Explaining age-related differences in depression following breast cancer diagnosis and treatment.

Younger women with breast cancer consistently show greater psychological distress than older women. This study examined a range of factors that might explain these age differences. A total of 653 women within 8 months of a first-time breast cancer diagnosis provided data on patient characteristics, symptoms, and psychosocial variables. Chart reviews provided cancer and treatment-related data. The primary outcome was depressive symptomatology assessed by the Beck Depression Inventory. A succession of models that built hierarchically upon each other was used to determine which variables could account for age group differences in depression. Model 1 contained age group only. Models 2-5 successively added patient characteristics, cancer-related variables, symptoms, and psychosocial variables. As expected, in the unadjusted analysis (Model 1) younger women were significantly more likely to report depressive symptomatology than older women (p < 0.0001). Age remained significantly related to depression until Model 4 which added bodily pain and vasomotor symptoms (p = 0.24; R (2) = 0.27). The addition of psychosocial variables in Model 5 also resulted in a model in which age was nonsignificant (p = 0.49; R (2) = 0.49). Secondary analyses showed that illness intrusiveness (the degree that illness intrudes on specific areas of life such as work, sex life, recreation, etc.) was the only variable which, considered individually with age, made the age group-depression association nonsignificant. Age differences in risk of depression following a breast cancer diagnosis can be explained by the impact of cancer and its treatment on specific areas of a woman's life.