Vulnerability to inflammation-related depressive symptoms: Moderation by stress in women with breast cancer.

Background: Stress precipitates depression and may do so in part by increasing susceptibility to inflammation-induced depressive symptoms. However, this has not been examined among individuals facing a major life stressor. Accordingly, the present study tested the moderating role of stress on the longitudinal association between inflammation and depressive symptoms among women with breast cancer.

Methods: Women recently diagnosed with early-stage breast cancer (N = 187) were enrolled before starting adjuvant/neoadjuvant treatment. Blood draws and self-reported depressive symptoms were collected pre-treatment, post-treatment, and at 6, 12, and 18-month post-treatment follow ups. C-reactive protein (CRP) was used to index inflammation. Measures of psychological stress, including cancer-related stress, general stress perceptions, and childhood stress, were administered pre-treatment.

Results: Stress moderated the association between CRP and depressive symptoms, such that higher levels of CRP were associated with elevated depressive symptoms only among women who reported high cancer-related stress (β = 0.080, p = .002) and perceived stress (β = 0.053, p = .044); childhood stress effects were non-significant. Moreover, elevated CRP was associated with increased odds of exhibiting clinically significant depressive symptoms (OR = 1.64, p < .001) among women who reported high cancer-related stress. Results were independent of age, BMI, race and cancer-related covariates.

Conclusions: Stress was found to heighten sensitivity to inflammation-associated depressive symptoms over a 2-year period, with notably stronger effects for subjective stress responses to a concurrent life event. Individuals who are most distressed following a major life event may exhibit the greatest risk for inflammation-induced depression.