Association of improved air quality with lower dementia risk in older women

Abstract

Late-life ambient air pollution is a risk factor for brain aging, but it remains unknown if improved air quality (AQ) lowers dementia risk. We studied a geographically diverse cohort of older women dementia free at baseline in 2008 to 2012 (n = 2,239, aged 74 to 92). Incident dementia was centrally adjudicated annually. Yearly mean concentrations of fine particulate matter (PM2.5) and nitrogen dioxide (NO2) were estimated using regionalized national universal kriging models and averaged over the 3-y period before baseline (recent exposure) and 10 y earlier (remote exposure). Reduction from remote to recent exposures was used as the indicator of improved AQ. Cox proportional hazard ratios (HRs) for dementia risk associated with AQ measures were estimated, adjusting for sociodemographic, lifestyle, and clinical characteristics. We identified 398 dementia cases during follow up (median = 6.1 y). PM2.5 and NO2 reduced significantly over the 10 y before baseline. Larger AQ improvement was associated with reduced dementia risks (HRPM2.5 0.80 per 1.78 μg/m3, 95% CI 0.71–0.91; HRNO2 0.80 per 3.91 parts per billion, 95% CI 0.71–0.90), equivalent to the lower risk observed in women 2.4 y younger at baseline. Higher PM2.5 at baseline was associated with higher dementia risk (HRPM2.5 1.16 per 2.90 μg/m3, 95% CI 0.98–1.38), but the lower dementia risk associated with improved AQ remained after further adjusting for recent exposure. The observed associations did not substantially differ by age, education, geographic region, Apolipoprotein E e4 genotypes, or cardiovascular risk factors. Long-term AQ improvement in late life was associated with lower dementia risk in older women.

Incident dementia and long-term exposure to constituents of fine particle air pollution: A national cohort study in the United States

“…(2021) ( 3 ) summarized the epidemiological evidence of the effects of air pollution on ADRD, and a positive association between long-term exposure to PM 2.5 mass and increased ADRD risks was consistently reported across almost all studies. Relevant publications on air pollution and ADRD have doubled since this review, with the majority of studies finding positive associations between PM 2.5 mass and either all-cause dementia or AD ( 4 – 6 ).…”

Hazed and Confused: The Effect of Air Pollution on Dementia

“…We follow prior medical studies and assess the role of later-in-life, long-term exposure to PM2.5 as measured by single-or multiple-year annual average ambient concentrations in explaining new diagnoses of dementia (Wang et al 2022, Li et al 2022, Mortimais et al 2021, Ran et al 2021, Shi et al 2021, Shi et al 2020, Grande 2020, Cacciottolo et al 2017). 3 Specifically, we observe the timing of individuals' initial diagnosis (or lack thereof) and how it relates to thirteen years (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) of annual average exposure to PM2.5 for them individually based on their precise residential locations each year, allowing us to measure individual-specific exposure histories.…”

Mitigating the impact of air pollution on dementia and brain health: Setting the policy agenda

“…The third actionable item is developing tools for assessing health behaviours, pre-existing conditions, or comorbid health conditions that prevent, slowdown, or exacerbate the impact of air pollution on brain healthalthough the ethical and legal implications of such public health screening strategies and data collection would need to be addressed, as in the case of genetic testing in early life. It would also include use of these tools to potentially slow the progression of cognitive disorders, cognitive decline and even dementia, post-diagnosis (e.g., Perera et al, 2021;Wang et al, 2022;Younan et al, 2022).…”

“…New research shows exposure to high levels of air pollutants at critical points in our lives, particularly in early life, is detrimental to brain health across the life course and increases the risk of dementia syndrome and related disorders (e.g., Delgado-Saborit et al, 2021;Guzmán et al, 2022;Ran et al, 2021;Wang et al, 2022;Younan et al, 2022). Examples include global cognition and neurodegenerative disorders, learning in childhood and stroke-related brain damage, and reduction in white matter and neuroinflammation (Chandra et al, 2022;Gartland et al, 2022;Guxens et al, 2018;Killin et al, 2016;Russ et al, 2021).…”