Background: Depression has been associated with increased risk of cardiovascular disease. The inflammatory marker C-reactive protein (CRP) has also been identified as an independent predictor of short- and long-term cardiovascular disease events. Inflammation may influence the relationship between depression and cardiovascular disease.
Objective: The objective of this study was to investigate the association between symptoms of depression and high-sensitivity CRP (hs-CRP) in an obese clinical population. We also sought to determine whether this relationship was different in men and women, given prior reports of a gender effect.
Methods: Symptoms of depression and hs-CRP were measured in 390 participants enrolled in a weight loss intervention trial that was delivered in a primary care setting. Symptoms of depression were evaluated with the Patient Health Questionnaire-8 (PHQ-8), in which a score ≥ 10 is consistent with major depression.
Results: A total of 58 (15.2%) participants reported a PHQ-8 score ≥ 10. The median (interquartile range) hs-CRP concentration was significantly higher in participants with symptoms consistent with major depression (7.7 (4.2-13) mg l(-1)) compared with those without depression (5.1 (3-9.7) mg l(-1); P<0.01). Symptoms consistent with major depression were significantly associated with log-transformed hs-CRP concentrations in an analysis adjusted for age, gender, obesity class and other metabolic variables (P=0.04). When interaction by gender was examined, this relationship remained significant in men (P<0.01) but not in women (P=0.32).
Conclusions: Symptoms consistent with major depression were significantly associated with hs-CRP in men only, even after adjusting for age, obesity class, metabolic variables and medications known to affect inflammation. This finding suggests that there are biologic differences between men and women that may modify the relationship between hs-CRP and depression. Further studies are needed to elucidate the biologic basis for these findings.