Background: Negative self-referential processing has fruitfully been studied in unipolar depressed patients, but remarkably less in patients with bipolar disorder (BD). This study examines the relation between task-based self-referential processing and depressive symptoms in BD and their possible importance to the working mechanism of mindfulness-based cognitive therapy (MBCT) for BD.Methods: The study population consisted of a subsample of patients with BD (n = 49) participating in an RCT of MBCT for BD, who were assigned to MBCT+TAU (n = 23) or treatment as usual (TAU) (n = 26). Patients performed the self-referential encoding task (SRET), which measures (1) positive and (2) negative attributions to oneself as well as (3) negative self-referential memory bias, before and after MBCT. Results: At baseline all three SRET measures were significantly related to depressive symptoms in patients with BD. Moreover, repeated measures analyses of variance revealed that negative self-referential memory bias diminished over time in the MBCT+TAU group, compared with the TAU group. Conclusions: Task-based self-referential processing is related to depressive symptoms in BD. Moreover, the negative self-referential memory bias was specifically amenable to change through MBCT. Future research should explore the possibly mediating role of reduction of negative self-referential memory bias in preventing and treating depressive symptoms in BD through MBCT.

Background: Preliminary evidence suggests that Mindfulness-Based Cognitive Therapy (MBCT) is a promising treatment for bipolar disorder (BD). One of the proposed working mechanisms of MBCT in attenuating depressive symptoms is through the reduction of depressive rumination. In BD the effect of MBCT on rumination is less well studied. The primary aim of this study was to investigate the effect of MBCT on self-reported trait depressive rumination and an experimental state measure of negative intrusive thoughts. On an exploratory note, we investigated the effect of MBCT on positive rumination and positive intrusive thoughts.Methods: The study population consisted of a subsample of bipolar type I or II patients participating in a multicenter randomized controlled trial comparing MBCT + treatment as usual (TAU) (N = 25) to TAU alone (N = 24). Trait depressive rumination (RRS brooding subscale) and negative intrusive thoughts (breathing focus task (BFT)) were assessed at baseline and post-treatment. During the BFT, participants were asked to report negative, positive and neutral intrusive thoughts while focusing on their breathing. Results: Compared to TAU alone, MBCT + TAU resulted in a significant pre- to post-treatment reduction of trait depressive rumination (R2 = 0.16, F(1, 28) = 5.30, p = .029; medium effect size (f2 = 0.19)) and negative intrusive thoughts on the BFT (R2 = .15, F(1, 28) = 4.88, p = .036; medium effect size (f2 = 0.17)). MBCT did not significantly change positive rumination or positive intrusive thoughts on the BFT.Conclusions: MBCT might be a helpful additional intervention to reduce depressive rumination in BD which might reduce risk of depressive relapse or recurrence. Future research is required to replicate our findings and to explore whether this reduction in rumination following MBCT indeed mediates a reduction in depressive symptoms and leads to relapse prevention in BD.