Ambient Air Pollution Exposures and Risk of Parkinson Disease

Abstract

Background:Few epidemiologic studies have evaluated the effects of air pollution on the risk of Parkinson disease (PD).Objective:We investigated the associations of long-term residential concentrations of ambient particulate matter (PM) < 10 μm in diameter (PM10) and < 2.5 μm in diameter (PM2.5) and nitrogen dioxide (NO2) in relation to PD risk.Methods:Our nested case–control analysis included 1,556 self-reported physician-diagnosed PD cases identified between 1995 and 2006 and 3,313 controls frequency-matched on age, sex, and race. We geocoded home addresses reported in 1995–1996 and estimated the average ambient concentrations of PM10, PM2.5, and NO2 using a national fine-scale geostatistical model incorporating roadway information and other geographic covariates. Air pollutant exposures were analyzed as both quintiles and continuous variables, adjusting for matching variables and potential confounders.Results:We observed no statistically significant overall association between PM or NO2 exposures and PD risk. However, in preplanned subgroup analyses, a higher risk of PD was associated with higher exposure to PM10 (ORQ5 vs. Q1 = 1.65; 95% CI: 1.11, 2.45; p-trend = 0.02) among women, and with higher exposure to PM2.5 (ORQ5 vs. Q1 = 1.29; 95% CI: 0.94, 1.76; p-trend = 0.04) among never smokers. In post hoc analyses among female never smokers, both PM2.5 (ORQ5 vs. Q1 = 1.79; 95% CI: 1.01, 3.17; p-trend = 0.05) and PM10 (ORQ5 vs. Q1 = 2.34; 95% CI: 1.29, 4.26; p-trend = 0.01) showed positive associations with PD risk. Analyses based on continuous exposure variables generally showed similar but nonsignificant associations.Conclusions:Overall, we found limited evidence for an association between exposures to ambient PM10, PM2.5, or NO2 and PD risk. The suggestive evidence that exposures to PM2.5 and PM10 may increase PD risk among female never smokers warrants further investigation.Citation:Liu R, Young MT, Chen JC, Kaufman JD, Chen H. 2016. Ambient air pollution exposures and risk of Parkinson disease. Environ Health Perspect 124:1759–1765; http://dx.doi.org/10.1289/EHP135

Air pollution and Parkinson’s disease – evidence and future directions

“…When stratified by smoking status, significant associations were observed among former and current smokers, but not among never-smokers. This observation was somewhat contrary to the finding by Liu et al (34), who observed an effect of PM among never-smokers and female never-smokers. However, Liu et al (34) also noted no significant effect of NO 2 among the rural and urban subgroups.…”

“…Thus, studies sufficiently powered to examine the effects of air pollution on PD risk and progression in specific subgroups, such as nonsmokers, gender-specific groups, and other subgroups relevant to PD are needed. The PAGE study by Liu et al (34) (Table 1), reported significant positive associations between PM 10 and PM 2.5 and the risk of PD in female never-smokers, highlighting the importance of stratified and interaction analyses. Few of the studies included in this review stratified their analyses by gender or smoking [e.g.…”

“…In a nested case-control study within the National Institutes of Health (NIH) -AARP Diet and Health Study (34), Liu et al (34) examined exposure to PM 10 , PM 2.5 and NO 2 with relation to the odds of PD among 1556 self-reported PD cases and 3313 matched controls. Air pollution exposure was estimated by using a nationwide fine-scale geostatistical model that incorporated roadway information and other geographic covariates.…”

The effects of air pollution on individual psychological distress

“…These models showed high cross-validated R 2 , with a national R 2 of 0.88, and well-calibrated predictive intervals. This approach has also been applied in several recent epidemiologic studies of air pollution and health 40,41,42,43,44 . In this work, for each interview year, predictions were made at the census block centroid of respondents’ census blocks of residence, the smallest unit of geography available in the PSID.…”

Advances in Understanding Air Pollution and CVD

“…54 Although there was not strong evidence for an association between exposures to ambient PM 10 , PM 2.5 , or NO 2 concentrations and risk of Parkinson's disease in older adults, subgroup analyses suggested that female nonsmokers exposed to higher concentrations of PM 10 or PM 2.5 may have a higher risk for Parkinson's disease. 55 …”