Air quality improvement and incident dementia: Effects of observed and hypothetical reductions in air pollutant using parametric g‐computation

Letellier, Noémie; Gutierrez, Laure‐Anne; Duchesne, Jeanne; Chen, Chen; Ilango, Sindana D.; Helmer, Catherine; Berr, Claudine; Mortamais, Marion; Benmarhnia, Tarik

doi:10.1002/alz.12606

Cited by 8 publications

(5 citation statements)

References 56 publications

(125 reference statements)

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“…Our initial review identified 2079 publications (1092 unique) across the different databases, and one additional article found from the reference lists of other papers ( fig 1 ). A total of 51 publications met the inclusion criteria, 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 key characteristics of which are in the supplementary material 2 and 3. Particulate matter <2.5 µm in diameter (PM 2.5 ) was considered most frequently (n=38).…”

Section: Resultsmentioning

confidence: 99%

“…Among the 51 studies, we only used 16 in the meta-analyses for several reasons ( fig 1 ). When we excluded a study because the data source was the same as another paper, 18 19 27 28 44 49 57 58 63 65 we included the study that we considered primary (based on larger numbers or least risk of bias, etc). Active case ascertainment studies all used some form of screening of the entire study population followed by in-person evaluation for dementia among individuals who did not have dementia at baseline.…”

Section: Resultsmentioning

confidence: 99%

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Ambient air pollution and clinical dementia: systematic review and meta-analysis

Wilker

Osman

Weisskopf

2023

BMJ

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ObjectiveTo investigate the role of air pollutants in risk of dementia, considering differences by study factors that could influence findings.DesignSystematic review and meta-analysis.Data sourcesEMBASE, PubMed, Web of Science, Psycinfo, and OVID Medline from database inception through July 2022.Eligibility criteria for selecting studiesStudies that included adults (≥18 years), a longitudinal follow-up, considered US Environmental Protection Agency criteria air pollutants and proxies of traffic pollution, averaged exposure over a year or more, and reported associations between ambient pollutants and clinical dementia. Two authors independently extracted data using a predefined data extraction form and assessed risk of bias using the Risk of Bias In Non-randomised Studies of Exposures (ROBINS-E) tool. A meta-analysis with Knapp-Hartung standard errors was done when at least three studies for a given pollutant used comparable approaches.Results2080 records identified 51 studies for inclusion. Most studies were at high risk of bias, although in many cases bias was towards the null. 14 studies could be meta-analysed for particulate matter <2.5 µm in diameter (PM2.5). The overall hazard ratio per 2 μg/m3PM2.5was 1.04 (95% confidence interval 0.99 to 1.09). The hazard ratio among seven studies that used active case ascertainment was 1.42 (1.00 to 2.02) and among seven studies that used passive case ascertainment was 1.03 (0.98 to 1.07). The overall hazard ratio per 10 μg/m3nitrogen dioxide was 1.02 ((0.98 to 1.06); nine studies) and per 10 μg/m3nitrogen oxide was 1.05 ((0.98 to 1.13); five studies). Ozone had no clear association with dementia (hazard ratio per 5 μg/m3was 1.00 (0.98 to 1.05); four studies).ConclusionPM2.5might be a risk factor for dementia, as well as nitrogen dioxide and nitrogen oxide, although with more limited data. The meta-analysed hazard ratios are subject to limitations that require interpretation with caution. Outcome ascertainment approaches differ across studies and each exposure assessment approach likely is only a proxy for causally relevant exposure in relation to clinical dementia outcomes. Studies that evaluate critical periods of exposure and pollutants other than PM2.5, and studies that actively assess all participants for outcomes are needed. Nonetheless, our results can provide current best estimates for use in burden of disease and regulatory setting efforts.Systematic review registrationPROSPERO CRD42021277083.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Ambient air pollution and clinical dementia: systematic review and meta-analysis

Wilker

Osman

Weisskopf

2023

BMJ

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“…Identifying vulnerable subgroups who might particularly benefit of air quality improvements continues to be important to safeguard public health and in setting efficient and appropriate air quality standards. 34 In this study, we found that higher concentrations of tHcy increased the detrimental effect of air pollution by 50%, whereas raised methionine reduced the air pollutant-related dementia risk by 30%. We also found that a higher Met:tHcy ratio was associated with a reduced dementia risk related to air pollution exposure.…”

Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Association of Long-term Exposure to Air Pollution and Dementia Risk

et al. 2023

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Background and objectives:Growing evidence links air pollution with dementia risk, but the biological mechanisms are largely unknown. We investigated the role played by homocysteine (tHcy) and methionine in this association and explored whether this could be explained by cardiovascular diseases (CVDs).Methods:Data were extracted from the ongoing Swedish National study on Aging and Care in Kungsholmen (SNAC-K), a longitudinal population-based study. At baseline, 2512 dementia-free participants were examined up to 2013 (mean follow-up: 5.18±2.96 years). Two air pollutants (particulate matter ≤2.5μm [PM2.5] and nitrogen oxides [NOX]) were assessed yearly from 1990 until 2013 using dispersion models at residential addresses. The hazard ratio of dementia over air pollution levels was estimated using Cox models adjusted for age, sex, education, smoking, socioeconomic status, physical activity, retirement age, creatinine, year of assessment and use of supplements. The total effect of air pollutants on dementia was decomposed into four pathways involving tHcy/methionine: 1. Direct effect; 2. Indirect effect (mediation); 3. Effect due to interaction; and 4. Effect due to both mediation and interaction. To test whether the association was independent from CVDs (ischemic heart disease, atrial fibrillation, heart failure and stroke), we repeated the analyses excluding those individuals who developed CVDs.Results:Mean age of the study participants was 73.4 (SD:10.4) and 62.1% were females. During an average period of five years (mean:5.18; SD:2.96 years), 376 incident dementia cases were identified. There was a 70% increased hazard of dementia per unit increase of PM2.5during the 5-years before baseline (HR:1.71;95%CI:1.33-2.09). Overall, 50% (51.6%;95%CI:9.0;94.1) of the total effect of PM2.5on dementia was due to mediation of tHcy (6.6%;95%CI:1.6;11.6) and/or interaction (47.8%;95%CI:4.9;91.7) with tHcy and 48.4% (p=0.03) to the direct effect of PM2.5on dementia. High levels of methionine reduced the dementia hazard linked to PM2.5by 31% (HR:0.69;95%CI:0.56;0.85) with 24.8% attributable to the interaction with methionine and 25.9% (p=0.001) to the direct effect of PM2.5. No mediation effect was found through methionine. Attenuated results were obtained for NOx. Findings for tHcy were attenuated after excluding those who developed CVDs, while remained similar for methionine.Discussion:High levels of homocysteine enhanced the dementia risk attributed to air pollution, while high methionine concentrations reduced this risk. The impact of homocysteine on cardiovascular conditions partly explains this association. Alternative pathways other than cardiovascular mechanisms may be at play between methionine and dementia.

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“…Evidence that a reduction in air pollution is associated with a lower incidence of dementia is only just emerging 1011. Most studies so far have been conducted in Europe and North America.…”

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confidence: 99%

Air pollution and dementia

Sommerlad

Liu

2023

BMJ

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Due to the ageing global population, the number of people with dementia worldwide is predicted to rise from over 50 million in 2020 to more than 150 million by 2050, 1 with associated higher economic, social, and individual costs. 2 As such, identification of factors that can be targeted to reduce dementia's impact is urgently needed. The plausible effect of ambient air pollutants on brain pathology, via cerebrovascular disease or inflammation, 3 has contributed to an increasing volume of research exploring whether air pollution is a risk factor for dementia. In a linked BMJ paper, 4 Wilker and colleagues (

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Air quality improvement and incident dementia: Effects of observed and hypothetical reductions in air pollutant using parametric g‐computation

Cited by 8 publications

References 56 publications

Ambient air pollution and clinical dementia: systematic review and meta-analysis

Ambient air pollution and clinical dementia: systematic review and meta-analysis

Association of Long-term Exposure to Air Pollution and Dementia Risk

Air pollution and dementia

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