Depressive symptoms and levels of C-reactive protein: a population-based study.

Background: Depression and depressive symptoms have been repeatedly linked to elevated levels of C-reactive protein (CRP) but questions remain as to the statistical robustness of the association and particularly whether the association between depression and CRP reflects the presence of a chronic disease.

Methods: A random sample of 6,126 men and women aged 45-69 years was examined in a cross-sectional study in seven towns in the Czech Republic. Depressive symptoms were assessed by the Center for Epidemiologic Studies Depression (CESD) scale.

Results: Center for Epidemiologic Studies Depression score was significantly related to increased levels of CRP in a linear fashion. After controlling for a range of potential confounders, subjects with depressive symptoms (CESD score >or= 16) had CRP concentrations 0.43 mg/l (95% CI 0.16-0.72) higher than those without symptoms. The association remained significant when study sample was restricted to healthy subjects; among individuals who did not report any chronic disease, the difference between those with and without depressive symptoms was 0.44 mg/l (95% CI 0.14-0.74), and among persons who did not visit a doctor in the last 12 months the difference was 1.20 mg/l (95% CI 0.52-1.87).

Conclusions: These results confirm that there is a statistically robust association between depressive symptoms and increased levels of CRP. We did not find evidence that the association is due presence of a chronic condition.