Definition and Types of Meditation

Meditation has been characterized in many ways in the scientific literature and there is no consensus definition of meditation. This diversity in definitions reflects the complex nature of the practice of meditation and the coexistence of a variety of perspectives that have been adopted to describe and explain the characteristics of the practice. Therefore, we recognize that any single definition limits the practice artificially and fails to account for important nuances that distinguish one type of meditation from another.⁸

Cardoso et al.⁹ developed a detailed operational definition of meditation broad enough to include traditional belief-based practices and those that have been developed specifically for use in clinical settings. Using a systematic approach based on consensus techniques, they defined any practice as meditation if it (1) utilizes a specific and clearly defined technique, (2) involves muscle relaxation somewhere during the process, (3) involves logic relaxation (i.e., not “to intend” to analyze the possible psychophysical effects, not “to intend” to judge the possible results, not “to intend” to create any type of expectation regarding the process), (4) a self-induced state, and (5) the use of a self-focus skill or “anchor” for attention. From a cognitive and psychological perspective, Walsh et al.¹⁰ defined meditation as a family of self-regulation practices that aim to bring mental processes under voluntary control through focusing attention and awareness. Other behavioral descriptions emphasize certain components such as relaxation, concentration, an altered state of awareness, suspension of logical thought processes, and maintenance of self-observing attitude.¹¹ From a more general perspective, Manocha¹² described meditation as a discrete and well-defined experience of a state of “thoughtless awareness” or mental silence, in which the activity of the mind is minimized without reducing the level of alertness. Meditation also has been defined as a self-experience and self-realization exercise.¹³

Despite the lack of consensus in the scientific literature on a definition of meditation, most investigators would agree that meditation implies a form of mental training that requires either stilling or emptying the mind, and that has as its goal a state of “detached observation” in which practitioners are aware of their environment, but do not become involved in thinking about it. All types of meditation practices seem to be based on the concept of self-observation of immediate psychic activity, training one's level of awareness, and cultivating an attitude of acceptance of process rather than content.³

Meditation is an umbrella term that encompasses a family of practices that share some distinctive features, but that vary in important ways in their purpose and practice. This lack of specificity of the concept of meditation precludes developing an exhaustive taxonomy of meditation practices. However, in order to systematically address the question of the state of research of meditation practices in healthcare, we must attempt to identify the components that are common to the many practices that are claimed to be meditation or that incorporate a meditative component, and also clearly distinguish meditation practices from other therapeutic and self-regulation strategies such as self-hypnosis or visualization and from other relaxation techniques that do not contain a meditative component.

Meditation practices may be classified according to certain phenomenological characteristics: the primary goal of practice (therapeutic or spiritual), the direction of the attention (mindfulness, concentrative, and practices that shift between the field or background perception and experience and an object within the field^3,14), the kind of anchor employed (a word, breath, sound, object or sensation^7,15,16), and according to the posture used (motionless sitting or moving).⁷ Like other complex and multifaceted therapeutic interventions, meditation practices involve a mixture of specific and vaguely defined characteristics, and they can be practiced on their own or in conjunction with other therapies. As pointed out by many authors, any attempt to create a taxonomy of meditation only approximates the multidimensional experience of the practices.¹⁷

Meditation Practices as a Part of Healing and Healthcare

The interest in meditation practices as healing strategies comes with the need to acquire a deeper knowledge of the intricate connections between body and mind, and how the mental and spiritual state of an individual directly affects psychological and physical well-being. Meditation practices have been advocated as mind-body treatments for health-related problems and as methods to attain or maintain general wellness. There is a growing body of scientific literature on the effects of meditation practices for a variety of psychiatric disorders such as depression,¹⁸ anxiety,^14,19 panic disorders,²⁰ binge eating disorders,⁷ and substance abuse^21,22 among others. Effects of meditation practices have been also documented using measures of emotional distress²⁰ and cognitive abilities.²³

The effects of meditation practices as complementary treatments for medical conditions other than mental illness have been evaluated using a variety of methods and outcomes. These clinical conditions include hypertension²⁴ and other cardiovascular disorders,^25,26 pain syndromes and musculoskeletal diseases,^18,27,28 respiratory disorders (e.g., asthma, congestive obstructive pulmonary disease),²⁹ dermatological problems (e.g., psoriasis, allergies),³⁰ immunological disorders,²⁷ and treatment-related symptoms of breast and prostate cancer.^18,31

There is also a considerable interest in understanding the physiological and neuropsychological effects of certain meditation practices.^3,32,33 Research conducted in this area has used a variety of methodological approaches and formal evaluations of the methodological quality of this body of evidence have not been conducted.

There is a need to evaluate the evidence that has emerged within the past several decades on the effects of meditation practices in healthcare. Reports on the therapeutic effects of a variety of meditation practices vary greatly across studies. Numerous authors have claimed that most of the studies in this area are methodologically flawed and often have small sample sizes.^3,34,35 The magnitude and direction of the effect often varies from one type of practice to another; however, authors agree that some meditation practices hold some promise of therapeutic benefit for a variety of diseases or conditions. Therefore, there is a great need to clarify and address a host of clinical and research questions regarding the benefits of these interventions.

It is also important to systematically evaluate the role that effect modifiers (e.g., age, gender, duration of practice, other characteristics of meditators, training conditions) may have in influencing the outcomes of the types of meditation. By elucidating important clinical questions regarding the therapeutic effects of meditation practices, consensus on standards of practice can be reached with a view to integrate mind-body approaches more effectively into conventional medical care.

Objectives of the Review

• To provide a descriptive overview and synthesis of information on meditation practices in terms of the main components of the practice, the role of spirituality, training requirements, and criteria for success.
• To conduct a systematic review and synthesis of the evidence on (1) the state of research on the therapeutic use of meditation practices in healthcare, (2) the efficacy and effectiveness of meditation practices in healthcare, (3) the role of effect modifiers for the practices, and (4) the effects of meditation practices on physiological and neuropsychological outcomes.