Mindfulness-Based Cognitive Therapy (MBCT) is effective in reducing relapse rates and (residual) symptoms in major depressive disorder (MDD). However, the mechanisms underlying those MBCT-induced effects are far from clear. The goal of this study is to get more insight into the working mechanisms of MBCT. The main question to be answered is whether MBCT-induced reduction in depressive symptoms is mediated and/or moderated by repetitive negative thinking (RNT), or other factors hypothesized to be involved in the working mechanism of MBCT (e.g. mindfulness skills and self-compassion).
Introduction Depression is highly prevalent and is ranked by the world health organization (WHO) as the number one contributor to disability worldwide. The highly recurrent nature of the disorder contributes greatly to the burden of Major Depressive Disorder (MDD) and with every new depressive episode, outcome prospective worsen. Mindfulness Based Cognitive Therapy (MBCT) is an effective treatment to reduce relapse rates and (residual) symptoms that contribute to recurrence in MDD. However, the mechanisms underlying this MBCT-induced effect are far from clear. Elucidating these mechanisms will provide insight in the existing individual differences in effectiveness of MBCT. Consequently, this insight will help to improve effectiveness of treatment and even personalize treatment regimes. One likely candidate that could play a major role in the positive effects of MBCT on depressive symptoms, is repetitive negative thinking (RNT). Depressive rumination is the most well-studied form in the context of depression and has been described as the process of thinking perseveratively about one's feelings and problems (such as symptoms of depression) and their possible causes and consequences. It is believed that during MBCT participants develop the ability to become aware of automatic maladaptive cognitive processes such as depressive rumination, and learn to decenter and disengage from them. Because of this core skill to be learned during MBCT patients may be prevented to enter a vicious cycle of ruminative thinking that could otherwise aggravate symptoms of depression or have resulted in a new depressive episode. Objectives Our main objectives are (i) to replicate the beneficial effects of MBCT on depressive symptoms and RNT in patients with chronic or recurrent depression (crMDD), and (ii) to investigate whether individual levels of RNT (iia) mediate and/or (iib) moderate the MBCT-induced reduction in depressive symptoms. To this end self-report questionnaires of depressive symptoms, content-independent RNT and depressive rumination will be administered before, half-way and after MBCT (intervention group) or before, half-way and after a waiting-period (waitlist group). Secondary objectives To triangulate research findings an experimental task (breathing focus task) that measures intrusive thoughts during task performance will be administered. Moreover, research will focus on cognitive control and affective biases therein, because this process is related to RNT. Two major constituents of cognitive control will be measured, i.e. working memory processing and motivational biases of cognitive control (with respectively a working-memory update/ignore emotion task and Pavlovian-to-instrumental transfer task) before and after MBCT/waitlist. This behavioural data will be used to assess whether working memory and motivational biases are indeed (i) related to RNT and MDD, (ii) are changed by MBCT and (iii) whether these changes are related to clinical effects of MBCT. Additionally, the timing of change will be investigated by administering weekly self-report questionnaires. Design: A multicenter, wait-list controlled-trial, with assignment to an intervention group (MBCT + treatment as usual (TAU)) or waitlist-control group (TAU) based on date of intake and start date of MBCT. Thus, assignment is not randomized and the study does not interfere with regular clinical practice (e.g. planning MBCT). If patients have to wait \> 7 weeks for the next MBCT, they are invited to participate in the wait-list group while patients that have to wait \< 7 weeks will be assigned to the intervention group. Note that although a full MBCT-training training lasts 8 weeks, for feasibility a cut-off of 7 weeks instead of 8 was deliberately chosen because this allows us to assign more patients to the wait-list group. This was done to prevent (as much as possible) an anticipated skewed allocation in favour of the intervention group. Healthy controls will be invited to one measurement as a benchmark for the innovative cognitive tasks and do not follow MBCT. Statistical analysis: A detailed description of the planned analyses can be found within the attached Statistical Analysis Plan.
MBCT will be offered according to the MBCT manual developed for relapse prevention in MDD (Zindel V. Segal, Williams, \& Teasdale, 2002). Thus, MBCT will consist of 8-weekly sessions of 2,5 hours, a 6-hour silent day, and daily home practice (± 45min). MBCT will be taught by a certified MBCT teacher meeting the advanced criteria of the Association of Mindfulness Based Teachers in the Netherlands and Flanders (Belgium) which are in concordance with the Good Practice guidelines of the UK Network of Mindfulness-Based Teacher Trainers (Crane et al., 2012).
Pro Persona
Nijmegen, Gelderland, Netherlands
Radboud University Medical Centre
Nijmegen, Gelderland, Netherlands
Depressive symptoms
Measured with the Inventory of Depressive Symptomatology Self-Report (IDS-SR). The IDS-SR consists of 30 items. Scores range from 0-84. Higher scores indicate a higher severity of depression.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Depressive rumination
Measured with the brooding subscale of the Ruminative Response Scale (RRS). The brooding subscale consists of 5 items. Scores range from 5-20. Higher scores indicate a higher level of depressive rumination.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Repetitive negative thinking (RNT)
Measured by the Perseverative Thinking Questionnaire (PTQ). The PTQ consists of 15 items. Scores range from 0-60. Higher scores indicate a higher level of repetitive negative thinking.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Intrusive thoughts (state measure)
Measured with the breathing focus task (BFT) that measures negative, positive and neutral thoughts during task performance
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Mindfulness Skills
Measured with the Five Facet Mindfulness Questionnaire - Short Form (FFMQ-SF). This questionnaire is divided into the subscales observing (4 items), and describing, acting with awareness, non-judging and non-reactivity (all 5 items). The facets scores will be calculated by determining the mean of corresponding item scores. Negatively-phrased items will be reversed scored before computing the mean scores of the subscales. Subscale scores range from 1-5, with higher scores indicating 'higher/better' ability of mindfulness on the corresponding domain.
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Study Type
OBSERVATIONAL
Enrollment
135
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Anxiety Symptoms
Measured with the Spielberger State-Trait Anxiety Inventory (STAI). The STAI consists of 20 items. Scores range from 20-80. Higher scores indicate a higher severity of anxiety.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Overall functioning
Measured with the Outcome Questionnaire - 45 (OQ-45). The OQ-45 consists of 45 items. Scores range from 0-180. Higher scores indicate higher symptom severity.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Self-compassion
Measured with the Self Compassion Scale - Short form (SCS-SF). The scale consists of six subscales each containing 2 items: self-kindness, self-judgment, common humanity, isolation, mindfulness and over-identification. The negatively phrased items will be reversed-scored before calculating subscale and total scores. Each subscale ranges from 2-14. A higher score indicates a higher level (better outcome) of self-kindness, common humanity, mindfulness, self-judgment, isolation, and over-identification. Total scores range from 12 to 84 (summed subscale scores), a higher score indicates a higher level of self-compassion.
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Influence of Pavlovian information on goal-directed behaviour
Measured with the Pavlovian to Instrumental Transfer (PIT) task
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)
Working memory - emotion-dependent update and ignore capacity of working memory
Measured with the Working Memory Update/Ignore Emotion Task (WMUIET)
Time frame: Change from baseline to mid-treatment (4 weeks), to post-treatment (8 weeks)