Abstract # 3115 Chemotherapy, bacterial translocation, heart rate variability, and depression in breast cancer survivors

Abstract

While psychosocial factors are powerful predictors of depression in cancer patients, objective measures (e.g., chemotherapy treatment length and type) have been inconsistently linked to depression. Even so, several studies have found higher rates of depression among chemotherapy patients. The kynurenine pathway has been proposed as an inflammation-mediated link between chemotherapy and depression. The current study proposed and tested another pathway from chemotherapy to depression. Breast cancer survivors (N = 143) were recruited for the parent study – a yoga clinical trial. At the baseline visit, women had blood drawn, completed the CES-d, and engaged in relaxation while heart rate variability (HRV) was measured. Chemotherapy patients (n = 87) had greater serum CD14 (p = 0.032), an index of bacterial translocation and intestinal permeability. Additionally, women with higher levels of serum CD14 exhibited lower HRV (p = 0.049) – consistent with mechanistic animal studies. Finally, lower HRV was associated with greater depressive symptoms (p = 0.018). A double mediation model was tested, with chemotherapy leading to serum CD14 leading to HRV leading to depressive symptoms. Controlling for age, sagittal abdominal diameter, beta blocker use, tamoxifen, and radiation, a complete mediation emerged, whereby women who received chemotherapy had greater depressive symptoms when both serum CD14 and heart rate variability were included as mediators (CI: 0.0043–0.4690). Results suggest a novel bottom-up pathway from chemotherapy to depression.