Long-Term Exposure to Air Pollutants and Cognitive Function in Taiwanese Community-Dwelling Older Adults: A Four-Year Cohort Study

Abstract

Background: Previous studies have assessed limited cognitive domains with relatively short exposure to air pollutants, and studies in Asia are limited. Objective: This study aims to explore the association between long-term exposure to air pollutants and cognition in community-dwelling older adults. Methods: This four-year prospective cohort study recruited 605 older adults at baseline (2011–2013) and 360 participants remained at four-year follow-up. Global and domain-specific cognition were assessed biennially. Data on PM2.5 (particulate matter ≤ 2.5 μm diameter, 2005–2015), PM10 (1993–2015), and nitrogen dioxide (NO2, 1993–2015) were obtained from Taiwan Environmental Protection Administration (TEPA). Bayesian Maximum Entropy was utilized to estimate the spatiotemporal distribution of levels of these pollutants. Results: Exposure to high-level PM2.5 (>29.98 μg/m3) was associated with an increased risk of global cognitive impairment (adjusted odds ratio = 4.56; β = −0.60). High-level PMcoarse exposure (>26.50 μg/m3) was associated with poor verbal fluency (β = −0.19). High-level PM10 exposure (>51.20 μg/m3) was associated with poor executive function (β = −0.24). Medium-level NO2 exposure (>28.62 ppb) was associated with better verbal fluency (β = 0.12). Co-exposure to high concentrations of PM2.5, PMcoarse or PM10 and high concentration of NO2 were associated with poor verbal fluency (PM2.5 and NO2: β = −0.17; PMcoarse and NO2: β = −0.23; PM10 and NO2: β = −0.21) and poor executive function (PM10 and NO2: β = −0.16). These associations became more evident in women, apolipoprotein ε4 non-carriers, and those with education > 12 years. Conclusion: Long-term exposure to PM2.5 (higher than TEPA guidelines), PM10 (lower than TEPA guidelines) or co-exposure to PMx and NO2 were associated with poor global, verbal fluency, and executive function over 4 years.

Long-term exposure to particulate matter was associated with increased dementia risk using both traditional approaches and novel machine learning methods

“…A continued need to confront methodological challenges in this line of research has been noted 10 . In addition, evidence of long-term air pollution exposure and the risk of dementia in East Asia cities is limited 11 – 14 . As East Asia is one of the worst air pollution regions globally, more research is needed.…”

Long-term exposure to ambient air pollution and cognitive function in older US adults

“…8 Recent reviews of epidemiologic research on brain health has provided supportive evidences of chronic effects of exposure to PM 2.5 and traffic-related pollutants on cognitive impairment and dysfunction in older adults. 3,4,9,10 Ambient PM 2.5 represents a heterogeneous mixture of constituents from diverse sources such as fossil fuel combustion, biomass burning, and human activity where the contribution of a single component may vary differently by geographical locations. 11 However, little is known about which specific components of PM 2.5 may be implicated in the toxic effects on cognitive function.…”