Meditation Programs for Psychological Stress and Well-Being
Definition of Meditation
The National Center for Complementary and Alternative Medicine defines meditation as a “mind-body” method. This category of complementary and alternative medicine includes interventions that employ a variety of techniques that facilitate the mind’s capacity to affect bodily function and symptoms. In meditation, a person learns to focus attention. Some forms of meditation instruct the student to become mindful of thoughts, feelings, and sensations, and to observe them in a nonjudgmental way. Many believe this practice evokes a state of greater calmness, physical relaxation, and psychological balance.1
Current Practice and Prevalence of Use
Many people use meditation to treat stress and stress-related conditions, as well as to promote general health.2,3 A national survey in 2008 found that the number of people meditating is increasing, with approximately 10 percent of the population having some experience with meditation.2 A number of hospitals and programs offer courses in meditation to patients seeking alternative or additional methods to relieve symptoms or to promote health.
Forms of Meditation
Meditation training programs vary in several ways, including the emphasis on religion or spirituality, the type of mental activity promoted, the nature and amount of training, the use of an instructor, and the qualifications of an instructor, which may all affect the level and nature of the meditative skills learned. Some meditative techniques are integrated into a broader alternative approach that includes dietary and/or movement therapies (e.g., Ayurveda or yoga).
Researchers have categorized meditative techniques as emphasizing “mindfulness,” “concentration,” and “automatic self-transcendence.” Popular techniques such as transcendental meditation (TM) emphasize the use of a mantra in such a way that one “transcends” to an effortless state where there is no focused attention. Other popular techniques, such as mindfulness-based stress reduction (MBSR), are classified as “mindfulness” and emphasize training in present-focused awareness. Uncertainty remains about the extent to which these distinctions actually influence psycho-social stress outcomes.
Psychological Stress and Well-Being
Researchers have postulated that meditation programs may affect a range of outcomes related to psychological stress and well-being. The research ranges from the rare examination of positive outcomes, such as increased well-being, to the more common approach of examining reductions in negative outcomes, such as anxiety or sleep disturbance. Some studies address symptoms related to the primary condition (e.g., pain in patients with low back pain or anxiety in patients with social phobia), whereas others address similar emotional symptoms in clinical groups of people who may or may not have clinically significant symptoms (e.g., anxiety or depression in individuals with cancer).
Evidence to Date
Reviews to date have demonstrated that both “mindfulness” and “mantra” meditation techniques reduce emotional symptoms (e.g., anxiety and depression, stress) and improve physical symptoms (e.g., pain) from a small to moderate degree.4-23 These reviews have largely included uncontrolled studies or studies that used control groups that did not receive additional treatment (i.e., usual care or wait list). In wait-list controlled studies, the control group receives usual care while “waiting” to receive the intervention at some time in the future, providing a usual-care control for the purposes of the study. Thus, it is unclear whether the apparently beneficial effects of meditation training are a result of the expectations for improvement that participants naturally form when obtaining this type of treatment. Additionally, many programs involve lengthy and sustained efforts on the part of participants and trainers, possibly yielding beneficial effects from the added attention, group participation, and support participants receive, as well as the suggestion that symptoms will likely improve with these increased efforts.24,25
The meditation literature has significant limitations related to inadequate control comparisons. An informative analogy is the use of placebos in pharmaceutical trials. The placebo is typically designed to match the “active intervention” in order to elicit the same expectations of benefit on the part of both provider and patient, but not contain the “active” ingredient. Additionally, placebo treatment includes all components of care received by the active group, including office visits and patient-provider interactions. These nonspecific factors are particularly important to control when the evaluation of outcome relies on patient reporting. In this situation, in which double-blinding has not been feasible, the challenge to execute studies that are not biased by these nonspecific factors is more pressing.25 Thus, there is a clear need to examine the specific effects of meditation in randomized controlled trials (RCTs) in which expectations for outcome and attentional support are controlled.
Clinical and Policy Relevance
There is much uncertainty regarding the differences and similarities between the effects of different types of meditation.26,27 Given the increasing use of meditation across a large number of conditions, it is important for patients, clinicians, and policymakers to understand the effects of meditation, types and duration of meditation, and settings and conditions for which meditation is efficacious. While some reviews have focused on RCTs, many, if not most, of the included studies involved wait-list or usual-care controls. Thus, there is a need to examine the specific effects of meditation interventions relative to conditions in which expectations for outcome and attentional support are controlled.
The objectives of this systematic review are to evaluate the effects of meditation programs on affect, attention, and health-related behaviors affected by stress, pain, and weight among people with a medical or psychiatric condition in RCTs with appropriate comparators.
Scope and Key Questions
This report reviews the efficacy of meditation programs on psychological stress and well-being among those with a clinical condition. “Affect” refers to emotion or mood. It can be positive, such as the feeling of well-being, or negative, such as anxiety, depression, or stress. Studies usually measure affect through self-reported questionnaires designed to gauge how much someone experiences a particular affect. “Attention” refers to the ability to maintain focus on particular stimuli; clinicians measure this directly. Studies measure substance use as the amount consumed or smoked over a period of time, and include alcohol consumption, cigarette smoking, and use of other drugs such as cocaine. They measure sleep as the amount of time spent asleep versus awake or as overall sleep quality. Studies measure sleep time through either polysomnography or actigraphy, and sleep quality through self-reported questionnaires. They measure eating using food diaries to calculate how much energy or fat a person has consumed over a particular period of time. They measure pain similarly to affect, by a self-reported questionnaire to assess how much pain an individual is experiencing. Studies measure pain severity on a numerical rating scale from 0 to 10 or by using other self-reported questionnaires. The studies measure weight in pounds or kilograms.
The Key Questions are as follows:
Key Question 1. What are the efficacy and harms of meditation programs on negative affect (e.g., anxiety, stress) and positive affect (e.g., well-being) among those with a clinical condition (medical or psychiatric)?
Key Question 2. What are the efficacy and harms of meditation programs on attention among those with a clinical condition (medical or psychiatric)?
Key Question 3. What are the efficacy and harms of meditation programs on health-related behaviors affected by stress, specifically substance use, sleep, and eating, among those with a clinical condition (medical or psychiatric)?
Key Question 4. What are the efficacy and harms of meditation programs on pain and weight among those with a clinical condition (medical or psychiatric)?
Figure A. Analytic framework for meditation programs conducted in clinical and psychiatric populations
Figure A illustrates our analytic framework for the systematic review. The figure indicates the populations of interest, the meditation programs, and the outcomes that we reviewed. This figure depicts the Key Questions (KQs) within the context of the population, intervention, comparator, outcomes, timing, and setting (PICOTS) framework described in Table A. Adverse events may occur at any point after the meditation program has begun.
KQ = Key Question
Literature Search Strategy
We searched the following databases for primary studies through November 2012: MEDLINE®, PsycINFO®, Embase®, PsycArticles, SCOPUS, CINAHL, AMED, and the Cochrane Library. We developed a search strategy for MEDLINE, accessed via PubMed®, based on medical subject headings (MeSH®) terms and text words of key articles that we identified a priori. We used a similar strategy in the other electronic sources. We reviewed the reference lists of included articles, relevant review articles, and related systematic reviews (n=20) to identify articles that the database searches might have missed. We did not impose any limits based on language or date of publication.
Two trained investigators independently screened articles at the title-and-abstract level and excluded them if both investigators agreed that the article met one or more of the exclusion criteria (Table A). We resolved differences between investigators regarding abstract eligibility through consensus.
Paired investigators conducted a second independent review of the full-text article for all citations that we promoted on the basis of title and abstract. We resolved differences regarding article inclusion through consensus.
Paired investigators conducted an additional independent review of full-text articles to determine if they adequately addressed the KQs and should be included in this review.
We included RCTs in which the control group was matched in time and attention to the intervention group for the purpose of matching expectations of benefit. The inclusion of such trials allowed us to evaluate the specific effects of meditation programs separately from the nonspecific effects of attention and expectation. Our team thought this was the most rigorous way to determine the efficacy of the interventions. We did not include observational studies because they are likely to have a high risk of bias due to problems such as self-selection of interventions (since people who believe in the benefits of meditation or who have prior experience with meditation are more likely to enroll in a meditation program) and use of outcome measures that can be easily biased by participants’ beliefs in the benefits of meditation.
For inclusion in this review, we required that studies reported on participants with a clinical condition such as medical or psychiatric populations. Although meditation programs may have an impact on healthy populations, we limited our evaluation of these meditation programs to clinical populations. Since trials study meditation programs in diverse populations, we have defined clinical conditions broadly to include mental health/psychiatric conditions (e.g., anxiety or stress) and physical conditions (e.g., low back pain, heart disease, or advanced age). Additionally, since stress was of particular interest in meditation studies, we also included trials that studied stressed populations even though they may not have a defined medical or psychiatric diagnosis. We excluded studies among otherwise healthy populations.
PICOTS Element Inclusion Exclusion
ACT = acceptance and commitment therapy; DBT = dialectical behavioral therapy; MBCT = mindfulness-based cognitive therapy; MBSR = mindfulness-based stress reduction; PICOTS = population, intervention, comparison, outcome, timing, and setting; RCT = randomized controlled trial; TM = transcendental meditation
Note: We excluded articles with no original data (reviews, editorials, and comments), studies published in abstract form only, and dissertations.
Population and Condition of Interest Adult populations (18 years or older)
Clinical (medical or psychiatric) diagnosis, defined as any condition (e.g., high blood pressure, anxiety) including a stressor Studies of children (The type and nature of meditation children receive are significantly different from those for adults.)
Studies of otherwise healthy individuals
Interventions Structured meditation programs (any systematic or protocolized meditation programs that follow predetermined curricula) consisting of at least 4 hours of training with instructions to practice outside the training session
Other mindfulness meditation
Other mantra meditation
Other meditation Meditation programs in which the meditation is not the foundation and majority of the intervention
Any of the movement-based meditations, such as yoga (e.g., Iyengar, hatha, shavasana), tai chi, and qi gong (chi kung)
Eye movement desensitization reprocessing
Breathing exercise, pranayama
Any intervention that is given remotely or only by video or audio to an individual without the involvement of a meditation teacher physically present
Comparisons of Interest Active control is defined as a program that is matched in time and attention to the intervention group for the purpose of matching expectations of benefit. Examples include “attention control,” “educational control,” or another therapy, such as progressive muscle relaxation, that the study compares with the intervention.
A nonspecific active control matches only time and attention and is not a known therapy.
A specific active control compares the intervention with another known therapy, such as progressive muscle relaxation. Studies that evaluate only a wait-list/usual-care control or do not include a comparison group
Outcomes See Figure A
All other outcomes
Study Design RCTs with an active control Nonrandomized designs, such as observational studies
Timing and Setting Longitudinal studies that occur in general and clinical settings None
Table A. Study inclusion and exclusion criteria
Data Abstraction and Data Management
We used DistillerSR (Evidence Partners, 2010) to manage the screening process. DistillerSR is a Web-based database management program that manages all levels of the review process. We uploaded all the citations our search identified to this system.
We created standardized forms for data extraction and pilot tested them. Reviewers extracted information on general study characteristics, study participants, eligibility criteria, interventions, and outcomes. Two investigators reviewed each article for data abstraction. For study characteristics, participant characteristics, and intervention characteristics, the second reviewer confirmed the first reviewer’s data abstraction for completeness and accuracy. For outcome data and risk-of-bias scoring, we used dual and independent review. Reviewer pairs included personnel with both clinical and methodological expertise. We resolved differences between investigators regarding data through consensus.
For each meditation program, we extracted information on measures of intervention fidelity, including dose, training, and receipt of intervention. We measured duration and maximal hours of structured training in meditation, amount of home practice recommended, description of instructor qualifications, and description of participant adherence, if any.
For each KQ, we created a detailed set of evidence tables containing all information abstracted from eligible studies.
To display the outcome data, we calculated relative difference-in-change scores (i.e., the change from baseline in an outcome measure in the treatment group minus the change from baseline in the outcome measure in the control group, divided by the baseline score in the treatment group). However, many studies did not report enough information to calculate confidence intervals for the relative difference-in-change scores. When we evaluated point estimates and confidence intervals for just the postintervention or end-of-study differences between groups and compared these with the point estimates for the relative difference-in-change scores for those time points, some of the estimates that did not account for baseline differences appeared to favor a different group (e.g., treatment or control) when compared with the estimates that accounted for baseline differences. We therefore used the relative difference-in-change scores to estimate the direction and approximate magnitude of effect for all outcomes. For the purpose of generating an aggregate quantitative estimate of the effect of an intervention and the associated 95-percent confidence interval, we performed meta-analysis using standardized mean differences (effect sizes) calculated by Cohen’s method (Cohen’s d). We also used these to assess the precision of individual studies, which we factored into the overall strength of evidence (SOE). For each outcome, we displayed the resulting effect-size estimate according to the type of control group and duration of followup. Some studies did not report enough information to be included in meta-analysis. For that reason, we decided to display the relative difference-in-change scores along with the effect-size estimates from meta-analysis so that readers can see the full extent of the available data.
We considered a 5-percent relative difference-in-change score to be potentially clinically significant, since these studies were looking at short interventions and relatively low doses of meditation. In synthesizing the results of these trials, we considered both statistical and clinical significance. Statistical significance is determined according to study-specific criteria; we reported p-values and confidence intervals for these where present.
Trials used either nonspecific active controls or specific active controls (TableA, Figure A). Nonspecific active controls (e.g., education control or attention control) are used to control for the nonspecific effects of time, attention, and expectation. Comparisons against these controls allow for assessments of the specific effectiveness of the meditation program above and beyond the nonspecific effects of time, attention, and expectation. Such a comparison is similar to a comparison against a placebo pill in a drug trial, where one is concerned with the nonspecific effects of interacting with a provider, taking a pill, and expecting the pill to work. Specific active controls are therapies (e.g., exercise or progressive muscle relaxation) known or expected to change clinical outcomes. Comparisons against these controls allow for assessments of comparative effectiveness and are similar to comparing one drug against another known drug in a drug trial. Since these study designs using different types of controls are expected to yield quite different conclusions (effectiveness vs. comparative effectiveness), we separated them in our analyses.
Assessment of Methodological Quality of Individual Trials
We assessed the risk of bias in studies independently and in duplicate based on the recommendations in the Evidence-based Practice Center “Methods Guide for Effectiveness and Comparative Effectiveness Reviews” (Methods Guide).28 We supplemented these tools with additional assessment questions based on the Cochrane Collaboration’s risk-of-bias tool.29,30 While many of the tools to evaluate risk of bias are common to behavioral as well as pharmacologic interventions, some items are more specific to behavioral interventions. After discussion with experts in meditation programs and clinical trials, we emphasized four major and four minor criteria. We assigned 2 points each to the major criteria, weighting them more than the minor criteria in assessing risk of bias. We assigned 1 point each to the minor criteria. Studies could therefore receive a total of 12 points. If studies met a minimum of three major criteria and three minor criteria (9–12 points), we classified them as having “low risk of bias.” We classified studies receiving 6–8 points as having “medium risk of bias,” and studies receiving 5 or fewer points as having “high risk of bias”.
Assessment of Potential Publication Bias
We planned to use funnel plots to assess potential publication bias if numerous studies reported on an outcome of interest. We also searched for any trials on clinicaltrials.gov that completed recruitment 3 or more years ago and did not publish results, or listed outcomes for which they did not report results.
Strength of the Body of Evidence
Two reviewers graded the strength of evidence for each outcome for each of the KQs using the grading scheme recommended by the Methods Guide. In assigning evidence grades, we considered four domains: risk of bias; directness, consistency, and precision. We classified evidence into four basic categories: (1) “high” grade, indicating high confidence that the evidence reflects the true effect, and further research is very unlikely to change our confidence in the estimate of the effect; (2) “moderate” grade, indicating moderate confidence that the evidence reflects the true effect, and further research may change our confidence in the estimate of the effect and may change the estimate; (3) “low” grade, indicating low confidence that the evidence reflects the true effect, and further research is likely to change our confidence in the estimate of the effect and is likely to change the estimate; and (4) “insufficient” grade, indicating that evidence is unavailable or inadequate to draw a conclusion.
List of major and minor criteria in assessing risk of bias
Was the control matched for time and attention by the instructors?
Was there a description of withdrawals and dropouts?
Was attrition <20% at the end of treatment? As several studies did not calculate attrition starting from the original number randomized, we recalculated the attrition from the original number randomized.
Were those who collected data on the participants blind to the allocation?
Was the method of randomization described in the article? To answer yes for this question, the trials had to give some description of the randomization procedure.
Was allocation concealed?
Was intent-to-treat analysis used? To answer yes for this question, the trial must impute noncompleter or other missing data, and it must do this from the original number randomized.
Did the trial evaluate the credibility, and if so, was it comparable? If the trial did not evaluate credibility, or if it evaluated credibility but did not find it comparable, then we did not give the trial a point.
aWe assigned 2 points each to the major criteria in assessing risk of bias, and 1 point each to the minor criteria.
We assessed applicability separately for the different outcomes of benefit and harm for the entire body of evidence guided by the PICOTS framework, as recommended in the Methods Guide.28 We assessed whether findings were applicable to various ethnic groups, and whether race, ethnicity, or education limited the applicability of the evidence.
Literature Search Results
The literature search identified 17,801 unique citations. During the title-and-abstract screening, we excluded 16,177 citations. During the article screening, we excluded 1,447 citations. During KQ applicability screening, we excluded an additional 136 articles that did not meet one or more of the inclusion criteria. We included 41 articles in the review.31-71
Most trials were short term, but they ranged from 4 weeks to 9 years in duration. Since the amount of training and practice in any meditation program may affect its results, we collected this information and found a fair range in the quality of information. Not all trials reported on amount of training and home practice recommended. MBSR programs typically provided 20–27.5 hours of training over 8 weeks. The mindfulness meditation trials typically provided about half this amount. TM trials provided 16–39 hours over 3–12 months, while other mantra meditation programs provided about half this amount. Only five of the trials reported the trainers’ actual meditation experience (ranging from 4 months to 25 years), and six reported the trainers’ actual teaching experience (ranging from 0 to 15.7 years).
Of the 41 trials we reviewed, 15 studied psychiatric populations, including those with anxiety, depression, stress, chronic worry, and insomnia. Five trials studied substance-abusing populations such as smokers and alcoholics, 5 studied chronic pain populations, and 16 studied diverse medical populations, including those with heart disease, lung disease, breast cancer, diabetes, hypertension, and HIV.
The strength of evidence on the outcomes of our review is shown in Tables B and C. Since there were numerous scales for the different measures of affect, we organized the scales to best represent the clinically relevant aspects of each affect. For this review, the comparisons with nonspecific active controls provided efficacy data, whereas comparisons with specific active controls provided comparative effectiveness data. We found it difficult to draw comparative effectiveness conclusions from comparisons with specific active controls due to the large heterogeneity of type and strength of control groups. Therefore, we presented our results first for all the comparisons with nonspecific active controls in Table B (efficacy), and then for the specific active controls inTable C (comparative effectiveness).
The direction and magnitude of effect are derived from the relative difference between groups in the change score. In our efficacy analysis (Table B) we found low SOE of no effect or insufficient evidence that mantra meditation programs had an effect on any of the psychological stress and well-being outcomes we examined in these diverse adult clinical conditions.
Mindfulness meditation programs had moderate SOE for improvement in anxiety (effect size