Association between combined exposure to atmospheric and water environment and memory-related disease risk in middle-aged and elderly: based on the CHARLS database

Evidence regarding the combined associations of air pollution and water environmental quality with memory-related diseases remains limited. This study investigated the individual and combined associations of atmospheric and water indicators with memory-related disease. Data from 15,071 participants in the China Health and Retirement Longitudinal Study (CHARLS; 2013–2018) were analyzed, including 571 newly reported cases of self-reported or proxy-reported physician-diagnosed memory-related disease. Six air pollutants (PM₂.₅, PM₁₀, SO₂, NO₂, CO, and O₃) and four water quality indicators (pH, dissolved oxygen [DO], ammonia nitrogen [NH₄-N], and permanganate index [CODMn]) were assigned using province-level annual averages. Generalized estimating equations (GEE), quantile g-computation (qgcomp), and weighted quantile sum (WQS) regression were used to evaluate individual and mixture associations. Nonlinear relationships, subgroup differences, and robustness were also examined. In the fully adjusted GEE model, each interquartile range increase in CODMn (OR = 1.24, 95% CI: 1.11–1.39), DO (OR = 1.18, 95% CI: 1.04–1.35), NH₄-N (OR = 1.06, 95% CI: 1.02–1.09), PM₂.₅ (OR = 1.28, 95% CI: 1.07–1.52), PM₁₀ (OR = 1.35, 95% CI: 1.16–1.58), NO₂ (OR = 1.14, 95% CI: 1.00–1.29), CO (OR = 1.23, 95% CI: 1.03–1.47), and O₃ (OR = 1.30, 95% CI: 1.08–1.56) was associated with higher odds of newly reported memory-related disease. The qgcomp analysis indicated a positive overall mixture association (OR = 1.44, 95% CI: 1.13–1.84), consistent with WQS findings for the air pollutant mixture (OR = 1.20, 95% CI: 1.04–1.38) and regional surface-water indicator mixture (OR = 1.15, 95% CI: 1.01–1.31). RCS analyses suggested nonlinear associations for selected indicators, while no subgroup interactions remained significant after false discovery rate correction. Sensitivity analyses generally supported the direction of the primary findings. Several atmospheric and regional surface-water environmental indicators, individually and in combination, were associated with higher odds of newly reported physician-diagnosed memory-related disease among middle-aged and older Chinese adults. These findings highlight the importance of considering multiple environmental indicators in research on memory-related health outcomes and warrant further investigation using more precise exposure assessments and clinically validated outcomes.