ABSTRACT
BACKGROUND: Rumination is strongly associated with depressive symptom severity and course. However, changes in rumination during outpatient cognitive behavioral therapy (CBT), and their links to baseline features such as distress tolerance and clinical outcomes, have received limited attention. METHODS: 278 outpatients with depression received group or individual CBT. Measures of rumination, distress tolerance, and depression symptom severity were assessed at baseline and periodically during treatment. Mixed effect and regression-based models evaluated changes over time, and associations between rumination, distress tolerance and depression severity. RESULTS: Depression and rumination decreased throughout acute treatment. Rumination reduction was concurrently associated with depressive symptom reduction. Lower levels of rumination at each time point prospectively predicted lower depressive symptoms at the next time point. Distress tolerance measured at baseline was positively associated with depression symptom severity; the indirect effect on post-treatment depression symptoms via rumination measured mid-treatment was nonsignificant when rumination at baseline was accounted for. Changes in and associations between depression and rumination were replicated in sensitivity analyses; although changes in depression and rumination were smaller in magnitude in patients receiving treatment during COVID-19. LIMITATIONS: Additional assessment points would permit a more nuanced assessment of the role rumination may play in mediating the associations between distress tolerance and depression severity. Additional investigation of treatments in community settings may also further our understanding of variability in rumination during depression treatment. CONCLUSIONS: The current study provides unique real-world support for variability in rumination as a key indicator of change over the course of CBT for depression.
