Are noise and air pollution related to the incidence of dementia? A cohort study in London, England
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Published version
Author(s)
Type
Journal Article
Abstract
OBJECTIVE: To investigate whether the incidence of dementia is related to residential levels of air and noise pollution in London. DESIGN: Retrospective cohort study using primary care data. SETTING: 75 Greater London practices. PARTICIPANTS: 130 978 adults aged 50-79 years registered with their general practices on 1 January 2005, with no recorded history of dementia or care home residence. PRIMARY AND SECONDARY OUTCOME MEASURES: A first recorded diagnosis of dementia and, where specified, subgroups of Alzheimer's disease and vascular dementia during 2005-2013. The average annual concentrations during 2004 of nitrogen dioxide (NO2), particulate matter with a median aerodynamic diameter </=2.5 microm (PM2.5) and ozone (O3) were estimated at 20x20 m resolution from dispersion models. Traffic intensity, distance from major road and night-time noise levels (Lnight) were estimated at the postcode level. All exposure measures were linked anonymously to clinical data via residential postcode. HRs from Cox models were adjusted for age, sex, ethnicity, smoking and body mass index, with further adjustments explored for area deprivation and comorbidity. RESULTS: 2181 subjects (1.7%) received an incident diagnosis of dementia (39% mentioning Alzheimer's disease, 29% vascular dementia). There was a positive exposure response relationship between dementia and all measures of air pollution except O3, which was not readily explained by further adjustment. Adults living in areas with the highest fifth of NO2 concentration (>41.5 microg/m(3)) versus the lowest fifth (<31.9 microg/m(3)) were at a higher risk of dementia (HR=1.40, 95% CI 1.12 to 1.74). Increases in dementia risk were also observed with PM2.5, PM2.5 specifically from primary traffic sources only and Lnight, but only NO2 and PM2.5 remained statistically significant in multipollutant models. Associations were more consistent for Alzheimer's disease than vascular dementia. CONCLUSIONS: We have found evidence of a positive association between residential levels of air pollution across London and being diagnosed with dementia, which is unexplained by known confounding factors.
Date Issued
2018-09-11
Date Acceptance
2018-01-01
Citation
BMJ Open, 2018, 8 (9)
ISSN
2044-6055
Publisher
BMJ Publishing Group
Journal / Book Title
BMJ Open
Volume
8
Issue
9
Copyright Statement
© 2018 Author(s) (or their employer(s)). Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
Sponsor
Medical Research Council (MRC)
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/30206085
Grant Number
MR/L01341X/1
Subjects
Aged *Air Pollution/adverse effects/prevention & control *Alzheimer Disease/diagnosis/epidemiology *Dementia, Vascular/diagnosis/epidemiology *Environmental Exposure/adverse effects/prevention & control Female Humans London/epidemiology Male Middle Aged Nitrogen Dioxide/analysis *Noise/adverse effects/prevention & control Particulate Matter/analysis Primary Health Care/statistics & numerical data Residence Characteristics/statistics & numerical data Risk Factors Vehicle Emissions/analysis *air pollution *alzheimer's disease *dementia *noise *primary care
Notes
Carey, Iain M Anderson, H Ross Atkinson, Richard W Beevers, Sean D Cook, Derek G Strachan, David P Dajnak, David Gulliver, John Kelly, Frank J eng MR/L01341X/1/Medical Research Council/United Kingdom NE/I007806/1/Department of Health/United Kingdom NE/I008039/1/Department of Health/United Kingdom NE/I00789X/1/Department of Health/United Kingdom Research Support, Non-U.S. Gov't England BMJ Open. 2018 Sep 11;8(9):e022404. doi: 10.1136/bmjopen-2018-022404. OBJECTIVE: To investigate whether the incidence of dementia is related to residential levels of air and noise pollution in London. DESIGN: Retrospective cohort study using primary care data. SETTING: 75 Greater London practices. PARTICIPANTS: 130 978 adults aged 50-79 years registered with their general practices on 1 January 2005, with no recorded history of dementia or care home residence. PRIMARY AND SECONDARY OUTCOME MEASURES: A first recorded diagnosis of dementia and, where specified, subgroups of Alzheimer's disease and vascular dementia during 2005-2013. The average annual concentrations during 2004 of nitrogen dioxide (NO2), particulate matter with a median aerodynamic diameter </=2.5 microm (PM2.5) and ozone (O3) were estimated at 20x20 m resolution from dispersion models. Traffic intensity, distance from major road and night-time noise levels (Lnight) were estimated at the postcode level. All exposure measures were linked anonymously to clinical data via residential postcode. HRs from Cox models were adjusted for age, sex, ethnicity, smoking and body mass index, with further adjustments explored for area deprivation and comorbidity. RESULTS: 2181 subjects (1.7%) received an incident diagnosis of dementia (39% mentioning Alzheimer's disease, 29% vascular dementia). There was a positive exposure response relationship between dementia and all measures of air pollution except O3, which was not readily explained by further adjustment. Adults living in areas with the highest fifth of NO2 concentration (>41.5 microg/m(3)) versus the lowest fifth (<31.9 microg/m(3)) were at a higher risk of dementia (HR=1.40, 95% CI 1.12 to 1.74). Increases in dementia risk were also observed with PM2.5, PM2.5 specifically from primary traffic sources only and Lnight, but only NO2 and PM2.5 remained statistically significant in multipollutant models. Associations were more consistent for Alzheimer's disease than vascular dementia. CONCLUSIONS: We have found evidence of a positive association between residential levels of air pollution across London and being diagnosed with dementia, which is unexplained by known confounding factors.
Publication Status
Published
Article Number
e022404
Date Publish Online
2018-09-12