Is air pollution associated with increased risk of cognitive decline? A systematic review

Cognitive function is an important component of aging and predicts quality of life, functional independence, and risk of institutionalization. Advances in our understanding of the role of cardiovascular risks have shown them to be closely associated with cognitive impairment and dementia. Because many cardiovascular risks are modifiable, it may be possible to maintain brain health and to prevent dementia in later life. The purpose of this American Heart Association (AHA)/American Stroke Association presidential advisory is to provide an initial definition of optimal brain health in adults and guidance on how to maintain brain health. We identify metrics to define optimal brain health in adults based on inclusion of factors that could be measured, monitored, and modified. From these practical considerations, we identified 7 metrics to define optimal brain health in adults that originated from AHA’s Life’s Simple 7: 4 ideal health behaviors (nonsmoking, physical activity at goal levels, healthy diet consistent with current guideline levels, and body mass index <25 kg/m2) and 3 ideal health factors (untreated blood pressure <120/<80 mm Hg, untreated total cholesterol <200 mg/dL, and fasting blood glucose <100 mg/dL). In addition, in relation to maintenance of cognitive health, we recommend following previously published guidance from the AHA/American Stroke Association, Institute of Medicine, and Alzheimer’s Association that incorporates control of cardiovascular risks and suggest social engagement and other related strategies. We define optimal brain health but recognize that the truly ideal circumstance may be uncommon because there is a continuum of brain health as demonstrated by AHA’s Life’s Simple 7. Therefore, there is opportunity to improve brain health through primordial prevention and other interventions. Furthermore, although cardiovascular risks align well with brain health, we acknowledge that other factors differing from those related to cardiovascular health may drive cognitive health. Defining optimal brain health in adults and its maintenance is consistent with the AHA’s Strategic Impact Goal to improve cardiovascular health of all Americans by 20% and to reduce deaths resulting from cardiovascular disease and stroke by 20% by the year 2020. This work in defining optimal brain health in adults serves to provide the AHA/American Stroke Association with a foundation for a new strategic direction going forward in cardiovascular health promotion and disease prevention.

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“…Thus, air pollution was not included as a metric for optimal brain health in this AHA statement. 120–122 …”

Section: Optimal Brain Healthmentioning

confidence: 99%

Defining Optimal Brain Health in Adults: A Presidential Advisory From the American Heart Association/American Stroke Association

Gorelick

Furie

Iadecola

et al. 2017

Stroke

302

271

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“…Fine particulate matter (PM 2.5 ) is an air pollutant consisting of small, inhalable particles with aerodynamic diameters less than 2.5 microns (μm) that are produced primarily from combustion and industrial sources. PM 2.5 is of particular interest for understanding air pollution effects on the aging brain because it is ubiquitous in the air we breath and, once inhaled, fine particles can pass into systemic circulation, leading to increased inflammation, and may ultimately translocate from the lungs into other organ systems such as the brain (Heusinkveld et al 2016; Peters et al 2015) where they can cause damage and pathophysiological changes consistent with cognitive decline and impairment. A link between PM 2.5 and cognitive function has been reported in several recent studies of older adults.…”

Section: Introductionmentioning

confidence: 99%

Neighborhood social stressors, fine particulate matter air pollution, and cognitive function among older U.S. adults

Ailshire

Karraker

Clarke

2017

Social Science & Medicine

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A growing number of studies have found a link between outdoor air pollution and cognitive function among older adults. Psychosocial stress is considered an important factor determining differential susceptibility to environmental hazards and older adults living in stressful neighborhoods may be particularly vulnerable to the adverse health effects of exposure to hazards such as air pollution. The objective of this study is to determine if neighborhood social stress amplifies the association between fine particulate matter air pollution (PM2.5) and poor cognitive function in older, community-dwelling adults. We use data on 779 U.S. adults ages 55 and older from the 2001/2002 wave of the Americans’ Changing Lives study. We determined annual average PM2.5 concentration in 2001 in the area of residence by linking respondents with EPA air monitoring data using census tract identifiers. Cognitive function was measured using the number of errors on the Short Portable Mental Status Questionnaire (SPMSQ). Exposure to neighborhood social stressors was measured using perceptions of disorder and decay and included subjective evaluations of neighborhood upkeep and the presence of deteriorating/abandoned buildings, trash, and empty lots. We used negative binomial regression to examine the interaction of neighborhood perceived stress and PM2.5 on the count of errors on the cognitive function assessment. We found that the association between PM2.5 and cognitive errors was stronger among older adults living in high stress neighborhoods. These findings support recent theoretical developments in environmental health and health disparities research emphasizing the synergistic effects of neighborhood social stressors and environmental hazards on residents’ health. Those living in socioeconomically disadvantaged neighborhoods, where social stressors and environmental hazards are more common, may be particularly susceptible to adverse health effects of social and physical environmental exposures.

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“…Air pollutants of interest are fine particulate matter with an aerodynamic diameter <2.5 µm (PM 2.5 ) and NO 2 because there is evidence that they may be risk factors Table 2 Correlates of brain and cognitive health and covariates, moderators and mediators of associations between environmental attributes and brain and cognitive health in the iMAP study by data collection component for cognitive ill health, and they are widely measured by governments for regulatory purposes, supporting the development of exposure models. [56][57][58] Pollution exposure can be categorised as general background ambient air pollution (air pollution from the range of sources including traffic, industry and natural, but not immediately influenced by nearby sources) and traffic-related air pollution in areas proximate to traffic (i.e., air pollution from cars, buses and trucks). Estimates of annual exposure to ambient air pollution for all participants at all assessment points will be computed.…”

Section: Exposures Outcomes and Covariates Exposuresmentioning

confidence: 99%

International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health

et al. 2020

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IntroductionNumerous studies have found associations between characteristics of urban environments and risk factors for dementia and cognitive decline, such as physical inactivity and obesity. However, the contribution of urban environments to brain and cognitive health has been seldom examined directly. This cohort study investigates the extent to which and how a wide range of characteristics of urban environments influence brain and cognitive health via lifestyle behaviours in mid-aged and older adults in three cities across three continents.Methods and analysisParticipants aged 50–79 years and living in preselected areas stratified by walkability, air pollution and socioeconomic status are being recruited in Melbourne (Australia), Barcelona (Spain) and Hong Kong (China) (n=1800 total; 600 per site). Two assessments taken 24 months apart will capture changes in brain and cognitive health. Cognitive function is gauged with a battery of eight standardised tests. Brain health is assessed using MRI scans in a subset of participants. Information on participants’ visited locations is collected via an interactive web-based mapping application and smartphone geolocation data. Environmental characteristics of visited locations, including the built and natural environments and their by-products (e.g., air pollution), are assessed using geographical information systems, online environmental audits and self-reports. Data on travel and lifestyle behaviours (e.g., physical and social activities) and participants’ characteristics (e.g., sociodemographics) are collected using objective and/or self-report measures.Ethics and disseminationThe study has been approved by the Human Research Ethics Committee of the Australian Catholic University, the Institutional Review Board of the University of Hong Kong and the Parc de Salut Mar Clinical Research Ethics Committee of the Government of Catalonia. Results will be communicated through standard scientific channels. Methods will be made freely available via a study-dedicated website.Trial registration numberACTRN12619000817145.

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Is air pollution associated with increased risk of cognitive decline? A systematic review

Abstract: this systematic review highlights that there is some evidence of a potential association between air pollution and subsequent cognitive decline. Further work is clearly required and longitudinal analysis of ongoing cohort studies or new research would add much needed clarity to this area.

Cited by 53 publications

References 29 publications

Defining Optimal Brain Health in Adults: A Presidential Advisory From the American Heart Association/American Stroke Association

Defining Optimal Brain Health in Adults: A Presidential Advisory From the American Heart Association/American Stroke Association

Neighborhood social stressors, fine particulate matter air pollution, and cognitive function among older U.S. adults

International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health

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