Systemic Low-grade Inflammation and depressive symptomology at chronic phase of ischemic stroke: The Chain Mediating Role of Fibrinogen and Neutrophil counts.

Abstract Background Post-stroke depression (PSD) is the most common psychological consequence among stroke patients. Increased inflammatory markers resulted from ischemic stroke probably played an important role in pathogenesis of depressive symptomology. We aimed to determine the relationship among stroke severity, systemic low-grade inflammation and depressive symptomology. Methods A total of 897 patients were consecutively recruited in this prospective cohort study and followed up for 1 year. The sample consisted of 436 ischemic stroke patients (23.4% female, median age = 57 years) from this cohort. Serum concentrations of inflammatory markers were measured in all 436 ischemic stroke patients, from fasting morning venous blood draws on admission. Stroke severity was evaluated by National Institutes of Health Stroke Scale (NIHSS) on admission and post-stroke depressive symptomology were evaluated by 17-item Hamilton Rating Scale for Depression (HRSD) at 1 year after ischemic stroke. Results After fully adjusted for covariates, we observed that 1) NIHSS (Model 2: β=0.200, 95%CI, 0.057∼0.332), fibrinogen (Model 2: β=0.828, 95%CI, 0.269∼1.435), WBC (Model 2: β=0.354, 95%CI, 0.122∼0.577) and neutrophil count (Model 2: β=0.401, 95%CI, 0.126∼0.655) can independently predict the 1-year depressive symptomology after ischemic stroke; 2) fibrinogen (Indirect effect=0.027, 95%CI, 0.007∼0.063, 13.4% mediated), white blood count (WBC, Indirect effect=0.024, 95%CI, 0.005∼0.058, 11.8% mediated) and neutrophil counts (Indirect effect=0.030, 95%CI, 0.006∼0.069, 14.8% mediated) could partially mediated the association between stroke severity (NIHSS) and 1-year depressive symptomology, and 3) stroke severity might cause depressive symptomology partly through the chain mediating role of both fibrinogen and neutrophil count (chain mediated effect=0.003, 95%CI, 0.000∼0.011, p=0.025, 1.6% mediated). Conclusions These results suggested that fibrinogen, WBC and neutrophil count in systemic low-grade inflammation might be significant predictors of 1-year post stroke depressive symptomology and partial mediators of the relationship between stroke severity and 1-year depressive symptomology among ischemic stroke patients. In addition, the chain mediating effect of fibrinogen and neutrophil count might play an important role in the occurrence of 1-year post stroke depressive symptomology. However, no inflammatory marker was associated with 1-year depressive symptomology in females.