Mindfulness - Application to diverse populations and working mechanisms

Chapter 1: General Introduction. The research described in this thesis is driven by two overall aims: [1] to investigate if mindfulness is a feasible and effective approach to relief different kinds of mental suffering as encountered in different contexts and settings such as social welfare centers (Chapter 2), schools (Chapter 3 and 4) and pediatric oncology units (Chapter 5); and [2] to investigate its working mechanisms across different study populations such as adolescents (Chapter 4 and 5) and adults (Chapter 2 and 6). Chapter 2: A Mindfulness-Based Intervention for economically disadvantaged people: Effects on symptoms of stress, anxiety and depression, and on cognitive reactivity and overgeneralization. The chronic exposure to stress of living with less money than one needs affects people's well-being. This study shows that a mindfulness-based intervention (MBI) significantly reduced symptoms of stress, anxiety and depression, cognitive reactivity and overgeneralization (both cognitive vulnerability factors for depression), and significantly improved mindfulness skills. These findings provide promising evidence of the effectiveness of MBIs to promote economically disadvantaged people’s mental well-being and show that a MBI is feasible in social welfare centers. Chapter 3: Potential Moderators of the Effects of a School-Based Mindfulness Program on Symptoms of Depression in Adolescents. A large randomized controlled trial delivering mindfulness or no treatment was conducted in secondary schools in Flanders. The mindfulness program was found to be effective in reducing symptoms of depression post-intervention and at six months follow-up. No moderation effects were found of gender, age, and school-track meaning that the training might work equally well for girls and boys, for younger and older students, and across school-tracks. The potential impact of mindfulness on curative as well as preventive aspects is discussed. Chapter 4: Processes of change in a school-based mindfulness program: cognitive reactivity and self-coldness as mediators. A moderated time-lagged mediation model was used to test the mediation of training effect in the randomized controlled trial data conducted in schools from Chapter 3. Post-treatment changes in cognitive reactivity and self-coldness, an aspect of self-compassion, mediated subsequent changes in symptoms of depression, anxiety and stress. The transdiagnostic nature of the intervention is discussed. Chapter 5: A Mindfulness-Based Intervention for adolescents and young adults after cancer treatment: Effects on quality of life, emotional distress, and cognitive vulnerability. The potential efficacy of a mindfulness based intervention to alleviate emotional distress and improve quality of life in adolescent and young adult cancer survivors was studied. Multilevel modelling showed 1) a significant reduction in emotional distress and improvement in quality of life at 3 months follow-up, 2) a significant reduction in negative attitudes toward self (i.e. a cognitive vulnerability factor for emotional distress, in particular depression) and 3) a significant improvement in mindfulness skills. Chapter 6: An Experience Sampling Study Examining the Potential Impact of a Mindfulness-Based Intervention on Emotion Differentiation. In this study we hypothesize, and study empirically, whether MBI may impact the differentiation of negative and positive emotions, an essential skill for adaptive emotion regulation. Multilevel modeling showed a significant improvement in negative emotion differentiation post-intervention and at four months of follow-up, and a significant improvement in positive emotion differentiation at four months follow-up. A time-lagged mediation model showed that post-treatment changes in mindfulness skills mediated subsequent changes in negative emotion differentiation. These results suggest that MBI is a promising approach to improve people’s emotion differentiation skills. Chapter 7: General Discussion. A summary and synthesis of the results is given in relation to the most recent findings in mindfulness research. Strengths and limitations are discussed and indications for future research are presented.status: publishe