Heat, Fine Particulates, and Diagnosis of Dementia: A matched Case Control Study in North Carolina from 2003 to 2016

Background and Aim: Dementia continues to pose a serious health concern for aging populations around the world and may be affected by fine particulate (PM2.5) air pollution. As our planet warms and climates shift, environmental factors may contribute to chronic health outcomes, including dementia. We aim to determine if any association between prior year average temperature and diagnosis of dementia is discernable using available medical records data.  Methods: Using a random sample of University of North Carolina (UNC) electronic health records , we identified 318 individuals with any diagnosis of dementia. We utilized a 4:1 matched case-control design to link each case with hospital-based controls by birth year, sex, race, Census 2010 income and education tertiles, and climate zone. Climate data was derived from PRISM Climate Group data. Prior year average air temperature (min=12.26°C max=18.50°C), relative humidity (min=58.18% max=75.74%), and apparent temperature (min=11.86°C max=19.86°C) were calculated based on patient zip code. We also examined associations with prior year PM2.5 (min=5.50 µg/m3 max=15.56 µg/m3) estimated using an ensemble machine learning model and first diagnosis of dementia or first non-dementia diagnosis for controls. We conducted multivariable logistic regression models to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for our matching variables and urbanicity. Results: We observed significant positive associations between diagnosis of dementia and increased PM2.5 (OR 1.18; 95%CI 1.09-1.28) per 1 µg/m3, and for relative humidity (OR 1.06; 95%CI 1.01-1.11) per 1%. Air and apparent temperature showed similar patterns (OR 1.16; 95% CI 0.99-1.35 and OR 1.17; 95%CI 1.02-1.34) per 1°C. Conclusion: Our findings indicate that there are associations between both PM2.5 and year prior heat exposures and dementia. These findings suggest that further investigation into the role of heat and dementia is warranted. This abstract does not reflect EPA policy.   

Impact/Purpose

Dementia is a serious health concern, especially for older adults, as it greatly impacts quality of life and cognitive and functional abilities. Dementia may be impacted by environmental factors, but the research on environmental risk factors for dementia is limited. PM2.5 air pollution has been identified as a possible risk factor; heat exposure is also plausibly related to dementia. Health effects of heat exposure are becoming increasingly important due to climate change. In this study, we examined associations between temperature, relative humidity, and PM2.5 exposures on dementia in a medical records cohort. We observed potential associations between increased annual PM2.5 concentration, apparent temperature, air temperature, and relative humidity with dementia diagnosis.

Citation

Weaver, A., E. Slawsky, C. Ward-Caviness, AND J. Moyer. Heat, Fine Particulates, and Diagnosis of Dementia: A matched Case Control Study in North Carolina from 2003 to 2016. International Society of Environmental Epidemiology, Athens, GREECE, September 18 - 21, 2022.