Mindfulness in Couples

Evaluating a Mindfulness-Based Couple Intervention (MBCI): A Randomized Feasibility Trial With Progression to Full-scale Trial

Considering the high prevalence of couple distress in Western countries and rising divorce rates, there is a pressing need for accessible and evidence-supported interventions that can strengthen relationship functioning. Although mindfulness has been positively linked to relationship functioning, only few studies have investigated the effects of mindfulness interventions specifically targeted at couples. However, these studies suffer from methodological limitations such as lack of an active control group.

To address this gap, a feasibility trial with progression to a full-scale randomized controlled trial (RCT) will be conducted, depending on whether stoppage criteria are met, to evaluate the effectiveness of a Mindfulness-Based Couple Intervention (MBCI) compared to an online active control intervention (Self-expansion Intervention) and waitlist control group. Moreover, consolidation of intervention effects is examined up to 6 months post-intervention. Finally, possible working mechanisms and the effect of potential moderators are examined.

The current study has three arms: (i) MBCI, (ii) active control intervention (i.e., a self-expansion program) and (iii) waitlist control, with assessments at baseline (T0), immediately post-intervention (T1) and at 6 months post-intervention (T2). After the follow-up assessments, waitlisted participants are offered to take part in (an online version of) either the MBCI or the active control intervention.

The study aims to include 213 couples (426 participants, age >20 years) with a minimum relationship duration of 2 years. Couples will be randomly assigned with a 3:3:2 ratio to MBCI, Self-expansion or waitlist, respectively (with a total of 80 couples in the intervention groups and 53 couples in the waitlist control group). This is a multi-site RCT, with five different centers spread across the Netherlands, based in Nijmegen, Tilburg, Amsterdam, Maastricht and Groningen. In the feasibility phase, 42 eligible couples will be recruited from two sites (Nijmegen and Tilburg). Stratified variable block randomization will be used(block sizes of 8 and 16), with study site as stratification factor.

The MBCI is a close adaptation of the widely used and well-researched Mindfulness-Based Stress Reduction program (MBSR), developed by our research team. Couples learn how to practice mindfulness meditation and how to apply mindfulness in their daily life and in their relationship. As compared to the MBSR, it includes adapted and additional exercises to practice mindfulness within the relationships, such as mindful communication exercises, mindful touch, and mindfully viewing one's partner. The active control intervention encourages couples to invest in self-expansion, by doing a novel activity together every week. This intervention is based on self-expansion theory. According to this theory, couples are satisfied with their relationship as long as they experience a sense of self-expansion. A sense of self-expansion can be promoted by engaging in novel activities together and gaining new insights from each other. Both the mindfulness- and self-expansion interventions consist of 8 weekly sessions, plus a silent day (for MBCI) or a day out (for the self-expansion intervention). Interventions are similar in non-specific factors such as format, structure, time commitment, teacher support, and group dynamics.

The primary outcome is to compare self-reported relationship satisfaction as measured by the Couple Satisfaction Index (CSI-4) from pre-intervention (T0) to immediately post-intervention (T1) between the MBCI group compared to the active control group and between the MBCI group compared to the waitlist control group. Secondary outcomes include the difference in relationship satisfaction from pre-intervention (T0) to 6 month post-intervention (T2) between participants in the MBCI compared to the active and waitlist control group, as well as differences between participants in the MBCI compared to the active and waitlist control group in various relationship behaviors, perceptions of the partner, and individual outcomes measured from pre-intervention (T0) to immediately post-intervention (T1) and pre-intervention (T0) to 6 months post-intervention (T2). In addition, a number of potential moderators, including commitment, attachment style and trait mindfulness measured at T0 will be assessed to determine for whom these programs work.

Unless the trial team determines, based on stoppage criteria, that trial procedures need important modifications thereby re-setting the full-scale trial as a new trial, the outcome data of the participants in the feasibility portion will be utilized in the analyses of the full-scale trial.

Study Overview

• Status: Recruiting
• Conditions: Romantic Relationship Functioning
• Intervention / Treatment: Behavioral: MBCI; Behavioral: SE training

Detailed Description

Background and objectives

A satisfying romantic relationship strongly predicts mental and physical health, supporting emotion regulation, life satisfaction, and healthy lifestyles. In contrast, chronic relationship distress is linked to anxiety, depression, stress, and negative effects on work and children's wellbeing. Given its high prevalence and rising divorce rates in Western countries, accessible, evidence-based interventions are needed.

Mindfulness is associated with improved relationship outcomes (e.g., satisfaction, acceptance, closeness), but research is limited by methodological weaknesses and a lack of insight into underlying mechanisms. Although mindfulness-based interventions are effective for individual symptoms like depression, anxiety, and stress, few studies have examined their effects in couples.

To address this gap, a feasibility trial with progression to a full-scale randomized controlled trial (RCT) will be conducted, depending on whether stoppage criteria are met, to evaluate the effectiveness of a Mindfulness-Based Couple Intervention (MBCI) to enhance relationship satisfaction compared to an active control intervention (i.e., self-expansion intervention) and waitlist control group. Furthermore, outcomes will be assessed at 6 months post-intervention and investigate possible working mechanisms and potential moderators.

Outcome measures described below will all be measured with questionnaires. Notably, the trial also involves additional methodologies, such as a computer-based task, Experience Sampling Methodology (ESM), and a conflict study utilizing physiological measures and behavioral observations. These will not be described further in the current registered report, as they are intended to elucidate the working mechanisms of the interventions rather than to evaluate the general effectiveness of the MBCI. All of these additional sub-studies will be preregistered prior to data analysis.

Recruitment

This is a large-scale multi-site RCT, with five different centers spread across the Netherlands, based in Nijmegen, Tilburg, Amsterdam, Maastricht and Groningen. The study aims to include a total of 213 couples (426 participants, >20 years) with a minimum relationship duration of 2 years. In the feasibility phase of the study, 42 eligible couples will be recruited from two sites (Nijmegen and Tilburg). Participants will be recruited via social media, flyers in public spaces, adds in local newspapers and magazines and through our own network. Interested couples can send their contact details via a Qualtrics form, after which they will be contacted to schedule a screening interview and send a short pre-screening questionnaire on intimate partner violence (which is an exclusion criterium). In the screening interview, participants will be given more information about the study and the interventions and assess eligibility. If couples are eligible and willing to participate, they will be sent the information letter and informed consent form.

Progression from feasibility to full-scale trial

In the feasibility phase of the proposed study, the trial team will collect data to improve several aspects of the trial's processes. At the completion of the feasibility portion, the trial team plans to proceed directly to the full-scale trial, including results from the feasibility stage in the full-scale trial, unless one or more of the stoppage criteria are met. In that case, the trial team will address issues that are identified and begin the full-scale trial anew, separate from the feasibility trial.

The stoppage criteria are the following:

Recruitment and enrolment of trial participants: If the study fails to enroll sufficient eligible participants to fill the three arms within the two months prior to start of the intervention programs. The study will need at least 15 couples (30 participants) at each location (i.e., Tilburg and Nijmegen) in order to have a minimum of five couples in every intervention group, which is an acceptable group size to deliver the interventions to. The trial team will discuss whether it is feasible and sufficiently productive to improve the recruitment strategy and if so, adapt the recruitment strategy accordingly and progress to the full-scale trial. If not, the trial team will consider eliminating the active control intervention (i.e., proceeding with a two-arm trial) and progress to the full-scale trial without data from participants assigned to the active control intervention.

Fidelity of the delivery of the intervention: All sessions of both interventions will be recorded, such that only the teacher is visible. Per location (i.e., Tilburg and Nijmegen), recordings of two sessions of each intervention (25%) will be randomly picked for evaluation. For the MBCI, the MBI-TAC will be used and an additional adherence checklist specifically developed to assess the relationship-related and adapted components of the intervention. For the self-expansion intervention, an adherence checklist will be developed. Two researchers will independently assess if the components of the sessions were delivered according to the pre-specified programs. If more than 20% of the components are not delivered as specified. The trial team will seek to identify barriers to the delivery of the intervention, and modify how teachers are trained prior to delivering the interventions or the interventions themselves accordingly, before proceeding to the full-scale trial. After completion of the data collection, a sensitivity analysis will be conducted to evaluate the influence of including feasibility data in our final analyses.

Intervention drop-out: If more than 20 percent of participants assigned to the MBCI or active control program drop out of the intervention. Drop-out is defined as completing less than five sessions (including the full-day session). The trial team will investigate to identify reasons why participants drop out and will discuss if the intervention needs to be modified accordingly, before proceeding to the full-scale trial. In case the intervention needs to be substantially modified, the full-scale trial would need to commence as a new trial.

Measurement drop-out: If more than 20 percent of the post-intervention measurements of the primary outcome of the study are missing. Additionally, missing data on all other outcome measures will be kept track of (although these are not stoppage criteria). The trial team will investigate to identify reasons why participants drop out of the measurement(s) or why there is missing data and will modify or eliminate the particular measurement(s) accordingly, before proceeding to the full-scale trial. The trail team will need to commence anew with adapted measurement(s) in the full-scale trial or exclude the measurement(s) from the full-scale trial in case it needs to be eliminated.

At the end of the feasibility trial, the investigators will use the collected information and evaluation of the stoppage criteria to decide whether to: (1) Continue to the full-scale RCT without modifications to the trial procedures, (2) Modify trial procedures based on participant and teacher feedback before continuing to the full-scale trial, or (3) Modify the trial procedures before re-setting them and conducting the full-scale RCT as a new trial (in this case, outcome data collected during the feasibility phase will not be included in the analyses of the full-scale trial).

Randomization

After baseline assessment, couples will be randomly assigned with a 3:3:2 ratio to one of three groups (with a total of 80 couples in the intervention groups and 53 couples in the waitlist control group). The research team will use block randomization with block sizes of 8 and 16 and stratified by site. Randomization will be done in Castor EDC, which has full randomization concealment.

Interventions

The RCT includes three arms: treatment, active control and waitlist control. Waitlisted participants are offered the option to follow an online version of either the MBCI or the active control intervention after completion of the follow-up measurements. In the RCT, both the MBCI and self-expansion intervention consist of eight weekly group sessions and are designed to be comparable in non-specific factors such as structure, time commitment, teacher support, group dynamics, and expectations. Both interventions were designed by our research team and were modified according to feedback from couples taking part in a pilot of the intervention, (for preregistration of the pilot see: https://osf.io/3c4a6/overview?view_only=6e19f4a6303f426fa3229a508546c999 ).

Outcome measures

Outcome assessment for the trial will occur at baseline (T0), immediately post-intervention (T1) and 6 months post-intervention (T2). The primary outcome is the difference in self-reported relationship satisfaction as measured by the Couple Satisfaction Index (CSI-4) between participants in the MBCI compared to the active and waitlist control group from pre-intervention (T0) to immediately post-intervention (T1). Secondary outcomes include the difference in relationship satisfaction from pre-intervention (T0) to 6 months post intervention (T2) between participants in the MBCI compared to the active and waitlist control group, as well as the difference between participants in the MBCI compared to the active and waitlist control group in various relationship behaviors, perceptions of the partner, and intrapersonal outcomes measured at from pre-intervention (T0) to immediately post-intervention (T1) and from pre-intervention (T0) to 6 months post-intervention (T2). In addition, a number of potential moderators will be assessed to determine for whom these programs work best. Notably, the trial also involves additional methodologies, such as a computer-based reaction time task, Experience Sampling Methodology (ESM) and a conflict study utilizing physiological measures and behavioral observations. These will not be described further in the current registered report, as they are intended to elucidate the working mechanisms of the interventions rather than to evaluate the general effectiveness of the MBCI. All of these additional sub-studies will be preregistered prior to data analysis.

Data analysis

Consistent with the feasibility trial design and small sample size, no hypothesis tests are planned for the feasibility portion of the trial. Instead, the investigators will present a description of the feasibility elements, including recruitment and eligibility of the participants, and numbers and percentages of participants who completed the intervention and responded to the different measures.

Only the main statistical analyses will be described below. A more detailed statistical analyses plan will be uploaded before analyzing the data. In the full-scale trial, primary analyses will be run in an intent-to-treat sample. Two linear mixed-effects models will be run to assess differences in treatment effects from pre-intervention to immediately post-intervention to 6 months post-intervention, using the lmer function in lme4. One model will estimate the difference between MBCI and the waitlist control group, and the other between MBCI and the active control group. Random intercepts and random slopes will be included for couples and random intercepts for individuals within a couple. The timepoints will be entered as categorical variables, and estimated marginal means will be used to assess group differences at each time point, specifically to determine whether any treatment effects emerging between pre-intervention and immediately post-intervention are maintained or further enhanced at the 6 months post-intervention measurement. By using time as a categorical variable, no assumptions will need to be made on whether to expect the hypothesized linear effect from pre- to post-intervention to continue or to stabilize at 6 months post-intervention. The primary analysis would concern the fixed effect of the time x condition interactions from pre- to immediately post-intervention (MBCI compared to waitlist and MBCI compared to control). Stratification variable (i.e., 'site') will be added as a covariate. Effect sizes will be reported as standardized mean differences (Cohen's d) with 95% confidence intervals (CIs). Similarly, for secondary outcome measures a linear mixed-effects model will be employed, using the lmer function in lme4 to estimate differences in treatment effects from pre-intervention to immediately post-intervention to 6 months post intervention between MBCI and active control, and separately between MBCI and waitlist control, with time as a categorical variable. The investigators will not adjust for multiple analyses since a single primary outcome was identified a priori. All outcome analyses will be conducted in R. All analyses will be 2-sided with alpha = 0.05.

Mediation and moderation

To examine potential mechanisms underlying intervention effects on relationship satisfaction, additional mediation analyses will be conducted focusing on psychological processes theorized to be specifically targeted by the mindfulness intervention. The following mediators will be examined: changes in rumination, emotion regulation, stress trait mindfulness, and self-expansion. To examine whether intervention effects differ as a function of individual and relationship differences, moderation analyses will be conducted using pre-intervention measures of commitment, attachment style and trait mindfulness. Each moderator will be added separately to the primary analysis. The primary test of moderation will be the three-way interaction between time, treatment and moderator, indicating whether changes in relationship satisfaction differ between intervention conditions as a function of the moderator. These mediation and moderation analyses are considered secondary and exploratory, and results will be interpreted cautiously with respect to multiple comparisons.

• Study Type: Interventional
• Enrollment (Estimated): 426
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Johan C.T.M. Karremans, Prof. PhD; Phone Number: +31616805575; Email: johan.karremans@ru.nl
• Study Contact Backup: Name: Linda Kwakkenbos, PhD; Phone Number: +31641450052; Email: linda.kwakkenbos@ru.nl

Study Locations

• Netherlands
  • Gelderland
    • Nijmegen, Gelderland, Netherlands, 6525GD
      • Recruiting
      • Behavioral Science Institute, Radboud University
      • Contact: Johan C.T.M. Karremans, Prof. PhD; Phone Number: +31616805575; Email: johan.karremans@ru.nl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• age >20 years
• relationship duration of >2 years

Exclusion Criteria:

• One or both partners have followed an MBSR- or MBCT training or similar mindfulness program for at least four sessions in the past three years.
• One or both partners are currently in relationship therapy.
• One or both partners are unable to sufficiently speak and understand the Dutch language.
• Presence of severe mental disorders in one or both partners, namely addiction, suicidality (in the past 12 months) or psychosis (in the past 12 months?).
• Presence of partner violence (in the last 12 months)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Mindfulness-Based Couple Intervention; The Mindfulness-based Couple Intervention (MBCI) was designed by our research team. It consists of 8 weekly group sessions lasting 2,5 hours, delivered by a certified mindfulness trainer. It is a close adaptation of the widely-used and well-researched Mindfulness-Based Stress Reduction program (MBSR), following the same structure and topics. It teaches participants mindfulness meditation practice and how to apply mindfulness in their daily life and relationship. The sessions include group discussions, psycho-education, mediation practices and exercises done in couples, such as mindful communication exercises and mindful touch exercises. The intervention also involves weekly homework assignments, on which participants are expected to spend around 30-45 minutes per day. It also involves a 6 hour silent meditation retreat.	Behavioral: MBCI; Mindfulness-based Couple Intervention (MBCI)
Active Comparator: Self-expansion training; The self-expansion training was designed by our research team based on the Self-expansion theory. Self-expansion theory states that couples enrich each other's lives by doing novel activities together and gaining new insights from each other, which is beneficial to the relationship. The self-expansion training encourages partners to engage in novel, exciting activities that promote shared growth and is inspired by earlier self-expansion studies in which participants choose novel, exciting activities from a list. In our intervention, couples are asked to choose and complete a new activity aligned with a specific theme (e.g., physical exercise or creativity) every week, on which they spend approximately 2 hours or longer. During the sessions, participants share their experiences of the activities they have done. Sessions last 1 hour and 15 minutes and are delivered online (because of feasibility reasons). It includes an additional day out of approximately 6 hours.	Behavioral: SE training; Self-expansion training
No Intervention: Waitlist control; Participants in the waitlist control group do not follow an intervention for the duration of the study. After having completed the measurements, they have the option to follow an online version of one of the two interventions for free.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in Couple Satisfaction Index-4 scores between participants in the MBCI arm and waitlist control, between participants in the SE arm and waitlist control, and between participants in the MBCI arm and SE arm immediately post-intervention	The Couple Satisfaction Index (4 items, CSI-4) measures relationship satisfaction, a global assessment of contentment in the romantic relationship. The first item is measured on a 7-point Likert scale (0=extremely unhappy, 6=perfect), the other items on a 5-point Likert scale (0=not at all, 5=completely). Maximum score =22. Higher scores indicate higher satisfaction.	Time Frame: 1 week post-intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in Couple Satisfaction Index-4 scores between participants in the MBCI arm and waitlist control, between participants in the SE arm and waitlist control, and between participants in the MBCI arm and SE arm immediately post-intervention	The Couple Satisfaction Index (4 items, CSI-4) measures relationship satisfaction, a global assessment of contentment in the romantic relationship. The first item is measured on a 7-point Likert scale (0=extremely unhappy, 6=perfect), the other items on a 5-point Likert scale (0=not at all, 5=completely). Maximum score =22. Higher scores indicate higher satisfaction.	6 months post-intervention
Relationship distress: Multidimension Stress Questionnaire for couples (MSF-P)	Relationship distress indicates subjective strain in the relationship because of stressors arising within the relationship. It is measured by the Multidimension Stress Questionnaire for couples (MSF-P) internal stress dimension, which consists of 10 items scored on a 4 point Likert scale (1=not at all, 4= strong). Higher scores indicate higher relationship distress. Maximum score = 40.	1 week post-intervention and 6 months post-intervention
Emotional intimacy: Perceived Relationship Quality Component scale (PRQC)	Emotional intimacy involves the perceived closeness, sharing of feelings, and emotional bonding with the partner. It is measured by the intimacy dimension of the Perceived Relationship Quality Component scale (PRQC) and consists of 3 items measured on a 7 point Likert scale (1 = not at all; 7 = extremely). Higher scores indicate higher emotional intimacy. Maximum score = 21.	1 week post-intervention and 6 months post-intervention
Perceived Partner Responsiveness: Perceived Responsiveness and Insensitivity scale (PRI)	Perceived partner responsiveness is the perception that the partner understands, validates, and cares about one's core needs during disclosure - reflecting attentiveness and emotional responsiveness. It is measured by the Perceived Responsiveness and Insensitivity scale (PRI), which consists of 8 items scored on a 6-point Likert scale (0= not at all; 5= completely). Maximum score = 40.	1 week post-intervention and 6 months post-intervention
Capitalization: Perceived Responses to Capitalization Attempts scale (PRCA)	Capitalization entails how one responds when a partner shares a positive event - especially with enthusiastic, active-constructive support that sustains relational satisfaction. It is measured by the Perceived Responses to Capitalization Attempts scale (PRCA), which consists of 4 items rated on a 5 point Likert scale (1= not at all true; 5= very true). A composite score is created by taking the average of the three nonsupportive responses (item 2-4) and subtracting that average score from the active-constructive score (item1). Maximum score = 4.	1 week post-intervention and 6 months post-intervention
Appreciation: Appreciation in Relationships Scale (ARS)	Appreciation is the recognition and verbal or behavioral expression of gratitude and esteem directed towards a romantic partner. It is measured by the Appreciation in Relationships Scale (ARS) which consists of 6 items rated on a 7 point Likert scale (1=strongly disagree; 7= strongly agree). Higher scores indicate more appreciation. Maximum score = 42.	1 week post-intervention and 6 months post-intervention
Conflict behavior: Conflict Behavior Scale	Conflict behavior is here conceptualized as behaviors expressed during conflict, based on 4 horsemen of apocalypse as conceptualized by Gottman: Criticism, contempt, defensiveness, withdrawal. It is measured by a conflict behavior scale developed by our team, which consists of 18 items measured on a 7 point Likert scale. There are three dimensions: one general dimension of conflict (2 items, maximum score = 14), partner conflict behavior (8 items, Maximum score = 56) and actor conflict behavior (8 items, Maximum score = 56). Higher scores indicate worse conflict behaviors.	1 month post-intervention and 6 months post-intervention
Self-expansion: Self-Expansion scale	The 13-item self-expansion scale measures the level of self-expansion in the relationship. Items are scored on a 7 point Likert scale (1= not very much, 7= very much). Higher scores indicate higher levels of self-expansion. Maximum score = 91.	1 week post-intervention and 6 months post-intervention
Sexual satisfaction: New Sexual Satisfaction Scale (NSSS) short form	Sexual satisfaction can be defined as an individual's subjective evaluation of the quality and rewards of their sexual experiences. It is measured by the Sexual Satisfaction Scale (SSS), which consists of 4 questions rated on a 7-point Likert scale. Higher scores indicate higher sexual satisfaction. Maximum score = 28.	1 week post-intervention and 6 months post-intervention.
Trait Mindfulness: Five Facets of Mindfulness Questionnaire short form (FFMQ-sf)	Trait mindfulness is the dispositional level of mindfulness. It is measured on the Five Facets of Mindfulness Questionnaire short form (FFMQ-sf) of 15 items. It consists of five subscales: observing, describing, acting with awareness, non-judging of inner experience and non-reactivity to inner experience. Items are scored on a five-point rating scale (1 = rarely true, 5 = always true). Higher scores are indicative of someone who is more mindful in their everyday life. Maximum score = 75.	1 week post-intervention and 6 months post-intervention
Relationship Mindfulness: Mindfulness in Couple Relationship Scale (MCRS)	Relationship mindfulness refers to mindfulness applied relationally - being fully present, attentive, and non-judgmental during interactions with one's partner. It is measured by the Mindfulness in Couple Relationship Scale (MCRS) and consists of 31 items rated on a 7 point Likert scale (1= strongly disagree; 7= strongly agree). Higher scores indicate higher levels of relationship mindfulness. Maximum score = 217.	1 week post-intervention and 6 months post-intervention
Rumination: Perseverative Thinking Questionnaire (PTQ)	Rumination refers to a repetitive, negative, uncontrollable thinking style focused on perceived threats and negative experiences. It is measured by a selection of 5 items from the Perseverative Thinking Questionnaire (PTQ) with the highest factor loading (items number 1, 3, 6, 8, 11), which are scored on a 5 point Likert scale (0= never; 4= almost always). Higher scores indicate higher levels of rumination. Maximum score = 20.	1 week post-intervention and 6 months post-intervention
Emotion Regulation: Difficulties in Emotion Regulation Scale (DERS)	Emotion regulation is the ability of an individual to modulate an emotion or set of emotions. It is measured by the Difficulties in Emotion Regulation Scale (DERS), which consists of 16 items measured on a 5 point Likert scale. Higher scores indicate higher levels difficulty in emotion regulation. Maximum score = 80.	1 week post-intervention and 6 months post-intervention
Stress: Perceived Stress Scale (PSS-5)	Stress levels are measured with the Perceived Stress Scale (PSS-5), which consists of 5 items rated on a 5 point Likert scale (0= never, 4 =very often). Higher scores indicate higher experienced stress. Maximum score = 20.	1 week post-intervention and 6 months post-intervention
Explicit partner evaluations	Our scale of explicit partner evaluations measures positive, negative, ambivalent and indifferent evaluations of someone's partner. The scale consists of 8 items measured on a 7 point likert scale from 1 (not at all) to 7 (extremely/completely). There are four dimensions: positive evaluations (1 item, maximum score=7), negative evaluations (1 item, maximum score=7), ambivalent evaluations (3 items, maximum score=21) and indifference (3 items, maximum score=21), which are computed separately (there is no total score of all dimensions together). Higher scores indicate more positive/negative/indifferent/ambivalent evaluations.	1 week post-intervention and 6 months post-intervention

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pre measurement commitment as a moderator of the effect of MBCI on change in relationship satisfaction from pre to post and pre to follow up compared to active and waitlist control groups.	Commitment is the intention to maintain a romantic relationship over the long term. It is measured by the commitment level items from the Investment Model Scale (IMS) and consists of 7 items rated on an 8-point Likert scale (1= do not agree at all; 8= agree completely). Higher scores indicate higher commitment. Maximum score = 56.	Pre measurement in the month before start of the intervention.
Pre measurement attachment style as a moderator of the effect of MBCI on change in relationship satisfaction from pre to post and pre to follow up compared to active and waitlist control groups.	Attachment style is the characteristic way people relate to others in the context of intimate relationships, developed during childhood. Attachment style is typically measured on two dimensions: anxious (worry about partner's availability) and avoidant (discomfort with intimacy). It is measured by the Experiences in Close Relationships Scale short form revised (ECRS-sf) and consists of 12 items scored on a 7 point Likert scale (1 = strongly disagree, 7 = strongly agree). Higher scores indicate higher insecure attachment. 6 items assess attachment anxiety (maximum score=48) and 6 items assess attachment avoidance (maximum score = 48).	Pre measurement in the month before start of the intervention.
Expectancy of the training	Expectancy of the training is measured with the Credibility Expectancy Questionnaire (CEQ). The CEQ is adapted to be specific to relationship improvement. This measure is only administered to participants who are randomized tot he intervention. It consists of 5 items rated on a 10 point Likert scale (1= not at all; 10 = very much). It consists of a credibility subscale (4 items, maximum score = 40) and an expectancy subscale (1 item, maximum score =10).	After randomization, before start of the intervention.
Motivation	Motivation of taking part in the intervention is assessed with 2 items, one designed by our research team and one taken from Conradi et al. (2018). This measure is only administered to participants randomized to an intervention. Items are rated on a 5 point Likert scale (1= strongly disagree; 5= strongly agree). Higher scores indicate higher motivation. Maximum score = 10.	After randomization, before start of the intervention
Opinion on the intervention	7 items are used to assess participants opinion on the intervention, of which 5 are designed by the research team and 2 are based on Carson et al. (2007). It includes questions on how exciting, relaxing, pleasant, interesting and helpful the intervention was, as well as a question asking how seriously the participant took part in the training and to what extend partners have done activities which they found interesting and stimulating. This questionnaire is only administered to participants randomized to one of the interventions. Items are rated on a 100-mm visual analogue scale from "not at all" to "extremely". No total score is computed.	1 week post-intervention
Adverse effects	Adverse effects are defined as any negative effects of the training on the relationship. Adverse effects will be assessed with the following 2 items (developed by us) only in the participants who are randomized to one of the training conditions. "To what extent did the training have a negative influence on your relationship" (reported on a VAS from 0-100, higher scores mean worse outcomes); and with "Can you say something about this" (open ended question).	1 week post-intervention
Adherence at follow up	Adherence at follow up to meditation practices will be measured for participants of the MBCI (4 items) and to what extent participants of the self-expansion training continue to engage in doing novel activities together (developed by our research team, 2 items). No total scores are computed.	6 months post-intervention
Teacher support	These questions are only administered to participants who are randomized to one of the interventions and are developed by us. 4 items on a VAS scale (from 0-100), with higher scores indicating better outcomes (more support). Questions are developed by us.	1 week post-intervention
Group support	These questions are only administered to participants who are randomized to one of the interventions and are developed by us. 3 items on a VAS scale (from 0-100), with higher scores indicating better outcomes (more support). Questions are developed by us.	1 week post-intervention

Collaborators and Investigators

• Sponsor: Behavioural Science Institute
• Collaborators: Radboud University Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): March 3, 2026
• Primary Completion (Estimated): April 1, 2028
• Study Completion (Estimated): September 1, 2028

Study Registration Dates

• First Submitted: February 20, 2026
• First Submitted That Met QC Criteria: February 20, 2026
• First Posted (Actual): February 25, 2026

Study Record Updates

• Last Update Posted (Actual): April 27, 2026
• Last Update Submitted That Met QC Criteria: April 22, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Mindfulness; MBSR; Couple intervention; Relationship satisfaction; Romantic relationship; Self-expansion
• Other Study ID Numbers: ECSW-2025-134R1; 406.23.PPO.023 (Other Grant/Funding Number: NWO (Nederlandse Organisatie voor Wetenschappelijk Onderzoek))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Upon request
• IPD Sharing Time Frame: 12 months after the collection of the primary outcome
• IPD Sharing Access Criteria: Approval of proposed purpose for data access
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No