Objective To investigate the relationship between e-cigarette use and subjective cognitive decline.

Methods This study included survey participants aged ≥45 years from the US Behavioral Risk Factor Surveillance System. The prevalence of subjective cognitive decline in people with different tobacco use conditions was estimated. Multivariate logistic regression was employed to determine the relationship between e-cigarette use and subjective cognitive decline， as well as the relationship between co-use of e-cigarette and combustible tobacco and subjective cognitive decline.

Results A total of 204 032 participants were included in the study. The total prevalence of subjective cognitive decline was 11.46%， whereas among current e-cigarette users， the prevalence was 19.92%. After accounting for confounding factors， current e-cigarette use was identified as a risk factor for subjective cognitive decline compared to individuals who had never used e-cigarettes， with an OR of 1.46 （95%CI： 1.20‒1.77）. Meanwhile， occasional e-cigarette use showed a higher risk， with an OR of 1.54 （95%CI： 1.22‒1.95）. The highest risk was observed with the co-use of e-cigarette and combustible tobacco， with an OR of 1.69 （95%CI： 1.32‒2.16）， followed by current e-cigarette use and former combustible tobacco use， with an OR value of 1.38 （95%CI： 1.08‒1.78）.

Conclusion The use of e-cigarettes increases the risk of subjective cognitive decline， with occasional use demonstrating a more pronounced negative impact. In general， the risk of cognitive decline is greater among e-cigarette users compared to combustible tobacco users. Controlling the use of combustible tobacco， especially e-cigarette， will help reduce the incidence of subjective cognitive decline. Individuals currently using combustible tobacco are advised to explore smoking cessation methods other than transitioning to e-cigarettes.