Life course exposure to air pollution and the risk of mild cognitive impairment and dementia in the Lothian Birth Cohort 1936

Abstract

AbstractBackgroundAir pollution has been associated with the risk of pathological cognitive decline and dementia (Chandra et al., 2022). Past research has focused on cross‐sectional associations or short‐term exposure measurement, and there is a lack of studies investigating the impact of air pollution throughout the life course of the individual which examines sensitive periods. In this study, the relationship of air pollution exposure at different periods across the life course and the risk of dementia and mild cognitive impairment (MCI) was investigated.MethodHistoric fine particulate matter (PM2.5) was modeled using the EMEP4UK atmospheric chemistry transport model for several time periods (1935, 1950, 1970, 1980, and 1990) was combined with contemporary data for time period 2001 and 2007 to calculate the lifetime exposure for 576 participants of the Lothian Birth Cohort (LBC) 1936 who had information about lifetime residential history.There were 69 individuals with all‐cause dementia from age 70 years (baseline) onwards were clinically ascertained and 156 individuals with MCI derived at the ages 76, 79, and 82 years according to the NIA‐AA workgroups guidelines. A multivariable Cox proportional hazards model was developed to investigate associations between PM2.5 exposure at each time period with both cognitive outcomes, adjusting for sex, parental occupational social class (OSC) and of Apolipoprotein e4 allele (APOE4) status, childhood smoking (<16 years), years of education, adulthood OSC, smoking status at age 70, and early retirement (<60 years) dependent on time period.ResultHigher exposure (1SD [0.25µg/m3]) of PM2.5 in later life (2007, age 71 years) had a statistically significant (P = 0.0262) association with increased risk of MCI (HR 1.25, 95% CI 1.02‐1.54) and other time periods were positively associated but not statistically significant (P>0.05). There was no statistically significant (P>0.05) association between PM2.5 exposure at any time period and risk of all cause dementia.ConclusionLater life exposure to PM2.5 had a positive association with MCI which could suggest that this is a sensitive period in the life course model. This could indicate that people in later life are more susceptible to the impact of air pollution on cognitive decline and therefore risk of MCI.