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.