Associations of particulate matter with dementia and mild cognitive impairment in China: A multicenter cross-sectional study

Summary: Ambient air pollution has been shown to be associated with the pathogenesis of dementia and mild cognitive impairment (MCI). However, few studies have examined these associations in well-characterized populations with low residential mobility, similar living habits, and a standardized assessment of both air pollution exposure and clinical outcome. This study examined the associations of long-term exposure to particulate matter (PM) air pollution with dementia and MCI, using data from the Chinese Veteran Clinical Research Platform. The cognitive function of elderly veterans from 277 communities in 18 Chinese cities was examined. Participants' daily exposures to aerodynamic diameters ≤2.5 μm (PM2.5) and ≤10 μm (PM10) during the 3 years prior to the survey were estimated using a satellite-based prediction. The adjusted odds ratios (ORs) and 95% confidence intervals of MCI associated with each 10 μg/m3 increase in PM2.5 and PM10 were 1.52 (1.39, 1.67) and 1.04 (1.00, 1.08), and those of dementia associated with PM2.5 and PM10 were 1.27 (1.11, 1.46) and 1.13 (1.05, 1.21), respectively. This demonstrates that long-term exposure to PM2.5 and PM10 can increase the prevalence of dementia/MCI among veterans in China. Higher ORs were observed for those with ≤9 years of educational attainment, those who actively attended physical activities, those who never smoked, former drinkers, and those who did not suffer from cerebral infarction. Improvement of ambient air quality, especially decreasing levels of PM2.5, may help to decrease the risk of dementia/MCI. Given the statistically significant association between PM and cognitive impairment demonstrated here, future studies should focus on examining the causal effect of PM pollution on dementia and MCI. Public summary: • Dementia and MCI are emerging as major public health problems, and PM2.5 is hypothesized to be associated with dementia and MCI • We examined the cognitive function of elderly veterans from 277 communities (a well-characterized population with low residential mobility, similar living habits, standardized assessment of both exposure and outcome), in 18 Chinese cities from December 2009 to December 2011 • Long-term exposure to PM, especially PM2.5 showed associations with dementia and MCI • The effect was more pronounced for people with no more than nine years of education • Besides, people with fewer other risk factors (lack of physical activities, smoking, drinking, cerebral infarction) are more susceptible to PM2.5 • Improvement of ambient air quality, especially PM2.5, might be helpful to decrease the risk of dementia and MC