Air Pollution and Trajectories of Positive and Negative Affect in Older Women

Background/Aim Exposure to ambient air pollution, including PM2.5 (particulate matter <2.5 μm) and NO2 (nitrogen dioxide), is associated with depressive symptoms in older adulthood. Depression is characterized by low positive affect and high negative affect. Elucidating how exposure may differentially impact the emotional dimensions underlying depressive symptoms will deepen our understanding of the link between air pollution neurotoxicity and emotional health of older adults. Here we examined associations between air pollution and longitudinal trajectories of positive and negative affect in older women. Methods Women (N=2,114; baseline age=73.3±3.8 years), enrolled in the Women’s Health Initiative Study of Cognitive Aging (2000-2010), completed up to nine annual assessments with the Positive and Negative Affect Schedule (PANAS). Three-year average annual mean concentrations (scaled by interquartile range [IQR]) of ambient PM2.5 (in μg/m3; IQR=3.64 μg/m3) and NO2 (in ppb; IQR=10.35 ppb) before baseline were estimated at participants' addresses via spatiotemporal models. Latent-class mixture models were constructed to identify subgroups of women with similar trajectories of positive or negative affect over time. Multinomial logistic regressions were used to examine whether exposures predicted latent-class membership, adjusting for sociodemographic, lifestyle, and clinical characteristics. Results Two latent trajectories of positive affect (PA) were identified: (high-stable PA: 95% and decreasing PA: 5%). Higher exposure to NO2 (OR = 1.55, p=.008), but not PM2.5 (OR=1.23, p=.212), was significantly associated with increased odds of being classified as having decreasing PA relative to high-stable PA. Four latent trajectories of negative affect (NA; minimal-stable: 27%; mild-stable: 46%; moderate-stable:21%; and moderate-decreasing: 6%) were identified. Neither NO2 nor PM2.5 was predictive of latent class membership of NA trajectories. Conclusions Exposure to NO2 may contribute to reduction of PA in older adulthood. Future studies should examine brain structures and neural networks as well as behavioral mechanisms underlying PA changes associated with air pollution neurotoxicity in late life.