Association between anemia and depression: results from NHANES 2005–2018 and mendelian randomization analyses

Background The relationship between anemia and depression remains controversial. Objective To explore the association between anemia/hemoglobin and depression. Methods The data for our cross-sectional study were obtained from the National Health and Nutrition Examination Survey (NHANES) 2005–2018. Weighted multivariate logistic regression was performed to examine the association between anemia/hemoglobin and depression. Inverse variance weighted (IVW), weighted-median, and MR-Egger were used in MR analyses to assess the causal relationship between anemia/hemoglobin and depression. Heterogeneity and directional pleiotropy were assessed using the Cochrane Q test and Egger-intercept test, respectively. Sensitivity analysis was conducted by the leave-one-out approach. All analyses were carried out using IBM SPSS 24.0 and R version 4.2.2. Results A total of 29,391 NHANES participants were included in this study. After adjusting for all covariates, the association between anemia/hemoglobin and depression was not significant ( P