classical CSF markers. Neuroprotection of young urbanites with PM2.5 and CDNPs exposures ought to be a public health priority to halt the development of AD in the first two decades of life.

Increased Dementia Mortality in West Virginia Counties with Mountaintop Removal Mining?

Atmospheric particulate matter (PM) is elevated in areas of mountaintop removal mining (MTM), a practice that has been ongoing in some counties of West Virginia (WV) USA since the 1970s. PM inhalation has been linked to central nervous system pathophysiology, including cognitive decline and dementia. Here we compared county dementia mortality statistics in MTM vs. non-MTM WV counties over a period spanning 2001–2015. We found significantly elevated age-adjusted vascular or unspecified dementia mortality/100,000 population in WV MTM counties where, after adjusting for socioeconomic variables, dementia mortality was 15.60 (±3.14 Standard Error of the Mean (S.E.M.)) times higher than that of non-MTM counties. Further analyses with satellite imaging data revealed a highly significant positive correlation between the number of distinct mining sites vs. both mean and cumulative vascular and unspecified dementia mortality over the 15 year period. This was in contrast to finding only a weak relationship between dementia mortality rates and the overall square kilometers mined. No effect of living in an MTM county was found for the rate of Alzheimer’s type dementia and possible reasons for this are considered. Based on these results, and the current literature, we hypothesize that inhalation of PM associated with MTM contributes to dementia mortality of the vascular or unspecified types. However, limitations inherent in ecological-type studies such as this, preclude definitive extrapolation to individuals in MTM-counties at this time. We hope these findings will inspire follow-up cohort and case-controlled type studies to determine if specific causative factors associated with living near MTM can be identified. Given the need for caregiving and medical support, increased dementia mortality of the magnitude seen here could, unfortunately, place great demands upon MTM county public health resources in the future.

Airborne Particulate Matter: Human Exposure and Health Effects

OBJECTIVE

Exposure to airborne particulate matter (PM) is estimated to cause millions of premature deaths annually. This work conveys known routes of exposure to PM and resultant health effects.

METHODS

A review of available literature.

RESULTS

Estimates for daily PM exposure are provided. Known mechanisms by which insoluble particles are transported and removed from the body are discussed. Biological effects of PM, including immune response, cytotoxicity, and mutagenicity, are reported. Epidemiological studies that outline the systemic health effects of PM are presented.

CONCLUSION

While the integrated, per capita, exposure of PM for a large fraction of the first-world may be less than 1 mg per day, links between several syndromes, including attention deficit hyperactivity disorder (ADHD), autism, loss of cognitive function, anxiety, asthma, chronic obstructive pulmonary disease (COPD), hypertension, stroke, and PM exposure have been suggested. This article reviews and summarizes such links reported in the literature.

New Insights on the Role of Manganese in Alzheimer's Disease and Parkinson's Disease

Manganese (Mn) is an essential trace element that is naturally found in the environment and is necessary as a cofactor for many enzymes and is important in several physiological processes that support development, growth, and neuronal function. However, overexposure to Mn may induce neurotoxicity and may contribute to the development of Alzheimer's disease (AD) and Parkinson's disease (PD). The present review aims to provide new insights into the involvement of Mn in the etiology of AD and PD. Here, we discuss the critical role of Mn in the etiology of these disorders and provide a summary of the proposed mechanisms underlying Mn-induced neurodegeneration. In addition, we review some new therapy options for AD and PD related to Mn overload.

Combustion and friction-derived nanoparticles and industrial-sourced nanoparticles: The culprit of Alzheimer and Parkinson's diseases

Redox-active, strongly magnetic, combustion and friction-derived nanoparticles (CFDNPs) are abundant in particulate matter air pollution. Urban children and young adults with Alzheimer disease Continuum have higher numbers of brain CFDNPs versus clean air controls. CFDNPs surface charge, dynamic magnetic susceptibility, iron content and redox activity contribute to ROS generation, neurovascular unit (NVU), mitochondria, and endoplasmic reticulum (ER) damage, and are catalysts for protein misfolding, aggregation and fibrillation. CFDNPs respond to external magnetic fields and are involved in cell damage by agglomeration/clustering, magnetic rotation and/or hyperthermia. This review focus in the interaction of CFDNPs, nanomedicine and industrial NPs with biological systems and the impact of portals of entry, particle sizes, surface charge, biomolecular corona, biodistribution, mitochondrial dysfunction, cellular toxicity, anterograde and retrograde axonal transport, brain dysfunction and pathology. NPs toxicity information come from researchers synthetizing particles and improving their performance for drug delivery, drug targeting, magnetic resonance imaging and heat mediators for cancer therapy. Critical information includes how these NPs overcome all barriers, the NPs protein corona changes as they cross the NVU and the complexity of NPs interaction with soluble proteins and key organelles. Oxidative, ER and mitochondrial stress, and a faulty complex protein quality control are at the core of Alzheimer and Parkinson's diseases and NPs mechanisms of action and toxicity are strong candidates for early development and progression of both fatal diseases. Nanoparticle exposure regardless of sources carries a high risk for the developing brain homeostasis and ought to be included in the AD and PD research framework.

Repeated gestational exposure to diesel engine exhaust affects the fetal olfactory system and alters olfactory-based behavior in rabbit offspring

BACKGROUND

Airborne pollution, especially from diesel exhaust (DE), is known to have a negative effect on the central nervous system in exposed human populations. However, the consequences of gestational exposure to DE on the fetal brain remain poorly explored, with various effects depending on the conditions of exposure, as well as little information on early developmental stages. We investigated the short-term effects of indirect DE exposure throughout gestation on the developing brain using a rabbit model. We analyzed fetal olfactory tissues at the end of gestation and tested behaviors relevant to pups' survival at birth. Pregnant dams were exposed by nose-only inhalation to either clean air or DE with a content of particles (DEP) adjusted to 1 mg/m3 by diluting engine exhaust, for 2 h/day, 5 days/week, from gestational day 3 (GD3) to day 27 (GD27). At GD28, fetal olfactory mucosa, olfactory bulbs and whole brains were collected for anatomical and neurochemical measurements. At postnatal day 2 (PND2), pups born from another group of exposed or control female were examined for their odor-guided behavior in response to the presentation of the rabbit mammary pheromone 2-methyl-3-butyn-2-ol (2MB2).

RESULTS

At GD28, nano-sized particles were observed in cilia and cytoplasm of the olfactory sensory neurons in the olfactory mucosa and in the cytoplasm of periglomerular cells in the olfactory bulbs of exposed fetuses. Moreover, cellular and axonal hypertrophies were observed throughout olfactory tissues. Concomitantly, fetal serotoninergic and dopaminergic systems were affected in the olfactory bulbs. Moreover, the neuromodulatory homeostasis was disturbed in a sex-dependent manner in olfactory tissues. At birth, the olfactory sensitivity to 2MB2 was reduced in exposed PND2 pups.

CONCLUSION

Gestational exposure to DE alters olfactory tissues and affects monoaminergic neurotransmission in fetuses' olfactory bulbs, resulting in an alteration of olfactory-based behaviors at birth. Considering the anatomical and functional continuum between the olfactory system and other brain structures, and due to the importance of monoamine neurotransmission in the plasticity of neural circuits, such alterations could participate to disturbances in higher integrative structures, with possible long-term neurobehavioral consequences.

Association between ambient air pollution and Parkinson's disease: Systematic review and meta-analysis

Air pollution has been evaluated as a possible risk factor for Parkinson's disease (PD), but, the present results are inconsistent and have not been combined. We performed a systematic review and meta-analysis to estimate the association between long-term exposure to ambient air pollution and PD, given the nature of disease etiology. A total of 10 studies were identified by searching Web of Science, Science Direct, and PubMed before October 2017. We found a significantly increased risk of PD with 10 parts per billion (ppb) increase in nitrogen oxides (NO_x) exposure (relative risk (RR) = 1.06; 95% confidence interval (CI): 1.04, 1.09). The pooled RR for the association between carbon monoxide (CO) exposure, 1 parts per million (ppm) increment, and the risk of PD was 1.65 (95% CI: 1.10, 2.48). The pooled RRs for the association between nitrogen dioxide (NO₂) and ozone (O₃) exposure per 1 ppb increment, and the risk of PD were 1.01 (95% CI: 1.00, 1.03) and 1.01 (95% CI: 1.00, 1.02), respectively. There was a significant heterogeneity in the meta-analysis for fine particulate matter (PM_2.5), NO₂, sulfur dioxide (SO₂), and CO. We concluded that NO₂, NO_x, CO and O₃ exposure were associated with an increased risk of PD, although there is high risk of bias. The dose-response effects evaluated by high-quality studies are needed. Researches should be expanded to low- and/or middle- income countries where indoor and outdoor air pollution are high. CAPSULE: Long-term exposure to ambient NO₂, NO_x, CO and O₃ can increase the risk of Parkinson's disease.

Urban air pollution and climate change: "The Decalogue: Allergy Safe Tree" for allergic and respiratory diseases care

BACKGROUND

According to the World Health Organization, air pollution is closely associated with climate change and, in particular, with global warming. In addition to melting of ice and snow, rising sea level, and flooding of coastal areas, global warming is leading to a tropicalization of temperate marine ecosystems. Moreover, the effects of air pollution on airway and lung diseases are well documented as reported by the World Allergy Organization.

METHODS

Scientific literature was searched for studies investigating the effect of the interaction between air pollution and climate change on allergic and respiratory diseases.

RESULTS

Since 1990s, a multitude of articles and reviews have been published on this topic, with many studies confirming that the warming of our planet is caused by the "greenhouse effect" as a result of increased emission of "greenhouse" gases. Air pollution is also closely linked to global warming: the emission of hydrocarbon combustion products leads to increased concentrations of biological allergens such as pollens, generating a mixture of these particles called particulate matter (PM). The concept is that global warming is linked to the emission of hydrocarbon combustion products, since both carbon dioxide and heat increase pollen emission into the atmosphere, and all these particles make up PM10. However, the understanding of the mechanisms by which PM affects human health is still limited. Therefore, several studies are trying to determine the causes of global warming. There is also evidence that increased concentrations of air pollutants and pollens can activate inflammatory mediators in the airways. Our Task Force has prepared a Decalogue of rules addressing public administrators, which aims to limit the amount of allergenic pollen in the air without sacrificing public green areas.

CONCLUSIONS

Several studies underscore the significant risks of global warming on human health due to increasing levels of air pollution. The impact of climate change on respiratory diseases appears well documented. The last decades have seen a rise in the concentrations of pollens and pollutants in the air. This rise parallels the increase in the number of people presenting with allergic symptoms (e.g., allergic rhinitis, conjunctivitis, and asthma), who often require emergency medical care. Our hope is that scientists from different disciplines will work together with institutions, pharmaceutical companies and lay organizations to limit the adverse health effects of air pollution and global warming.

Exposure to Environmental and Occupational Particulate Air Pollution as a Potential Contributor to Neurodegeneration and Diabetes: A Systematic Review of Epidemiological Research

It has been hypothesised that environmental air pollution, especially airborne particles, is a risk factor for type 2 diabetes mellitus (T2DM) and neurodegenerative conditions. However, epidemiological evidence is inconsistent and has not been previously evaluated as part of a systematic review. Our objectives were to carry out a systematic review of the epidemiological evidence on the association between long-term exposure to ambient air pollution and T2DM and neurodegenerative diseases in adults and to identify if workplace exposures to particles are associated with an increased risk of T2DM and neurodegenerative diseases. Assessment of the quality of the evidence was carried out using the GRADE system, which considers the quality of the studies, consistency, directness, effect size, and publication bias. Available evidence indicates a consistent positive association between ambient air pollution and both T2DM and neurodegeneration risk, such as dementia and a general decline in cognition. However, corresponding evidence for workplace exposures are lacking. Further research is required to identify the link and mechanisms associated with particulate exposure and disease pathogenesis and to investigate the risks in occupational populations. Additional steps are needed to reduce air pollution levels and possibly also in the workplace environment to decrease the incidence of T2DM and cognitive decline.

Traffic-Related Air Pollution, APOEε4 Status, and Neurodevelopmental Outcomes among School Children Enrolled in the BREATHE Project (Catalonia, Spain)

BACKGROUND

Traffic-related air pollution is emerging as a risk factor for Alzheimer's disease (AD) and impaired brain development. Individual differences in vulnerability to air pollution may involve the ε4 allele of Apolipoprotein E (APOE) gene, the primary genetic risk factor for AD.

OBJECTIVE

We analyzed whether the association between traffic air pollution and neurodevelopmental outcomes is modified by APOEε4 status in children.

METHODS

Data on parent-reported behavior problems (total difficulties scores, Strengths and Difficulties Questionnaire), teacher-reported attention-deficit hyperactivity disorder (ADHD) symptom scores, cognitive performance trajectories (computerized tests of inattentiveness and working memory repeated 2-4 times during January 2012-March 2013), and APOE genotypes were obtained for 1,667 children age 7-11 y attending 39 schools in or near Barcelona. Basal ganglia volume (putamen, caudate, and globus pallidum) was measured in 163 of the children by MRI (October 2012-April 2014.) Average annual outdoor polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and nitrogen dioxide (NO2) concentrations were estimated based on measurements at each school (two 1-wk campaigns conducted 6 months apart in 2012).

RESULTS

APOEε4 allele carriers had significantly higher behavior problem scores than noncarriers, and adverse associations with PAHs and NO2 were stronger or limited to ε4 carriers for behavior problem scores (P-interaction 0.03 and 0.04), caudate volume (P-interaction 0.04 and 0.03), and inattentiveness trajectories (P-interaction 0.15 and 0.08, respectively). Patterns of associations with the same outcomes were similar for EC.

CONCLUSION

PAHs, EC, and NO2 were associated with higher behavior problem scores, smaller reductions in inattentiveness over time, and smaller caudate volume in APOEε4 allele carriers in our study population, and corresponding associations were weak or absent among ε4 noncarriers. These findings support a potential role of APOE in biological mechanisms that may contribute to associations between air pollution and neurobehavioral outcomes in children. https://doi.org/10.1289/EHP2246.

Severe Urban Outdoor Air Pollution and Children's Structural and Functional Brain Development, From Evidence to Precautionary Strategic Action

According to the latest estimates, about 2 billion children around the world are exposed to severe urban outdoor air pollution. Transdisciplinary, multi-method findings from epidemiology, developmental neuroscience, psychology, and pediatrics, show detrimental outcomes associated with pre- and postnatal exposure are found at all ages. Affected brain-related functions include perceptual and sensory information processing, intellectual and cognitive development, memory and executive functions, emotion and self-regulation, and academic achievement. Correspondingly, with the breakdown of natural barriers against entry and translocation of toxic particles in the brain, the most common structural changes are responses promoting neuroinflammation and indicating early neurodegenerative processes. In spite of the gaps in current scientific knowledge and the challenges posed by non-scientific issues that influence policy, the evidence invites the conclusion that urban outdoor air pollution is a serious threat to healthy brain development which may set the conditions for neurodegenerative diseases. Such evidence supports the perspective that urgent strategic precautionary actions, minimizing exposure and attenuating its effects, are needed to protect children and their brain development.

Neurodevelopmental and neurological effects of chemicals associated with unconventional oil and natural gas operations and their potential effects on infants and children

Heavy metals (arsenic and manganese), particulate matter (PM), benzene, toluene, ethylbenzene, xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs) and endocrine disrupting chemicals (EDCs) have been linked to significant neurodevelopmental health problems in infants, children and young adults. These substances are widely used in, or become byproducts of unconventional oil and natural gas (UOG) development and operations. Every stage of the UOG lifecycle, from well construction to extraction, operations, transportation and distribution can lead to air and water contamination. Residents near UOG operations can suffer from increased exposure to elevated concentrations of air and water pollutants. Here we focus on five air and water pollutants that have been associated with potentially permanent learning and neuropsychological deficits, neurodevelopmental disorders and neurological birth defects. Given the profound sensitivity of the developing brain and central nervous system, it is reasonable to conclude that young children who experience frequent exposure to these pollutants are at particularly high risk for chronic neurological diseases. More research is needed to understand the extent of these concerns in the context of UOG, but since UOG development has expanded rapidly in recent years, the need for public health prevention techniques, well-designed studies and stronger state and national regulatory standards is becoming increasingly apparent.

Microglial Immune Response to Low Concentrations of Combustion-Generated Nanoparticles: An In Vitro Model of Brain Health

The brain is the central regulator for integration and control of responses to environmental cues. Previous studies suggest that air pollution may directly impact brain health by triggering the onset of chronic neuroinflammation. We hypothesize that nanoparticle components of combustion-generated air pollution may underlie these effects. To test this association, a microglial in vitro biological sensor model was used for testing neuroinflammatory response caused by low-dose nanoparticle exposure. The model was first validated using 20 nm silver nanoparticles (AgNP). Next, neuroinflammatory response was tested after exposure to size-selected 20 nm combustion-generated nanoparticles (CGNP) collected from a modern diesel engine. We show that low concentrations of CGNPs promote low-grade inflammatory response indicated by increased pro-inflammatory cytokine release (tumor necrosis factor-α), similar to that observed after AgNP exposure. We also demonstrate increased production of reactive oxygen species and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 phosphorylation in microglia after CGNP stimulation. Finally, we show conditioned media from CGNP-stimulated microglia significantly reduced hypothalamic neuronal survival in vitro. To our knowledge, this data show for the first time that exposure to AgNP and CGNP elicits microglial neuroinflammatory response through the activation of NF-κB.

Cerebrospinal Fluid Biomarkers in Highly Exposed PM2.5 Urbanites: The Risk of Alzheimer's and Parkinson's Diseases in Young Mexico City Residents

Exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with Alzheimer's disease (AD) risk, while Mn toxicity induces parkinsonism. Mexico City Metropolitan Area (MCMA) children have pre- and postnatal sustained and high exposures to PM2.5, O3, polycyclic aromatic hydrocarbons, and metals. Young MCMA residents exhibit frontal tau hyperphosphorylation and amyloid-β (Aβ)1 - 42 diffuse plaques, and aggregated and hyperphosphorylated α-synuclein in olfactory nerves and key brainstem nuclei. We measured total prion protein (TPrP), total tau (T-tau), tau phosphorylated at threonine 181 (P-Tau), Aβ1-42, α-synuclein (t-α-syn and d-α-synuclein), BDNF, insulin, leptin, and/or inflammatory mediators, in 129 normal CSF samples from MCMA and clean air controls. Aβ1-42 and BDNF concentrations were significantly lower in MCMA children versus controls (p = 0.005 and 0.02, respectively). TPrP increased with cumulative PM2.5 up to 5 μg/m3 and then decreased, regardless of cumulative value or age (R2 = 0.56). TPrP strongly correlated with T-Tau and P-Tau, while d-α-synuclein showed a significant correlation with TNFα, IL10, and IL6 in MCMA children. Total synuclein showed an increment in childhood years related to cumulated PM2.5, followed by a decrease after age 12 years (R2 = 0.47), while d-α-synuclein exhibited a tendency to increase with cumulated PM2.5 (R2 = 0.30). CSF Aβ1-42, BDNF, α-synuclein, and TPrP changes are evolving in young MCMA urbanites historically showing underperformance in cognitive processes, odor identification deficits, downregulation of frontal cellular PrP, and neuropathological AD and PD hallmarks. Neuroprotection of young MCMA residents ought to be a public health priority.

Combustion-derived nanoparticles, the neuroenteric system, cervical vagus, hyperphosphorylated alpha synuclein and tau in young Mexico City residents

Mexico City (MC) young residents are exposed to high levels of fine particulate matter (PM_2.5), have high frontal concentrations of combustion-derived nanoparticles (CDNPs), accumulation of hyperphosphorylated aggregated α-synuclein (α-Syn) and early Parkinson's disease (PD). Swallowed CDNPs have easy access to epithelium and submucosa, damaging gastrointestinal (GI) barrier integrity and accessing the enteric nervous system (ENS). This study is focused on the ENS, vagus nerves and GI barrier in young MC v clean air controls. Electron microscopy of epithelial, endothelial and neural cells and immunoreactivity of stomach and vagus to phosphorylated ɑ-synuclein Ser129 and Hyperphosphorylated-Tau (Htau) were evaluated and CDNPs measured in ENS. CDNPs were abundant in erythrocytes, unmyelinated submucosal, perivascular and intramuscular nerve fibers, ganglionic neurons and vagus nerves and associated with organelle pathology. ɑSyn and Htau were present in 25/27 MC gastric,15/26 vagus and 18/27 gastric and 2/26 vagus samples respectively. We strongly suggest CDNPs are penetrating and damaging the GI barrier and reaching preganglionic parasympathetic fibers and the vagus nerve. This work highlights the potential role of CDNPs in the neuroenteric hyperphosphorylated ɑ-Syn and tau pathology as seen in Parkinson and Alzheimer's diseases. Highly oxidative, ubiquitous CDNPs constitute a biologically plausible path into Parkinson's and Alzheimer's pathogenesis.

Outdoor Ambient Air Pollution and Neurodegenerative Diseases: the Neuroinflammation Hypothesis

PURPOSE OF REVIEW

Accumulating research indicates that ambient outdoor air pollution impacts the brain and may affect neurodegenerative diseases, yet the potential underlying mechanisms are poorly understood.

RECENT FINDINGS

The neuroinflammation hypothesis holds that elevation of cytokines and reactive oxygen species in the brain mediates the deleterious effects of urban air pollution on the central nervous system (CNS). Studies in human and animal research document that neuroinflammation occurs in response to several inhaled pollutants. Microglia are a prominent source of cytokines and reactive oxygen species in the brain, implicated in the progressive neuron damage in diverse neurodegenerative diseases, and activated by inhaled components of urban air pollution through both direct and indirect pathways. The MAC1-NOX2 pathway has been identified as a mechanism through which microglia respond to different forms of air pollution, suggesting a potential common deleterious pathway. Multiple direct and indirect pathways in response to air pollution exposure likely interact in concert to exert CNS effects.

Exposures to fine particulate matter (PM2.5) and ozone above USA standards are associated with auditory brainstem dysmorphology and abnormal auditory brainstem evoked potentials in healthy young dogs

BACKGROUND

Delayed central conduction times in the auditory brainstem have been observed in Mexico City (MC) healthy children exposed to fine particulate matter (PM_2.5) and ozone (O₃) above the current United States Environmental Protection Agency (US-EPA) standards. MC children have α synuclein brainstem accumulation and medial superior olivary complex (MSO) dysmorphology. The present study used a dog model to investigate the potential effects of air pollution on the function and morphology of the auditory brainstem.

METHODOLOGY

Twenty-four dogs living in clean air v MC, average age 37.1 ± 26.3 months, underwent brainstem auditory evoked potential (BAEP) measurements. Eight dogs (4 MC, 4 Controls) were analysed for auditory brainstem morphology and histopathology.

RESULTS

MC dogs showed ventral cochlear nuclei hypotrophy and MSO dysmorphology with a significant decrease in cell body size, decreased neuronal packing density with regions in the nucleus devoid of neurons and marked gliosis. MC dogs showed significant delayed BAEP absolute wave I, III and V latencies compared to controls.

CONCLUSIONS

MC dogs show auditory nuclei dysmorphology and BAEPs consistent with an alteration of the generator sites of the auditory brainstem response waveform. This study puts forward the usefulness of BAEPs to study auditory brainstem neurodegenerative changes associated with air pollution in dogs. Recognition of the role of non-invasive BAEPs in urban dogs is warranted to elucidate novel neurodegenerative pathways link to air pollution and a promising early diagnostic strategy for Alzheimer's Disease.