Background: This study examined whether mild-to-moderate depressive symptoms are associated with increased high-sensitivity C-reactive protein (hsCRP) and interleukin 6 (IL-6) levels in apparently healthy individuals at high risk for coronary artery disease. We investigated in individuals whether: (1) current depressive symptoms were associated with increased hsCRP and IL-6 levels; (2) persistent depressive symptoms at two time points 6 months apart were associated with hsCRP and IL-6; and (3), sex-based differences in inflammation were a function of depressive symptoms.
Methods: We measured depressive symptoms (twice), hsCRP, and IL-6 (follow-up time point) in 84 apparently healthy individuals (52% women) at high cardiac risk.
Results: Patients with persistent depressive symptoms had higher hsCRP, compared to participants without persistent symptoms (5.55 vs. 1.70 mg/l, p < 0.05, 95% CI 0.11 to 1.09, d = 0.67). Participants with current depressive symptoms had higher hsCRP (3.99 vs. 1.70 mg/l, p = 0.059) than those without symptoms. Findings remained unchanged after controlling for covariates. Women had higher adjusted hsCRP than men (2.91 vs. 1.87 mg/l, p < 0.001). When we entered depressive symptoms, the model remained significant, with a significant interaction between sex and symptoms: women with depressive symptoms had higher hsCRP than men with depressive symptoms and than women without symptoms (6.75 vs. 1.11 mg/l). The hypothesized differences were not observed with respect to IL-6, after controlling for body mass index (95% CI-0.77 to 0.73).
Conclusions: Before a first ischaemic coronary event, persistent mild-to-moderate depressive symptoms were associated with increased hsCRP. Women with depressive symptoms had higher hsCRP than men with symptoms.