The Association Between Obesity and Depressive Symptoms: Mediation by C-Reactive Protein and Neutrophil-to-Lymphocyte Ratio.

Background: Obesity and depressive disorders are significant public health concerns, and their association is well-documented. This study investigates the role of inflammatory markers, specifically C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), in mediating the relationship between obesity and depressive symptoms.

Methods: We utilized data from 37,538 adults from the National Health and Nutrition Examination Survey (NHANES), covering the period from 2005 to March, 2020, pre-pandemic. Depressive symptoms were measured using the Patient Health Questionnaire-9 (PHQ-9), while inflammatory markers were assessed via NLR and CRP levels.

Results: Results indicated a positive correlation between obesity, NLR, and CRP levels, and depressive symptoms. Notably, CRP exhibited a significant mediating effect in the obesity and depressive symptoms link, whereas NLR did not. (NLR: 0.0926%, p = 0.740; CRP: 32%, p < 0.001). Furthermore, the mediating effect of CRP in the male group was significantly higher than in the female group (Men: 57%, p < 0.001; Women: 16%, p = 0.046).

Conclusion: These findings provide new insights into the mechanisms linking obesity and depressive symptoms, especially in men, and may guide future therapeutic strategies.