Mindfulness-based stress reduction and health benefits: A meta-analysis

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Abstract

Objective

Mindfulness-based stress reduction (MBSR) is a structured group program that employs mindfulness meditation to alleviate suffering associated with physical, psychosomatic and psychiatric disorders. The program, nonreligious and nonesoteric, is based upon a systematic procedure to develop enhanced awareness of moment-to-moment experience of perceptible mental processes. The approach assumes that greater awareness will provide more veridical perception, reduce negative affect and improve vitality and coping. In the last two decades, a number of research reports appeared that seem to support many of these claims. We performed a comprehensive review and meta-analysis of published and unpublished studies of health-related studies related to MBSR.

Methods

Sixty-four empirical studies were found, but only 20 reports met criteria of acceptable quality or relevance to be included in the meta-analysis. Reports were excluded due to (1) insufficient information about interventions, (2) poor quantitative health evaluation, (3) inadequate statistical analysis, (4) mindfulness not being the central component of intervention, or (5) the setting of intervention or sample composition deviating too widely from the health-related MBSR program. Acceptable studies covered a wide spectrum of clinical populations (e.g., pain, cancer, heart disease, depression, and anxiety), as well as stressed nonclinical groups. Both controlled and observational investigations were included. Standardized measures of physical and mental well-being constituted the dependent variables of the analysis.

Results

Overall, both controlled and uncontrolled studies showed similar effect sizes of approximately 0.5 (P<.0001) with homogeneity of distribution.

Conclusion

Although derived from a relatively small number of studies, these results suggest that MBSR may help a broad range of individuals to cope with their clinical and nonclinical problems.

Introduction

Coping with the symptoms, disability, and uncertain perspectives of chronic disease is a harrowing challenge for a significant proportion of the population. However, addressing the biopsychosocial adjustment of chronically ill individuals is an area that continues to tax the resources and limits of modern conventional medicine and one for which few professionals have adequate time or training. Programs that do exist to improve the well-being and health status of the chronically ill are often still in their infancy and typically directed toward a specific illness and limited range of symptoms. A single, relatively brief and cost-effective program that can potentially be applied to a range of chronic illnesses and is able to effect a positive shift in fundamental perspectives toward health and disease should be of great interest.

During the last two decades, a group-intervention program known as mindfulness-based stress reduction (MBSR) has been proposed as just such an approach [1]. This procedure has been employed among patients with a wide variety of chronic clinical ailments, as well among groups of relatively healthy individuals who have hoped to improve their abilities to cope with the normal but often significant stresses of daily life. Preliminary reports have suggested substantial benefits for individuals suffering from chronic pain, fibromyalgia, cancer, anxiety disorders, depression and the stresses of contexts as diverse as medical school and prison life (e.g., [2*], [3], [4*]). However, many of the published studies remain critically unevaluated and may be of questionable scientific rigor or too limited in scope to confirm such claims. A recently published paper provided a valuable critique of mindfulness studies, but without providing a quantitative assessment of existing studies [5].

In this report, we provide a meta-analytic review of all accessible published and unpublished investigations purporting health-related benefits of MBSR. Our aim is to provide an empirical basis for evaluating whether or not evidence exists that MBSR systematically improves health-related dimensions among the chronically ill and others, what and how large the specific benefits may be, and whether more extensive evaluation of MBSR may be warranted.

MBSR is a group program that focuses upon the progressive acquisition of mindful awareness, or mindfulness. The construct of mindful awareness originated in earliest Buddhist documents but is neither religious nor esoteric in nature [6]. Several Buddhist treatises detail an elaborate psychological theory of mind, in which mindfulness consistently plays a central role [7]. Mindfulness is characterized by dispassionate, nonevaluative and sustained moment-to-moment awareness of perceptible mental states and processes. This includes continuous, immediate awareness of physical sensations, perceptions, affective states, thoughts, and imagery. Mindfulness is nondeliberative: It merely implies sustained paying attention to ongoing mental content without thinking about, comparing or in other ways evaluating the ongoing mental phenomena that arise during periods of practice. Thus, mindfulness may be seen as a form of naturalistic observation, or participant-observation, in which the objects of observation are the perceptible mental phenomena that normally arise during waking consciousness. Underlying this concept and approach are the following assumptions: (1) Humans are ordinarily largely unaware of their moment-to-moment experience, often operating in an “automatic pilot” mode; (2) we are capable of developing the ability to sustain attention to mental content; (3) development of this ability is gradual, progressive and requires regular practice; (4) moment-to-moment awareness of experience will provide a richer and more vital sense of life, inasmuch as experience becomes more vivid and active mindful participation replaces unconscious reactiveness; (5) such persistent, nonevaluative observation of mental content will gradually give rise to greater veridicality of perceptions; and (6) because more accurate perception of one's own mental responses to external and internal stimuli is achieved, additional information is gathered that will enhance effective action in the world, and lead to a greater sense of control (e.g., [1], [6], [7]).

Health-related benefits derived from such claims should include enhanced emotional processing and coping regarding the effects of chronic illness and stress, improved self-efficacy and control, and a more differentiated picture of wellness in which stress and ailments play natural roles but still allow enjoyment of life as full and rich (i.e., improved quality of life including general competencies, and affective and social dimensions). Evidence from the following meta-analysis may bear upon confirming or refuting such claims.

MBSR is a structured 8–10 week, group program with groups usually varying between 10 and 40 participants. Groups may be either heterogeneous or homogeneous with respect to disorders or problem areas of participants. Single weekly sessions are typically 2.5 h, and there is an additional single all-day session per course on a weekend day. Each session covers particular exercises and topics that are examined within the context of mindfulness. These include different forms of mindfulness meditation practice, mindful awareness during yoga postures, and mindfulness during stressful situations and social interactions. Because development of mindfulness is predicated upon regular and repeated practice, participants enter upon enrolling into a commitment to carry out daily 45-min homework assignments primarily in the form of meditation practice, mindful yoga and applying mindfulness to situations in everyday life.

For the purpose of the current review, we examined 64 empirical reports that either used the structured MBSR program or applied mindfulness procedures as the central component of a group procedure to improve health-related measures.

Section snippets

Methods

Methods of the analysis and inclusion criteria were specified in advance and documented in a protocol.

Results

We retrieved 64 studies but only 20 reports, comprising a total of 1605 subjects, met the inclusion criteria (noted in References with an asterisk and in Further Readings; note that some studies were presented in more than one publication). A list of all retrieved studies are included in Appendix A. Most of the excluded studies did not operationalize mindfulness training in the specified manner or reported insufficient statistical details for effect size calculation.

Studies investigating

Discussion

Our findings suggest the usefulness of MBSR as an intervention for a broad range of chronic disorders and problems. In fact, the consistent and relatively strong level of effect sizes across very different types of sample indicates that mindfulness training might enhance general features of coping with distress and disability in everyday life, as well as under more extraordinary conditions of serious disorder or stress. Another recently published study employing different inclusion criteria and

Acknowledgements

This investigation was supported by grants to the first author from the YeTaDeL Foundation, (Cortaro, AZ, USA), and the Research and Training Institute of the Hebrew Rehabilitation Center for the Aged (Boston, MA, USA), and grants to the last two authors from the Samueli Institute (Corona del Mar, CA, USA). We would also like to thank the authors of the studies cited in this article for their help in responding to our inquiries and providing us with unpublished data. Finally we also wish to

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