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. 2020 Jul 1;77(7):801-809.
doi: 10.1001/jamaneurol.2019.4914.

Association Between Cardiovascular Disease and Long-term Exposure to Air Pollution With the Risk of Dementia

Giulia Grande  1 , Petter L S Ljungman  2   3 , Kristina Eneroth  4 , Tom Bellander  2 , Debora Rizzuto  1   5
Affiliations

Association Between Cardiovascular Disease and Long-term Exposure to Air Pollution With the Risk of Dementia

Giulia Grande et al. JAMA Neurol. .

Abstract

Importance: Emerging yet contrasting evidence associates air pollution with incident dementia, and the potential role of cardiovascular disease (CVD) in this association is unclear.

Objective: To investigate the association between long-term exposure to air pollution and dementia and to assess the role of CVD in that association.

Design, setting, and participants: Data for this cohort study were extracted from the ongoing Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), a longitudinal population-based study with baseline assessments from March 21, 2001, through August 30, 2004. Of the 5111 randomly selected residents in the Kungsholmen district of Stockholm 60 years or older and living at home or in institutions, 521 were not eligible (eg, due to death before the start of the study or no contact information). Among the remaining 4590 individuals, 3363 (73.3%) were assessed. For the current analysis, 2927 participants who did not have dementia at baseline were examined, with follow-up to 2013 (mean [SD] follow-up time, 6.01 [2.56] years). Follow-up was completed February 18, 2013, and data were analyzed from June 26, 2018, through June 20, 2019.

Exposures: Two major air pollutants (particulate matter ≤2.5 μm [PM2.5] and nitrogen oxide [NOx]) were assessed yearly from 1990, using dispersion models for outdoor levels at residential addresses.

Main outcomes and measures: The hazard of dementia was estimated using Cox proportional hazards regression models. The potential of CVD (ie, atrial fibrillation, ischemic heart disease, heart failure, and stroke) to modify and mediate the association between long-term exposure to air pollution and dementia was tested using stratified analyses and generalized structural equation modeling.

Results: At baseline, the mean (SD) age of the 2927 participants was 74.1 (10.7) years, and 1845 (63.0%) were female. Three hundred sixty-four participants with incident dementia were identified. The hazard of dementia increased by as much as 50% per interquartile range difference in mean pollutant levels during the previous 5 years at the residential address (hazard ratio [HR] for difference of 0.88 μg/m3 PM2.5, 1.54 [95% CI, 1.33-1.78]; HR for difference of 8.35 μg/m3 NOx, 1.14 [95% CI, 1.01-1.29]). Heart failure (HR for PM2.5, 1.93 [95% CI, 1.54-2.43]; HR for NOx, 1.43 [95% CI, 1.17-1.75]) and ischemic heart disease (HR for PM2.5, 1.67 [95% CI, 1.32-2.12]; HR for NOx, 1.36 [95% CI, 1.07-1.71]) enhanced the dementia risk, whereas stroke appeared to be the most important intermediate condition, explaining 49.4% of air pollution-related dementia cases.

Conclusions and relevance: This study found that long-term exposure to air pollution was associated with a higher risk of dementia. Heart failure and ischemic heart disease appeared to enhance the association between air pollution and dementia, whereas stroke seemed to be an important intermediate condition between the association of air pollution exposure with dementia.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Ljungman reported receiving personal fees from AFA Insurance and grants from Carl Bennett AB outside the submitted work. Dr Rizzuto reported receiving grants from the Swedish Research Council for Health, Working Life, and Welfare during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Trends in Modeled Concentrations of Residential Outdoor Pollution
Levels of particulate matter of no greater than 2.5 μm and nitrogen oxide were measured for 21 years (1990-2011) as annual mean levels for the entire cohort (n = 2927).
Figure 2.
Figure 2.. Hazard Ratios (HRs) of Dementia by Particulate Matter No Greater Than 2.5 μm (PM2.5) and Nitrogen Oxide Levels
Estimates are HRs derived from Cox proportional hazards regression models. Air pollutants are modeled using restricted cubic splines. Age is considered as time scale. Models are adjusted for sex, age at baseline, year of assessment, educational attainment, smoking status, socioeconomic status, early retirement, physical activity, depression, baseline Mini-Mental State Examination score, type 2 diabetes, body mass index, hypertension, and dyslipidemia. The exposure period ranges from 0 to 5 years before the event. The reference group is considered the mean exposure level in the entire population. Bars represent distribution of the exposure levels in the entire population and spikes represent the cases. Solid line indicates point estimates; dashed lines, 95% CIs.
Figure 3.
Figure 3.. Hazard Ratios (HR) of Dementia by Particulate Matter No Greater Than 2.5 μm (PM2.5) and Nitrogen Oxide Stratified by Cardiovascular Disease
Estimates are HRs derived from Cox proportional hazards regression models. Age is considered as time scale. Models are adjusted for sex, age at baseline, year of assessment, educational attainment, smoking status, socioeconomic status, early retirement, physical activity, body mass index, baseline Mini-Mental State Examination score, depression, hypertension, dyslipidemia, and type 2 diabetes. The time exposure period ranges from 0 to 5 years before the event. aP = .67 for interaction. bP = .001 for interaction. cP = .37 for interaction. dP = .50 for interaction. eP = .94 for interaction. fP = .02 for interaction. gP = .13 for interaction. hP = .10 for interaction.
Figure 4.
Figure 4.. Association Between Levels of Particulate Matter No Greater Than 2.5 μm (PM2.5) and Nitrogen Oxide and Dementia
Heart diseases and stroke were considered as mediators. Models are adjusted for sex, age at baseline, year of assessment, educational attainment, smoking status, socioeconomic status, early retirement, physical activity, baseline Mini-Mental State Examination score, body mass index, depression, hypertension, dyslipidemia, and type 2 diabetes. OR indicates odds ratio.
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References

    1. Winblad B, Amouyel P, Andrieu S, et al. Defeating Alzheimer’s disease and other dementias: a priority for European science and society. Lancet Neurol. 2016;15(5):455-532. doi: 10.1016/S1474-4422(16)00062-4 - DOI - PubMed
    1. Calderón-Garcidueñas L, Azzarelli B, Acuna H, et al. Air pollution and brain damage. Toxicol Pathol. 2002;30(3):373-389. doi: 10.1080/01926230252929954 - DOI - PubMed
    1. Block ML, Calderón-Garcidueñas L. Air pollution: mechanisms of neuroinflammation and CNS disease. Trends Neurosci. 2009;32(9):506-516. doi: 10.1016/j.tins.2009.05.009 - DOI - PMC - PubMed
    1. Power MC, Adar SD, Yanosky JD, Weuve J. Exposure to air pollution as a potential contributor to cognitive function, cognitive decline, brain imaging, and dementia: a systematic review of epidemiologic research. Neurotoxicology. 2016;56:235-253. doi: 10.1016/j.neuro.2016.06.004 - DOI - PMC - PubMed
    1. Cohen AJ, Brauer M, Burnett R, et al. Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. Lancet. 2017;389(10082):1907-1918. doi: 10.1016/S0140-6736(17)30505-6 - DOI - PMC - PubMed

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