OBJECTIVES: Although several environmental factors contribute to the etiology of late-life depressive symptoms, the role of ambient air pollution has been understudied. Experimental data support the neurotoxicity of airborne particulate matter with aerodynamic diameter of ≤2.5 μm (PM), but it remains unclear whether long-term exposure is associated with late-life depressive symptoms. Our secondary aim was to explore whether the observed associations between exposure and depressive symptoms are explained by dementia risk. 2.5
DESIGN, SETTING, AND PARTICIPANTS: Prospective community-dwelling cohort study from the Women's Health Initiative Study of Cognitive Aging (1999-2010). Our analyses included 1,989 older women (baseline age 73.3 ± 3.75) with no prior depression or cognitive impairment.
MEASUREMENTS: Participants completed annual assessments of depressive symptoms (15-item Geriatric Depression Scale). Average ambient PMexposure at the residential location was estimated by spatiotemporal modeling for the 3-years preceding each neuropsychological assessment. Participants underwent separate annual examinations for incident dementia defined by DSM-IV. Latent-class mixture models examined the association between PMand identified trajectories of symptoms. 2.5 2.5
RESULTS: Six trajectories of depressive symptoms were identified. Across all women, PMexposure was positively associated with depressive symptoms. The effect was especially strong in two clusters with sustained depressive symptoms (n = 625 sustained-mild [31%]; n = 125 sustained-moderate; [6%]). Among those with sustained-moderate symptoms, the estimated adverse effect of PMexposure was greater than that of hypertension. Among women without dementia, associations were modestly attenuated. 2.5 2.5
CONCLUSION: Long-term exposure to ambient fine particles was associated with increased depressive symptoms among older women without prior depression or cognitive impairment.
