Depressive symptoms and levels of C-reactive protein

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. 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. 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 a parts per thousand yen 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). 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.