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Mohammadzadeh M, Khoshakhlagh AH, Grafman J. Air pollution: a latent key driving force of dementia. BMC Public Health 2024; 24:2370. [PMID: 39223534 PMCID: PMC11367863 DOI: 10.1186/s12889-024-19918-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Accepted: 08/28/2024] [Indexed: 09/04/2024] Open
Abstract
Many researchers have studied the role of air pollutants on cognitive function, changes in brain structure, and occurrence of dementia. Due to the wide range of studies and often contradictory results, the present systematic review was conducted to try and clarify the relationship between air pollutants and dementia. To identify studies for this review, a systematic search was conducted in Scopus, PubMed, and Web of Science databases (without historical restrictions) until May 22, 2023. The PECO statement was created to clarify the research question, and articles that did not meet the criteria of this statement were excluded. In this review, animal studies, laboratory studies, books, review articles, conference papers and letters to the editors were avoided. Also, studies focused on the effect of air pollutants on cellular and biochemical changes (without investigating dementia) were also excluded. A quality assessment was done according to the type of design of each article, using the checklist developed by the Joanna Briggs Institute (JBI). Finally, selected studies were reviewed and discussed in terms of Alzheimer's dementia and non-Alzheimer's dementia. We identified 14,924 articles through a systematic search in databases, and after comprehensive reviews, 53 articles were found to be eligible for inclusion in the current systematic review. The results showed that chronic exposure to higher levels of air pollutants was associated with adverse effects on cognitive abilities and the presence of dementia. Studies strongly supported the negative effects of PM2.5 and then NO2 on the brain and the development of neurodegenerative disorders in old age. Because the onset of brain structural changes due to dementia begins decades before the onset of disease symptoms, and that exposure to air pollution is considered a modifiable risk factor, taking preventive measures to reduce air pollution and introducing behavioral interventions to reduce people's exposure to pollutants is advisable.
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Affiliation(s)
- Mahdiyeh Mohammadzadeh
- Department of Health in Emergencies and Disasters, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Climate Change and Health Research Center (CCHRC), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran
| | - Amir Hossein Khoshakhlagh
- Department of Occupational Health Engineering, School of Health, Kashan University of Medical Sciences, Kashan, Iran.
| | - Jordan Grafman
- Department of Physical Medicine & Rehabilitation, Neurology, Cognitive Neurology and Alzheimer's Center, Department of Psychiatry, Feinberg School of Medicine & Department of Psychology, Weinberg College of Arts and Sciences, Northwestern University, Chicago, IL, USA
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Wilker EH, Osman M, Weisskopf MG. Ambient air pollution and clinical dementia: systematic review and meta-analysis. BMJ 2023; 381:e071620. [PMID: 37019461 PMCID: PMC10498344 DOI: 10.1136/bmj-2022-071620] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/28/2023] [Indexed: 04/07/2023]
Abstract
OBJECTIVE To investigate the role of air pollutants in risk of dementia, considering differences by study factors that could influence findings. DESIGN Systematic review and meta-analysis. DATA SOURCES EMBASE, PubMed, Web of Science, Psycinfo, and OVID Medline from database inception through July 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Studies 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. RESULTS 2080 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/m3 PM2.5 was 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/m3 nitrogen dioxide was 1.02 ((0.98 to 1.06); nine studies) and per 10 μg/m3 nitrogen oxide was 1.05 ((0.98 to 1.13); five studies). Ozone had no clear association with dementia (hazard ratio per 5 μg/m3 was 1.00 (0.98 to 1.05); four studies). CONCLUSION PM2.5 might 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 REGISTRATION PROSPERO CRD42021277083.
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Affiliation(s)
- Elissa H Wilker
- Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA
- Department of Environmental Heath, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Marwa Osman
- Department of Environmental Heath, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Marc G Weisskopf
- Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA
- Department of Environmental Heath, Harvard TH Chan School of Public Health, Boston, MA, USA
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Zhang HW, Tsai ZR, Kok VC, Peng HC, Chen YH, Tsai JJP, Hsu CY. Long-term ambient hydrocarbon exposure and incidence of urinary bladder cancer. Sci Rep 2022; 12:20799. [PMID: 36460770 PMCID: PMC9718740 DOI: 10.1038/s41598-022-25425-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 11/29/2022] [Indexed: 12/02/2022] Open
Abstract
Particulate matter and volatile organic compounds, including total hydrocarbons (THCs), are major ambient air pollutants. Primary nonmethane hydrocarbons (NMHCs) originate from vehicle emissions. The association between air pollution and urinary bladder cancer (UBC) is debatable. We investigated whether long-term exposure to ambient hydrocarbons increases UBC risk among people aged ≥ 20 years in Taiwan. Linkage dataset research with longitudinal design was conducted among 589,135 initially cancer-free individuals during 2000-2013; 12 airborne pollutants were identified. Several Cox models considering potential confounders were employed. The study outcomes were invasive or in situ UBC incidence over time. The targeted pollutant concentration was divided into three tertiles: T1/T2/T3. The mean age of individuals at risk was 42.5 (SD 15.7), and 50.5% of the individuals were men. The mean daily average over 10 years of airborne THC concentration was 2.25 ppm (SD 0.13), and NMHC was 0.29 ppm (SD 0.09). Both pollutants show long-term monotonic downward trend over time using the Mann-Kendall test. There was a dose-dependent increase in UBC at follow-up. UBC incidence per 100,000 enrollees according to T1/T2/T3 exposure to THC was 60.9, 221.2, and 651.8, respectively; it was 170.0/349.5/426.7 per 100,000 enrollees, corresponding to T1/T2/T3 exposure to NMHC, respectively. Without controlling for confounding air pollutants, the adjusted hazard ratio (adj.HR) was 1.83 (95% CI 1.75-1.91) per 0.13-ppm increase in THC; after controlling for PM2.5, adj.HR was even higher at 2.09 (95% CI 1.99-2.19). The adj.HR was 1.37 (95% CI 1.32-1.43) per 0.09-ppm increase in ambient NMHC concentration. After controlling for SO2 and CH4, the adj.HR was 1.10 (95% CI 1.06-1.15). Sensitivity analyses showed that UBC development risk was not sex-specific or influenced by diabetes status. Long-term exposure to THC and NMHC may be a risk factor for UBC development. Acknowledging pollutant sources can inform risk management strategies.
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Affiliation(s)
- Han-Wei Zhang
- Program for Aging, China Medical University, Taichung, Taiwan
- Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan
- Institute of Electrical Control Engineering, Department of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
- Biomedica Corporation, New Taipei, Taiwan
| | - Zhi-Ren Tsai
- Department of Computer Science and Information Engineering, Asia University, Taichung, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Center for Precision Medicine Research, Asia University, Taichung, Taiwan
| | - Victor C Kok
- Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan.
- Division of Medical Oncology, Kuang Tien General Hospital Cancer Center, 117 Shatien Rd Shalu Dist., Taichung, 43303, Taiwan.
| | | | - Yau-Hung Chen
- Department of Chemistry, Tamkang University, New Taipei City, 25137, Taiwan
| | - Jeffrey J P Tsai
- Center for Precision Medicine Research, Asia University, Taichung, Taiwan
- Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan
| | - Chung Y Hsu
- Graduate Institute of Biomedical Science, China Medical University, Taichung, Taiwan
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Tsai ZR, Zhang HW, Tseng CH, Peng HC, Kok VC, Li GP, Hsiung CA, Hsu CY. Late-onset epilepsy and subsequent increased risk of dementia. Aging (Albany NY) 2021; 13:3573-3587. [PMID: 33429365 PMCID: PMC7906153 DOI: 10.18632/aging.202299] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 11/11/2020] [Indexed: 02/07/2023]
Abstract
Inflammation is considered as a key pathogenesis factor of dementia and epilepsy. However, epilepsy's association with dementia, particularly its role in the development of dementia, remains unclear. To evaluate the association between epilepsy and the risk of dementia, in Taiwan, we have now conducted a retrospective cohort study comprising 675 individuals (age, ≥50 years) with epilepsy and 2,025 matched control subjects without epilepsy. In order to match individuals diagnosed with epilepsy with those with no diagnosis of epilepsy (comparison cohort), we utilized exact matching at a ratio of 1:3. Compared with those in the comparison cohort, individuals in the epilepsy cohort had a significantly increased risk of developing dementia (adjusted hazard ratio = 2.87, p < 0.001). A similar result has been observed after stratifying for sex (adjusted hazard ratio in males = 2.95, p < 0.001; adjusted hazard ratio in females = 2.66, p < 0.001). To conclude, based on these data, epileptic individuals ≥50 years were at a greater risk of developing dementia than people who do not have epilepsy, which indicates that a diagnosis of epilepsy presents a greater risk for the development of dementia.
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Affiliation(s)
- Zhi-Ren Tsai
- Department of Computer Science and Information Engineering, Asia University, Taichung, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Taichung City Smart Transportation Big Data Research Center, Taichung, Taiwan
- Pervasive Artificial Intelligence Research (PAIR) Labs, Hsinchu, Taiwan
- Biomdcare Corporation, New Taipei, Taiwan
| | - Han-Wei Zhang
- Biomdcare Corporation, New Taipei, Taiwan
- Program for Aging, China Medical University, Taichung, Taiwan
- Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan
- Institute of Electrical Control Engineering, Department of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu, Taiwan
| | - Chun-Hung Tseng
- Department of Neurology, China Medical University Hospital, and School of Medicine, China Medical University, Taichung, Taiwan
| | | | - Victor C. Kok
- Disease Informatics Research Group, Asia University, Taichung, Taiwan
- Department of Internal Medicine, Kuang Tien General Hospital, Taichung, Taiwan
| | - Gao Ping Li
- Zhongshan Hospital, Affiliated Hospital of Fudan University, Shanghai, China
| | - Chao A. Hsiung
- Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan
| | - Chun-Yi. Hsu
- Graduate Institute of Biomedical Science, China Medical University, Taichung, Taiwan
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