Stress and Anxiety
Abstract & Commentary
Meditation Effectiveness for Stress-related Outcomes
By Nancy Selfridge, MD
Associate Professor, Chair, Department of Clinical Medicine, and Assistant Dean, Clinical Sciences, Ross University School of Medicine, Commonwealth of Dominica, West Indies
Dr. Selfridge reports no financial relationships relevant to the field of study.
Synopsis: A systematic review and meta-analysis of randomized controlled trials of meditation programs demonstrated moderate strength of evidence for mindfulness meditation for improving anxiety, depression, and pain.
Source: Goyal M, et al. Meditation programs for psychological stress and well-being: A systematic review and meta-analysis. JAMA Intern Med 2014;174:357-368.
In order to assess the strength of evidence for recommending meditation programs as effective interventions for stress-related health problems, the authors conducted a systematic review and meta-analysis of randomized clinical trials of meditation compared to an active control group. Longitudinal studies of adult subjects with medical or psychiatric stress-related diagnoses and a structured protocol-based meditation program with at least 4 hours of training were additional inclusion criteria. Both mantra-based (e.g., transcendental meditation) and mindfulness-based (e.g., mindfulness-based stress reduction) programs were included. Trials had to include an active control group matched in time and attention to the intervention group. Forty-seven trials with 3515 participants resulted from this literature review process. Effects of meditation on several outcomes were evaluated: negative affect (anxiety, depression), positive affect (sense of well-being), health-related quality of life, attention, pain, weight, and stress-related behaviors impacting on health (substance use, sleep). Trials were evaluated for intervention fidelity, including quantity of structured training, home practice recommended, instructor qualifications, and descriptions or measures of participant adherence.
To display and compare outcome data from these trials, the authors calculated the relative difference in change scores, computed by taking the change from baseline in the treatment group, subtracting the change from baseline in the control group and dividing by the baseline score in the treatment group. This calculation allowed an estimate of the direction and magnitude of effect for all studies.
Control groups were classified as nonspecific active or specific active. Nonspecific active control groups — e.g., educational training — consisted of programs that matched the meditation intervention in terms of time and contact but did not represent a known intervention for the problem, allowing control for the nonspecific effects of time, attention, and participant expectations and more accurate measures of the efficacy of meditation. Specific active controls — e.g., drugs, exercise, and other behavioral therapies — allowed for comparisons of meditation with interventions known or expected to improve clinical outcomes.
Authors further assessed the included trials for strength of evidence using grading schemas and tools primarily from Methods Guide for Conducting Comparative Effectiveness Reviews, a publication of the Agency for Healthcare Research and Quality, supplemented with tools from the Cochrane Collaboration to assess risk of bias. Strength of evidence was stratified into four categories: high (high confidence that the evidence reflects the true effect; further studies are unlikely to change this confidence), moderate (moderate confidence that the evidence reflects the true effect; further studies may change this confidence), low (low confidence that the evidence reflects the true effect and further research is likely to change both confidence in the effect and the estimate of effect), and insufficient (evidence unavailable or inadequate for a conclusion).
Mindfulness meditation programs demonstrated moderate strength of evidence for improving anxiety (effect size 0.38 [95% CI, 0.12-0.64] at 8 weeks and 0.22 [95% CI, 0.02-0.43] at 3-6 months), depression (0.30 [95% CI, 0.00-0.59] at 8 weeks and 0.23 [95% CI, 0.05-0.42] at 3-6 months), and pain (0.33 [0.03-0.62]). Low strength of evidence was noted for improving stress/distress and mental health-related quality of life. Mantra-based meditation programs demonstrated low or no effect on multiple outcomes or insufficient evidence existed to make a judgment. Meditation programs appeared no better or worse than any active intervention in the specific active control trials. Though the meditation interventions were divided into mindfulness-based and mantra-based in the analysis, no sub-analyses were performed grouping types of active control interventions. The authors stated that there were no reported adverse effects in any of the trials chosen for review and analysis. They did not comment on any contraindications based on baseline mental health or risk of psychosis.
A previous summary of mindfulness research reported evidence that mindfulness training reduces negative emotion and perceived stress.1 The body of research on meditation, however, includes observational studies, controlled trials using passive control strategies such as "wait-listing" that does not control for time, attention and expectation, and studies of inadequate sample size. The greatest value of this systematic review and analysis by Goyal et al is the inclusion of only randomized trials with active controls and their rigorous attempt to grade the strength of evidence in these selected trials, a process necessary to create the data needed to support clinical guidelines. Calculating and comparing standardized mean differences in effect sizes between studies with diverse outcome measures was an additional strength of this review.
Nonetheless, evaluating meditation research is fraught with challenges. Protocol interventions vary in format and duration. Trainer criteria, in terms of experience with meditation and/or teaching, are not specified or are not reported at all, though intuitively the experience and expertise of the teacher should have some impact on the student and outcomes. The authors cite four main biases in the relatively high-quality studies they chose for review: lack of blinding of outcomes, lack of allocation concealment, lack of intention-to-treat analysis of data, and high attrition of participants. Though brain functional changes associated with positive affect have been reported after just 8 weeks of mindfulness-based stress reduction training consisting of approximately 27 hours of direct instruction, the effective dose of a meditation intervention for optimum treatment of stress-related health problems is unknown.2 Several studies over the last decade studying brain changes in meditating monks suggest that neural effects of meditation noted on fMRI certainly increase with time and meditation experience. Most meditation trials are of very short duration. More time with expert training and dedication to practice might result in a level of skill and mastery that would demonstrate an even larger effect size on these studied outcomes than recent trials suggest. Rigorously constructed and implemented randomized, active, controlled trials of longer duration are necessary to resolve remaining questions and concerns about the efficacy and comparative effectiveness of meditation as an intervention.
More than 3 decades of research support mindfulness-based meditation as a health-promoting and potentially therapeutic intervention. This study graces us with an analysis of some of the best of this research for medical decision-making.
This review affirmed that no adverse effects of meditation were reported in any of these randomized, controlled trials. With this review and analysis as support, clinicians can confidently discuss with patients the potential effectiveness and safety of meditation as an intervention or adjunctive therapy for anxiety, depression, and pain, and state that it appears to work as well as other intervention programs shown or believed to be effective. Choosing between interventions will boil down to the personal preference of the patient as part of shared decision-making processes until further research suggests a clear advantage of meditation practices for these problems.
1. Greeson J. Mindfulness research update: 2008. Complement Health Pract Rev 2009;14:10-18.
2. Davidson RJ, et al. Alterations in brain and immune function produced by mindfulness meditation. Psychosom Med 2003;65:564-570.