Association between Solid Cooking Fuel Use and Dementia in Middle Aged and Older Adults: Depression as a Mediator

Abstract

BackgroundPrevious studies have shown that solid fuel use is associated with cognitive impairments. However, the impact of indoor air pollution on the prevalence of dementia remains unclear. The influence factors of this association are also unknown. Thus, this study aimed to explore the association between household solid cooking fuel use and dementia prevalence and the possible mediating effects of depression and pulmonary factors on this association.MethodsA total of 5256 (wave 4) and 2289 (wave 4 back to wave 3) participants from the China Health and Retirement Longitudinal Study (CHARLS) were enrolled in the cross-sectional and retrospective longitudinal analyses, respectively. We identified dementia using the abbreviated Community Screening Instrument for Dementia (CSI-D) with a combination of informant parts. The effects of solid cooking fuel use (including baseline fuel type and switching cooking fuel types) on dementia were examined using logistic regression adjusting for potential confounders. The mediating effect of depression was detected using a structural equation model.ResultsSolid cooking fuel use was associated with a higher prevalence of dementia in the wave-4 cross-sectional (OR = 1.74, 95%CI [1.52, 1.99], P < 0.001) and wave3-to-wave4 follow-up studies (OR = 1.99, 95%CI [1.61, 2.48], P < 0.001). Solid cooking fuel affected dementia partially through depression, and the indirect effect explained 9.38% and 10.20% variances in the cross-sectional and longitudinal mediating model, respectively. A history of chronic lung diseases and peak expiratory flow (PEF) showed no mediating effects on the cooking fuel-dementia association.ConclusionsHousehold solid cooking fuel use is a risk factor for the development of dementia. Depressive symptoms, instead of lung diseases or PEF, partially explained this association. It is possible to reduce the prevalence of dementia by improving the fuel structure and depressed moods in middle-aged and older adults.

Keywords: dementia, Solid fuel use, Indoor Air Pollution, depression, Pulmonary function, Longitudinal design