BackgroundPrior research has established a connection between depression and chronic obstructive pulmonary disease (COPD). However, the influence of age and BMI on this association remains unclear. ObjectivesWe used the National Health and Nutrition Examination Survey (NHANES) database to explore the relationship between depression and COPD, and to investigate whether age and Body mass index (BMI) act as moderators in this relationship. MethodsWe analyzed data from 10,940 participants in the NHANES database. Depression served as the independent variable. COPD status served as the outcome variable. We employed multivariable logistic regression to examine the relationship between depression and COPD. ResultsOf the 10,940 respondents surveyed, about 3.9 % had COPD and 8.5 % had depression. The prevalence of depression in COPD patients was significantly greater than the prevalence of overall respondents (21.1 % VS.8.5 %). We found that the association between depression and COPD was mediated by BMI status. Controlling for other covariates, the association between depression and COPD increased significantly. For the underweight group, the impact of depression on the risk of COPD was lower compared to the normal BMI group. ConclusionThis study confirms a significant association between depression and COPD, with BMI serving as a moderator. These findings enhance our understanding of the complex interplay between depression and COPD and underscore the importance of considering individual physical health characteristics in clinical assessments. The results have significant implications for clinical practice and public health policymaking.