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.