The Association Between Anemia and Depressive Symptoms in Non-White Male Adults: National Health and Nutrition Examination Survey (2005-2018)

Background: The relationship between anemia and depression remains controversial. This study aimed to investigate the association between hemoglobin (Hb) levels and depressive symptoms. Study Design: A cross-sectional study. Methods: This study was conducted using National Health and Nutrition Examination Survey data from 2005-2018. Hb levels were obtained from laboratory files, and depressive symptoms were assessed using the Patient Health Questionnaire (PHQ-9). Multivariable logistic regression analysis and smoothing plots were performed to examine the relationship between anemia and depression, including potential nonlinear associations. Results: The study included 6008 male adults. Multivariable analysis revealed that anemia was associated with an increased odds ratio for mild (OR = 1.49, 95% CI: 1.06, 2.10) and moderate (OR = 2.05, 95% CI: 1.14-3.70) anemia. Additionally, each additional g/dL of Hb was significantly inversely associated with developing depression (OR = 0.91, 95% CI: 0.85, 0.96). A nonlinear relationship was detected between Hb and depression, with an inflection point at 15 g/dL. Below this threshold, there was a significantly negative association between Hb and depression (OR = 0.88, 95% CI: 0.79, 0.98); no significant relationship was observed above it (OR = 1.05, 95% CI: 0.84, 1.31). Conclusion: Anemia was positively associated with depression in non-White American men. A nonlinear relationship between Hb and depression was detected, and it had a saturation effect. A significant negative correlation with depression was observed when the Hb level was below 15 g/dL.