Relationship of solid fuels use with cognitive function and efficacy of switching to cleaner fuels or using ventilation: A systematic review and meta-analysis

A growing number of studies have examined the relation between solid fuels use and cognitive function in the mid-elderly, but results are inconsistent. Therefore, a systematic review and meta-analysis was carried out to evaluate their relevance and the efficacy of switching to cleaner fuels or using ventilation. We used PubMed, Web of Science, and Cochrane Library databases to identify 17 studies in which the primary outcome variable was cognitive function decline or cognitive disorders, and the exposure measure was solid fuels use. The final search date of August 31, 2023. The effect size of odds ratio (OR), regression coefficient (β), and 95% confidence interval (CI) were pooled. Heterogeneity and the possibility of publication bias were assessed by using the Q-statistic and Begg's test, respectively. Among the 17 included papers, the study participants were ≥45 years old. Eleven studies assessed the relationship between solid fuels use and cognitive function decline [number of studies (n) = 11, β = −0.144; I2 = 97.7%]. Five studies assessed the relationship between solid fuels use and cognitive disorders (n = 5, OR = 1.229; I2 = 41.1%). Switching from using solid fuels to clean fuels could reduce the risk of cognitive function decline as compared to those who remained on using solid fuels (n = 2; β = 0.710; I2 = 82.4%). Among participants using solid fuels, who cooked without on ventilated stoves were correlated with an enhanced risk of cognitive disorders as compared to participants who cooked with ventilated stoves (n = 2; OR = 1.358; I2 = 44.7%). Our meta-analysis showed a negative relationship between solid fuels use with cognitive function, and a positive relationship with cognitive disorders. Cleaner fuels, using ventilation, improved cookstoves can reduce the adverse health hazards of solid fuels use.