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Ambient fine particulate matter alters cerebral hemodynamics in the elderly.

ABSTRACT: Short-term elevations in fine particulate matter air pollution (PM2.5) are associated with increased risk of acute cerebrovascular events. Evidence from the peripheral circulation suggests that vascular dysfunction may be a central mechanism. However, the effects of PM2.5 on cerebrovascular function and hemodynamics are unknown.We used transcranial Doppler ultrasound to measure beat-to-beat blood flow velocity in the middle cerebral artery at rest and in response to changes in end-tidal CO2 (cerebral vasoreactivity) and arterial blood pressure (cerebral autoregulation) in 482 participants from the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly (MOBILIZE) of Boston study. We used linear mixed effects models with random subject intercepts to evaluate the association between cerebrovascular hemodynamic parameters and mean PM2.5 levels 1 to 28 days earlier adjusting for age, race, medical history, meteorologic covariates, day of week, temporal trends, and season.An interquartile range increase (3.0 µg/m(3)) in mean PM2.5 levels during the previous 28 days was associated with an 8.6% (95% confidence interval, 3.7%-13.8%; P<0.001) higher cerebral vascular resistance and a 7.5% (95% confidence interval, 4.2%-10.6%; P<0.001) lower blood flow velocity at rest. Measures of cerebral vasoreactivity and autoregulation were not associated with PM2.5 levels.In this cohort of community-dwelling seniors, exposure to PM2.5 was associated with higher resting cerebrovascular resistance and lower cerebral blood flow velocity. If replicated, these findings suggest that alterations in cerebrovascular hemodynamics may underlie the increased risk of particle-related acute cerebrovascular events.

SUBMITTER: Wellenius GA

PROVIDER: S-EPMC3722046 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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Ambient fine particulate matter alters cerebral hemodynamics in the elderly.

Wellenius Gregory A GA Boyle Luke D LD Wilker Elissa H EH Sorond Farzaneh A FA Coull Brent A BA Koutrakis Petros P Mittleman Murray A MA Lipsitz Lewis A LA

Stroke 20130601 6

<h4>Background and purpose</h4>Short-term elevations in fine particulate matter air pollution (PM2.5) are associated with increased risk of acute cerebrovascular events. Evidence from the peripheral circulation suggests that vascular dysfunction may be a central mechanism. However, the effects of PM2.5 on cerebrovascular function and hemodynamics are unknown.<h4>Methods</h4>We used transcranial Doppler ultrasound to measure beat-to-beat blood flow velocity in the middle cerebral artery at rest a ...[more]

PMID: 23709640

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Project description:Background/objectivePoor air quality is implicated as a risk factor for cognitive impairment and dementia. Few studies have examined these associations longitudinally in well-characterized population-based cohorts with standardized annual assessment of both mild cognitive impairment (MCI) and dementia. We investigated the association between estimated ambient fine particulate matter (PM2.5 ) and risk of incident MCI and dementia in a post-industrial region known for historically poor air quality.Setting/participantsAdults aged 65+ years in a population-based cohort (n = 1572).MeasurementsCensus tract level PM2.5 from Environmental Protection Agency (EPA) air quality monitors; Clinical Dementia Rating (CDR)®.DesignWe estimated ambient PM2.5 exposure (μg/m3 , single-year and 5-year averages) by geocoding participants' residential addresses to census tracts with daily EPA PM2.5 measurements from 2002 to 2014. Using Bayesian spatial regression modeling adjusted for age, sex, education, smoking history, and household income, we examined the association between estimated PM2.5 exposure and risk of incident MCI (CDR = 0.5) and incident dementia (CDR ≥ 1.0).ResultsModeling estimated single-year exposure, each 1 μg/m3 higher ambient PM2.5 was associated with 67% higher adjusted risk of incident dementia (hazard ratio [HR] = 1.669, 95% credible interval [CI]: 1.298, 2.136) and 75% higher adjusted risk of incident MCI (HR = 1.746, 95% CI: 1.518, 2.032). Estimates were higher when modeling 5-year ambient PM2.5 exposure for incident dementia (HR = 2.082, 95% CI: 1.528, 3.015) and incident MCI (HR = 3.419, 95% CI: 2.806, 4.164).ConclusionsHigher estimated ambient PM2.5 was associated with higher risk of incident MCI and dementia, particularly when considering longer-term exposure, and independent of demographic characteristics and smoking history. Targeting poor air quality may be a reasonable population-wide intervention to reduce the risk of cognitive impairment in older adults, particularly in regions exceeding current recommendations for safe exposure to PM2.5 .

Project description:ImportanceOutdoor particulate matter 2.5 μm or less in diameter (PM2.5) is a ubiquitous environmental neurotoxicant that may affect the developing brain. Little is known about associations between PM2.5 and white matter connectivity.ObjectivesTo assess associations between annual residential PM2.5 exposure and white matter microstructure health in a US sample of children 9 to 10 years of age and to examine whether associations are specific to certain white matter pathways or vary across neuroimaging diffusion markers reflective of intracellular and extracellular microstructural processes.Design, setting, and participantsThis cross-sectional study, the Adolescent Brain and Cognitive Development (ABCD) Study, was composed of 21 study sites across the US and used baseline data collected from children 9 to 10 years of age from September 1, 2016, to October 15, 2018. Data analysis was performed from September 15, 2020, to June 30, 2021.ExposuresAnnual mean PM2.5 exposure estimated by ensemble-based models and assigned to the primary residential addresses at baseline.Main outcomes and measuresDiffusion-weighted imaging (DWI) and tractography were used to delineate white matter tracts. The biophysical modeling technique of restriction spectrum imaging (RSI) was implemented to examine total hindered diffusion and restricted isotropic and anisotropic intracellular diffusion in each tract. Hierarchical mixed-effects models with natural splines were used to analyze the associations between PM2.5 exposure and DWI.ResultsIn a study population of 7602 children (mean [SD] age, 119.1 [7.42] months; 3955 [52.0%] female; 160 [ 21.%] Asian, 1025 [13.5%] Black, 1616 [21.3%] Hispanic, 4025 [52.9%] White, and 774 [10.2%] other [identified by parents as American Indian/Native American or Alaska Native; Native Hawaiian, Guamanian, Samoan, other Pacific Islander; Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese, or other Asian; or other race]), associations were seen between annual ambient PM2.5 and hemispheric differences in white matter microstructure. Hemisphere-stratified models revealed significant associations between PM2.5 exposure and restricted isotropic intracellular diffusion in the left cingulum, in the left superior longitudinal fasciculus, and bilaterally in the fornix and uncinate fasciculus. In tracts with strong positive associations, a PM2.5 increase from 8 to 12 μg/m3 was associated with increases of 2.16% (95% CI, 0.49%-3.84%) in the left cingulum, 1.95% (95% CI, 0.43%-3.47%) in the left uncinate, and 1.68% (95% CI, 0.01%-3.34%) in the right uncinate. Widespread negative associations were observed between PM2.5 and mean diffusivity.Conclusions and relevanceThe findings of this cross-sectional study suggest that annual mean PM2.5 exposure during childhood is associated with increased restricted isotropic diffusion and decreased mean diffusivity of specific white matter tracts, potentially reflecting differences in the composition of white matter microarchitecture.

Project description:BackgroundFetal growth restriction (FGR) is not only a major determinant of perinatal morbidity and mortality but also leads to adverse health effects in later life. Over the past decade, numerous studies have indicated that maternal exposure to ambient air pollution has been a risk factor for abnormal fetal growth in developed countries where PM2.5 levels are relatively low. However, studies in highly polluted regions, such as China, and studies that rely on assessments in utero are scarce.MethodsA total of 7965 women were selected from 11,441 women from the Shanghai Maternity and Infant Living Environment (SMILE) cohort who were pregnant between January 1, 2014, and April 30, 2015. From January 1, 2014, to April 30, 2015, weekly average PM2.5 values from 53 monitors were calculated and the inverse distance weighted (IDW) method was used to create a Shanghai pollution surface map according to the participants residential addresses. Individual exposure was the average PM2.5 value of every gestational week between the first gestational week and one week before the ultrasound measurement date (the range of measurements per participant was 1 to 10). Repeated fetal ultrasound measurements during gestational weeks 14~40 were selected. The estimated fetal weight (EFW) was calculated by biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL) formulas. In total, 29,926 ultrasound measurements were analysed. Demographic variables, other pollutants (SO2, NO2, PM10 and O3) and relative humidity and temperature were controlled for potential confounding through generalized estimating equations (GEE).ResultsThe full model showed that with each 10 μg/m3 increase in PM2.5 exposure, the means (mm) of AC, BPD, FL decreased by 5.48 (- 9.06, - 1.91), 5.57 (- 6.66, - 4.47), and 5.47 (- 6.39, - 4.55), respectively; the mean EFW decreased by 14.49 (- 16.05, - 13.49) grams by Hadlock's third formula and 13.56 (- 14.71, - 12.50) grams by Shepard's formula with each 10 μg/m3 increase in PM2.5 exposure.ConclusionsA negative correlation existed between maternal PM2.5 exposure during pregnancy and fetal growth indicators, which may increase the risk of fetal growth restriction.

Project description:Murine Pulmonary Responses to Ambient Baltimore Particulate Matter: Genomic Analysis and Contribution to Airway Hyperresponsiveness Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and chronic airway inflammation. Environmental factors such as ambient particulate matter (PM), a major air pollutant, has been demonstrated in epidemiological studies to contribute to asthma exacerbation and increased asthma prevalence. OBJECTIVE: We investigated the genomic and pathophysiological effects of Baltimore PM (median diameter 1.78 µm) in a murine model of asthma to identify potential biomarkers. METHODS: A/J mice with ovalbumin (OVA) –induced AHR were exposed to PM (20 mg/kg, intratracheal), and both AHR and bronchoalveolar lavage (BAL) were assayed on days 1, 4, and 7 post exposure. Lung gene expression profiling (Affymetrix Mouse430_ 2.0) by PM (20 mg/kg, intratracheal) were assayed on OVA- and / or PM--challenged mice. RESULTS: Significant increases of airway responsiveness in OVA-treated mice were observed, indicating an asthmatic phenotype. Ambient PM exposure induced significant changes in AHR in both naive mice and OVA-induced asthmatic mice. In both naive and OVA challenged asthmatic mice, PM induced eosinophil and neutrophil infiltration into airways, elevated BAL protein content, and stimulated secretion of TH1 cytokines (IFN-g, IL-6, and TNF-a) and TH2 cytokines (IL-4, IL-5, and eotaxin) into BAL. Consistent with these results, PM induced expression of genes of innate immune response, chemotaxis and complementary system. CONCLUSION: These studies, consistent with epidemiological data, indicate that PM increases AHR and lung inflammation in naïve mice and exacerbates the asthma phenotype of increased AHR and gene expression pattern changes correlated with acute lung inflammation and airway damage. We used microarrays to detail the global programme of gene expression induced by rhPBEF treatment and VALI. Keywords: gene expression

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Ambient fine particulate matter alters cerebral hemodynamics in the elderly.

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Ambient fine particulate matter alters cerebral hemodynamics in the elderly.

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