Definition of Meditation

The National Center for Complementary and Alternative Medicine defines meditation as a mind-body method. This category includes interventions that employ a variety of techniques designed to 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. Practitioners generally believe these results in a state of greater calmness, physical relaxation, and psychological balance.¹

Current Practice and Prevalence of Use

A national survey in 2008 shows a marked increase in the number of people meditating, with approximately 10 percent of the population having some experience with meditation.² Many people use meditation to treat stress and stress-related conditions, as well as to promote health.^2,3 In the United States, most meditation training and support has been provided through community resources, and in recent years 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

Researchers have categorized meditative techniques into two forms, those that emphasize “concentration,” such as transcendental meditation (TM) and other mantra-based meditation programs, and those that emphasize “mindfulness,” such as mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT). However this distinction is overly simplistic and may not adequately differentiate the effects of the techniques or the particular skills they teach.^4,5 Both forms appear to involve concentration or focused attention at some point in the training, although the object of attention may differ. Both forms prescribe a mental activity, or non-activity (which itself may be considered an activity by some), associated with the focused attention. Both forms appear to describe an attitude or intention associated with these practices. Furthermore, both forms appear to be dynamic. That is, as a student gains experience, understanding, and/or skill in the practice, their state of awareness and approach to the meditation may evolve. That being said, most descriptions of meditation do not account for this dynamic nature of meditation, and, in fact, some practitioners and instructors may not feel their particular form of meditation has an evolutionary component.

Meditation training is rarely manualized and there are challenges to knowing whether teachers within a practice tradition differ in their understanding of the practice, or whether they emphasize different aspects of the practice. Since meditation is within the mind, and there is not an established way to measure precisely what is being done, there are also significant challenges to knowing what exactly a student is doing when practicing.

The mantra-based techniques practiced in the United States primarily consist of TM, a program established by Maharishi Mahesh Yogi around 1955, and a few others that use a mantra as part of their meditative technique. Many consider TM instruction to be a standardized program that generally consists of daily 1–1.5 hour meetings for 1 week, then periodic meetings, roughly weekly, after the first week for the first month or so, and less frequently after that. Students also receive instructions for home practice and are expected to practice daily. While a mantra is given to each student, there is a dynamic nature to the practice in that the mantra is used as a vehicle to transcend mental activity.⁶ This process has been referred to as “automatic self-transcending”—a process of meditation where one attempts to reach a state of being through meditation. In spite of TM having previously been labeled as a “concentration” form of meditation, some TM experts believe “proper” technique should not teach one to focus attention on the mantra. Rather, one should use the mantra in such a way that the mantra is “innocently” transcended. However, it is not clear how a practitioner can use mantra without focusing attention on it at least initially, nor what other mental activities or attitudes one needs to innocently transcend the mantra. Experts maintain that TM is different from all other forms of mantra meditation, but it is not clear specifically how one transcends the mantra in TM but not in other mantra-style meditations. However, emphasis is placed on the effortlessness of the technique, and electroencephalography has indicated a difference between automatic self-transcendence, and mindful focused attention/nonjudgmental awareness of the present moment.⁶ While some meditative techniques require the ongoing development of skills, some experts feel this is not the case with TM. That is, the technique does not take long to learn, and once learned there is no further skill set to develop.

Mindfulness-based programs include MBSR and its adaptation MBCT. Most consider MBSR and MBCT to be standardized programs. However, instructors vary somewhat in how they teach the programs, partly depending on the clientele. Typically, the programs consist of weekly meetings for 8 weeks, each lasting 2 to 2.5 hours, with an additional 6–8 hour retreat on a weekend day in the middle of the 8-week training. In addition, students receive instructions for daily home practice. MBCT maintains an 8-week course length, similar to MBSR, but instructors modified MBCT for the particular condition of depression. Other adaptations have tried (usually) shorter versions of the program lasting 4 or more weeks targeting different conditions and providing varying amounts of meditation training during that time. Vipassana and Zen are the original practices from which MBSR and other mindfulness-based techniques are derived.⁴

Despite its growing popularity, there remains uncertainty as to what mindfulness exactly is and inconsistency as to how it is taught.⁴ Mindfulness has been described as self-regulating attention toward the immediate present moment and adopting an orientation marked by curiosity, openness, and acceptance.⁷ Others have described mindfulness as including five key components: nonreactivity, observing, acting with awareness, describing, and non-judging.^8-10 Still others have criticized these descriptions, noting that originally the practice emphasized qualities of awareness, which are not adequately captured by these definitions.^11,12 The number of mindfulness-based practices that have been created to target particular conditions, such as MBCT for depression, appear to be more focused on solving problems related to particular conditions rather than cultivating the general qualities of awareness. Thus, the conceptual and practical heterogeneity of mindfulness programs further complicates an understanding of what mindfulness is and how it differs both between and within different programs.

Some “mindfulness” approaches, such as dialectical behavioral therapy and acceptance and commitment therapy, do not use mindfulness as the foundation but rather as an ancillary component. Others, such as yoga and tai chi, involve a significant amount of movement. And although these techniques also contain a meditative component, it is often difficult to ascertain the effects of meditation itself on various outcomes separate from the physiological effects of the exercise component.^13,14 Many of the yoga interventions, in particular, do not clearly indicate how much meditation is involved in the intervention. Qi gong is a broad term encompassing both meditation and movement, as such, we're faced with similar difficulties parsing the effects of movement from the effects of meditation.

It should be noted that although this report evaluates the health effects of meditation programs, meditation historically was not necessarily practiced for a specific health benefit. For many the goal was either philosophical or spiritual enlightenment, a sense of mental and physical peace and calm, self-inquiry, or a combination of these. Our review does not include these more classic goals of meditation, but instead focuses primarily on health benefits. We respectfully acknowledge that some experts regard this focus on specific health outcomes as a diversion from what meditation research should ideally evaluate.

Psychological Stress and Well-Being

As a mind-body method, many believe meditation uses mental processes to influence physical functioning and promote health.¹ The potential effects on function and health are postulated to occur by reducing negative emotions, cognitions, and behaviors; increasing positive emotions, cognitions, and behaviors; and altering relevant physiological processes. While some of these effects can be immediate (i.e., observed within seconds of beginning meditation), the health effects are typically postulated to occur following longer-term practice (i.e., weeks, months, or even years). For the purpose of this review, we use the phrase psychological stress and well-being to refer to a range of negative and positive emotions, cognitions, and behaviors that are known to change with exposure to acute or chronic stress. Emotions include the following: general negative affect, as well as specific emotions such as anxiety and depression; general positive affect, as well as psychological well-being; perceived stress, which generally measures a perceived loss of control; and the mental-health component of health-related quality of life. Cognitions include attention. And behaviors include a range of stress-reactive appetitive behaviors, such as eating, sleeping, smoking, and the use of alcohol or recreational drugs. Although the studies we included did not always directly link these outcomes to stress, these outcomes are generally studied in groups exposed to stress, either due to having a chronic health condition that could be construed as stressful (e.g., cancer, chronic pain, or an anxiety disorder) or due to caring for someone with a debilitating chronic medical condition (e.g., dementia).

Outcomes largely include self-reported changes in psychological stress and well-being, which range from the rare examination of well-being to the more common measurement of negative emotions and behavior, such as anxiety or sleep disturbance. During the development of this report, based on input from technical experts, we decided to include measures of pain since it was thought to be the number-one reason people meditate. We also included measurement of weight as an objective measure of eating behavior. Both pain and weight are therefore included as a fourth Key Question (KQ) based on this input. While there are many physiological/ biological markers of stress, we did not include such intermediate markers in this report because we thought it was important to keep this report focused on outcomes that are clinically meaningful to patients.

Some studies investigate changes in symptoms related to the primary condition (e.g., pain in patients with low back pain, or anxiety in patients with social phobia), whereas others measure emotional symptoms in clinical groups who may or may not present with clinically significant symptoms (e.g., anxiety or depression in individuals with cancer). Because the effectiveness of meditation interventions is unclear and may vary among different subgroups, such as those with a particular clinical condition (e.g., anxiety or pain), we maintained broad inclusion criteria so as to enable subgroup analysis if possible.

Evidence to Date

Studies and 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) to a small to moderate degree.^11,15-33 The populations studied have included healthy adults as well as those with a range of clinical and psychiatric conditions.

The meditation literature has significant limitations related to inadequate control comparisons. For the most part previous reviews have included uncontrolled studies or studies that used control groups for which they did not provide any additional treatment (i.e., usual care or “waiting 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 both participants and trainers, possibly yielding beneficial effects from the added attention, group participation, and support participants receive as well as from the suggestion from trainers that symptoms will likely improve with these increased efforts.^34,35

Due to the heterogeneity of control groups used in past meditation research, we chose to focus this review on only those studies that included a well-defined control group so that we could draw conclusions about the specific effects of meditation on psychological stress and well-being. An informative analogy is the use of placebos in pharmaceutical or surgical trials. Researchers typically design placebos to match to the “active intervention” in order to elicit the same expectations of benefit on the part of both provider and patient. Additionally, placebo treatment includes all components of care received by the “active” group, including office visits and patient-provider interactions in which the provider engages with the patient in the same way irrespective of which group they are randomized to. These nonspecific factors are particularly important to control when evaluation of outcome relies on patient reporting. Since double-blinding has not been feasible in the evaluation of the effects of meditation, the challenge to execute studies that are not biased by these nonspecific factors is more pressing.¹³ As inquiry in this field has advanced over the last few decades, a larger number of trials have moved to a more rigorous design standard by using higher quality controls and blinded evaluators. Thus, there is a clear need to determine the specific effects of meditation based on randomized trials in which expectations for outcome and attentional support from health care professionals are controlled.

Clinical and Policy Relevance

Much uncertainty exists about the differences and similarities between the effects of various forms of meditation.^4,12 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, the conditions for which meditation is efficacious, and whether the type of meditation practiced influences these outcomes. While some reviews have focused on RCTs, many if not most of the included studies involved wait-list or usual-care controls. Thus, we sought to provide information on the specific incremental effects of meditation programs relative to alternative care in which expectations for outcome and attentional support from health care professionals are controlled.

Objectives

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 those 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 in which the respondent describes affect over a period of time. In some studies, clinicians use structured interviews to quantify symptoms of depression. Attention refers to the ability to maintain focus on particular stimuli, and clinicians measure this directly. They measure substance use as the amount consumed or smoked over a period of time, and include alcohol consumption, cigarette smoking, or other drugs, such as cocaine. Studies measure sleep as the amount of time spent sleeping versus awake, or as overall sleep quality. They measure sleep time through either polysomnography or actigraphy, and sleep quality through self-reported questionnaires. Studies measure eating by food diaries to calculate how much energy or fat a person has consumed over a particular period of time. They measure pain similar to affect, by a self-reported questionnaire to assess how much pain an individual is experiencing. It has two dimensions, severity and interference. Studies usually measure pain severity on a numerical rating scale from 0–10 or other self-reported questionnaire. Pain interference measures how much the pain is interfering with life and studies measure it on a self-reported scale. Studies measure weight in pounds or kilograms. The KQs 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)?

Analytic Framework

We present our analytic framework for the systematic review in Figure 1. The figure illustrates the populations of interest, the meditation programs, and the outcomes that we reviewed. This figure depicts the KQs within the context of the Population, Intervention, Comparator, Outcomes, Timing, and Setting (PICOTS) framework described in Table 1. Adverse events may occur at any point after the meditation program has begun.

Figure 1

Analytic framework for meditation programs conducted in clinical and psychiatric populations.