Particulate matter exposure from motorized traffic and risk of conversion from mild cognitive impairment to dementia: An Italian prospective cohort study

• Published in: Environmental research Vol. 222; p. 115425
• Main Authors: Urbano, Teresa, Chiari, Annalisa, Malagoli, Carlotta, Cherubini, Andrea, Bedin, Roberta, Costanzini, Sofia, Teggi, Sergio, Maffeis, Giuseppe, Vinceti, Marco, Filippini, Tommaso
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.04.2023
• Subjects: aerodynamics; air; air pollutants; Air Pollutants - toxicity; Air pollution; Air Pollution - analysis; Alzheimer disease; Alzheimer Disease - chemically induced; Alzheimer's dementia; cerebrospinal fluid; chronic exposure; cognitive disorders; Cognitive Dysfunction - chemically induced; cohort studies; confidence interval; Dementia; Environmental Exposure - analysis; geographic information systems; hazard ratio; Humans; Mild cognitive impairment; Particulate matter; Particulate Matter - analysis; particulates; Prospective Studies; regression analysis; risk; traffic; Vehicular traffic; Air pollution; Vehicular traffic; Mild cognitive impairment; Alzheimer's dementia; Particulate matter; Dementia
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2023.115425

Based on epidemiologic and laboratory studies, exposure to air pollutants has been linked to many adverse health effects including a higher risk of dementia. In this study, we aimed to evaluate the effect of long-term exposure to outdoor air pollution on risk of conversion to dementia in a cohort of subjects with mild cognitive impairment (MCI). We recruited 53 Italian subjects newly-diagnosed with MCI. Within a geographical information system, we assessed recent outdoor air pollutant exposure, by modeling air levels of particulate matter with equivalent aerodynamic diameter ≤10 μm (PM10) from motorized traffic at participants’ residence. We investigated the relation of PM10 concentrations to subsequent conversion from MCI to any type of dementia. Using a Cox-proportional hazards model combined with a restricted cubic spline model, we computed the hazard ratio (HR) of dementia with its 95% confidence interval (CI) according to increasing PM10 exposure, adjusting for sex, age, and educational attainment. During a median follow up of 47.3 months, 34 participants developed dementia, in 26 cases diagnosed as Alzheimer's dementia. In non-linear restricted spline regression analysis, mean and maximum annual PM10 levels positively correlated with cerebrospinal fluid total and phosphorylated tau proteins concentrations, while they were inversely associated with β-amyloid. Concerning the risk of dementia, we found a positive association starting from above 10 μg/m3 for mean PM10 levels and above 35 μg/m3 for maximum PM10 levels. Specific estimates for Alzheimer's dementia were substantially similar. Adding other potential confounders to the multivariable model or removing early cases of dementia onset during the follow-up had little effect on the estimates. Our findings suggest that exposure to outdoor air pollutants, PM10 in particular, may non-linearly increase conversion from MCI to dementia above a certain ambient air concentration. •We longitudinally assessed conversion of mild cognitive impairment to dementia.•We estimated traffic-related particulate matter (PM10) exposure.•Mean and maximum PM10 levels were non-linearly associated with dementia risk.•PM10 levels were associated with alteration of neurodegeneration biomarkers.•High PM10 exposure may increase risk of overall dementia and Alzheimer's dementia.