A longitudinal study of cortisol responses, sleep problems, and psychological well-being as the predictors of changes in depressive symptoms among breast cancer survivors

Objective: This study examined whether the changes in sleep problems, attachment styles, meaning in life, and salivary cortisol over the course of 14 months were the predictors of changes in depressive symptoms in women with breast cancer at post-treatment stage. Methods: The study included 76 participants who completed active breast cancer treatment with longitudinal data collected at five points, including baseline assessment (TO) and the four follow-ups after baseline: T1 (in the 2nd month), T2 (in the 5th month), T3 (in the 8th month), and T4 (in the 14th month). The self-reported questionnaires included the Medical Outcomes Study Sleep (MOS-Sleep) scale; the Beck Depression Inventory-II (BDI-II); the Experiences in Close Relationships-Revised (ECR-R) scale for measuring anxiety and avoidance dimensions of attachment style; and the Meaning in Life Questionnaire (MLQ), consisting of the MLQ-Presence scale and the MLQ-Search scale. The participants collected their salivary cortisol at home at six time points: upon waking, 30 and 45 min after waking, and at 1200 h, 1700 h, and 2100 h. Results: Higher scores on for anxiety-related attachment style and the sleep problems index at baseline were associated with more severe initial depressive symptoms after the age, BMI, cancer, and treatment variables were controlled. The presence of meaning in life at baseline was negatively correlated with initial depressive symptoms. Moreover, the decreases in the presence of meaning in life over the course of 14 months predicted more severe depressive symptoms. In addition, the persistent increases of cortisol level at 2100 h across 14-month follow-ups predicted worsening depressive symptoms. Conclusions: Lacking presence of meaning in life as a predictor for severe depressive symptoms demonstrates that breast cancer survivors who lack psychological well-being are more likely to be depressed. The persistent elevation of cortisol levels at night also indicates breast cancer survivors to be at high risk of depression. (C) 2012 Elsevier Ltd. All rights reserved.