Associations Among Irritability, High-Sensitivity C-Reactive Protein/Interleukin-6, and Depression in Patients With Early-Stage Breast Cancer Undergoing Chemotherapy: A Prospective Study

Background Association between irritability and depression has been frequently reported, but the nature of this association in the adult population is poorly understood. Objectives We examined associations among irritability (e.g., a feeling of agitation), inflammatory biomarkers, and depression during chemotherapy. Methods Forty-four patients with nonmetastatic breast cancer were assessed at baseline and after 3 months of chemotherapy on The Irritability Scale-Initial Version, severity and new onset of depressive symptoms using the Hamilton Depression Rating Scale, and serum levels of high-sensitivity C-reactive protein and interleukin 6. Results At baseline, high-sensitivity C-reactive protein significantly correlated with physical and mood subscales of The Irritability Scale-Initial Version, but not with depression. Irritability and high-sensitivity C-reactive protein significantly predicted the severity and new onset of moderate to severe depressive symptoms over time, while irritability and interleukin 6 significantly predicted new onset of moderate to severe depressive symptoms. Conclusion The findings suggest that irritability is an independent risk factor of depression and associated with increasing high-sensitivity C-reactive protein. Irritability needs to be effectively managed in patients with cancer undergoing chemotherapy to prevent them from developing depressive symptoms. These preliminary findings should be investigated in future large-sample studies.