Satellite-based evidence for heatwave-driven MCI-to-dementia transitions.

This study aimed to provide satellite-based evidence on the potential role of heatwave exposure in the transition from mild cognitive impairment (MCI) to dementia by examining whether heatwave exposure statistically modifies the association between MCI and dementia prevalence using repeated district-level observations collected annually from 228 administrative districts across South Korea between 2015 and 2023. Satellite-derived land surface temperature from the Moderate Resolution Imaging Spectroradiometer (MODIS) thermal imagery was used as a proxy for heatwave exposure. Interaction-based modeling was implemented by multiplying MCI prevalence by summer temperature to construct interaction terms. Heatwave exposure, MCI prevalence, and their interaction term were specified as independent variables in a geographically and temporally weighted regression (GTWR) model, with dementia prevalence serving as the dependent variable. The results revealed spatial variation in how heatwave exposure moderates the MCI-dementia progression, particularly in districts where the proportion of older adults exceeded 25%, suggesting an accelerated transition to dementia in these areas. Although this study focused on South Korea, the findings may offer relevant insights for other countries into how heatwave exposure interacts with regional patterns of dementia risk.