Introduction

Mindfulness is an innate and universal human capacity that allows for clear thinking and open-heartedness as a means to compassionately alleviate suffering [1]. Mindfulness may be further developed by regularly engaging in formal practices – such as sitting or walking practices – or informal activities – such as eating or washing hands – that ground our attention in both the inner and outer experiences of everyday activities as they occur [2]. These practices center on becoming intentionally aware of one’s thoughts, feelings, and bodily sensations [2,3,4,5,6]. As a parallel process, mindfulness practices focus on cultivating the attitudinal qualities of non-judgement, patience, beginner’s mind, trust, non-striving, acceptance, and letting go [2].

Mindfulness as a modality may be broadly described as an integrated mind–body psycho-spiritual approach originating in the wisdom traditions of Asia, most specifically within Buddhist culture [7]. The term ‘mindfulness’ is however used across a range of disciplines, with each field offering definitions based on the theoretical, methodological and conceptual traditions of the particular discipline [8]. As this review uses the Mindfulness-Based Stress Reduction programme founded by microbiologist Dr Jon Kabat-Zinn as the “gold standard” for contemporary western mindfulness practice, the authors have used Kabat-Zinn’s definition of mindfulness to inform the research: “paying attention in a particular way: on purpose, in the present moment, and non-judgmentally” [2]. It is important to recognize that while MBSR was designed to be appropriate for contemporary, diverse populations, at no time was the intention to divorce the practices from their Buddhist origins. Instead, the capacity to intentionally settle the attention on present-moment awareness within the context of a particular attitudinal approach was offered in a way that recognizes the universality of mindfulness as an expression of our shared humanity [2].

Contemporary mindfulness as an intervention and field of research originated in 1979 when Kabat-Zinn developed the mindfulness-based stress reduction (MBSR) program at the University of Massachusetts Medical School [2]. This program is now used internationally as a manualized, experiential 8-week intervention that involves training in a specific range of formal and informal mindfulness practices [9]. The program enables participants to cultivate mindful awareness in everyday life as a means to develop coping strategies for dealing with stressful and difficult conditions and alleviating both psychological and physiological suffering, leading to an enhanced sense of wellbeing [2,3,4,5, 7, 10,11,12].

Following the success of MBSR, mindfulness has become increasingly popular worldwide amongst clinicians, educators and the general public as a means to cultivate a sense of integrated well-being [2, 3, 5, 10, 13,14,15,16,17,18,19]. Despite the substantial body of literature outlining the many benefits of mindfulness practice within a range of contexts and populations, studies addressing the adaptation, application and value of mindfulness-based interventions (MBIs) for adults in low socio-economic settings are scant. Until now, most mindfulness research has been conducted amongst what may be referred to as WEIRD populations: western, educated, industrialized, rich and democratic, and particularly white, female, middle- to upper-class individuals [10, 12, 20,21,22]. This review seeks to address the gap in the literature by establishing the extent and nature of research on mindfulness-based programmes addressing wellbeing with low socio-economic settings, giving rise to the research question: what are the reported mechanisms used in and resultant outcomes of MBIs in low socio-economic settings? These findings culminate in the development of a program theory which may be useful for the design of mindfulness-based programmes going forward, for the benefit of individuals within low socio-economic settings.

In this review, the term ‘low socio-economic’ is used to describe communities or settings that are characterized by some or all of the following factors: poverty or significant low income; harsh physical living conditions including inadequate housing and homelessness; poor access to resources, including education, health-care and employment opportunities; historical disadvantage caused by cultural and racial factors; and displacement for political or economic reasons [23].

Methods

We conducted a realist review to investigate the complex nature of social interventions, in this case, MBIs for wellbeing in low socio-economic settings. The realist review provided an opportunity to unpack the theories embedded in descriptions of interventions and explore the impact of context on the effectiveness of interventions [24].

Due to the complexity of social interventions, traditional forms of review are unlikely to offer complete or meaningful results, as they do not consider the effects of differing contexts on outcomes [24, 25]. Rather than simply seeking to establish the efficacy of an intervention, realist review offers an explanation of how the intervention worked [26]. Realist reviews explain the causal relationships between mechanisms (M) within a specific context (C) which will have particular outcomes (O): M + C = O [24, 25]. Realist reviews offer a deeper understanding of the intervention which may assist in more effective delivery going forward [24].

We used the methodology for realist review outlined by Pawson et al. (2005) and reported our results following guidelines by Wong et al. as part of the Realist and Meta-narrative Evidence Synthesis – Evolving Standards (RAMESES) project [27]. The first four stages of a realist synthesis are: 1) clarifying the search strategy, including identifying the review question and the nature of the intervention, as well as refining the purpose of the review and exploring program theory; 2) searching for evidence and selecting studies for inclusion; 3) appraising primary studies and extracting data; and 4) synthesizing the data to refine program theory and determining what works for whom, how, and under what circumstances [24].

Defining and clarifying the scope of research

Identifying the review question

Using the M + C = O formula, we defined the review question as follows: within low socio-economic settings (C) what are the mechanisms (M) and outcomes (O) of MBIs for wellbeing? This question was refined into three further questions: 1) within low socio-economic settings, in what contexts do MBIs designed to enhanced wellbeing take place; 2) what are the key mechanisms that benefit or hinder these MBIs; and 3) what are the outcomes of these MBIs?

Clarify the purpose of the review

We conducted this review to establish the feasibility, acceptability, and accessibility of MBIs conducted in low socio-economic settings. This forms part of a larger vision to provide both economically and methodologically sound offerings in low income, low resource communities, toward facilitating social transformation and upliftment.

Developing the program theory

To build the initial program theory, we conducted a preliminary search of the literature to determine the availability of literature [27]. We searched Google Scholar using combinations of the search terms “mindfulness”, “mindfulness-based intervention”, “MBI, “mindfulness-based stress reduction”, “MBSR”, “low income”, “low resource”, “poverty”, “underserved” and “socio-economically challenged”. This broad reading provided the foundation for developing the preliminary program theory; that MBIs for wellbeing, when delivered using certain mechanisms, may benefit adult participants in low socio-economic settings.

Search strategy

Inclusion and Exclusion Criteria

To determine inclusion and exclusion criteria, we followed the population-concept-context (PCC) methodology [28]. We included literature on the adult population, including older adults, and excluded articles focusing on adolescents and children under 18. As per the aim of this review, we retrieved articles focusing specifically on the cultivation of wellbeing. We excluded articles that addressed psychological or medical pathologies, as well as therapeutic interventions specifically addressing drug and alcohol addiction, as mindfulness literature (although limited) has cautioned against including individuals in MBPs if they have a diagnosis of schizophrenia, bipolar disorder, obsessive–compulsive disorder, post-traumatic stress disorder [29], suicidality, untreatable psychosis, clinical depression, social anxiety and other major psychiatric diagnoses [30, 31]. We included articles pertaining to mindfulness interventions that treated tobacco smoking or weight loss/gain (where there were no clinical diagnoses of anorexia, bulimia or obesity), domestic violence, and trauma as these are generic in many low socio-economic populations. and are directly associated with wellbeing. In terms of concept, we only included articles that mentioned mindfulness-based interventions or Mindfulness-based Stress Reduction in the title or abstract. Regarding context, we only included articles that specifically discussed MBIs in low income or low resource communities or settings, as well as populations defined as under-served, poor, marginalized, or disadvantaged. We excluded research conducted in any other settings, or articles that did not specify the setting. We included only peer-reviewed manuscripts, written in English. We excluded non-primary research, books, reviews, summaries, and protocols.

Literature search

An experienced librarian conducted the literature search across a range of databases using the keywords provided by the authors. Whereas the preliminary search represented a broad reading of the field, this formal search is a reproducible and unbiased collection of sources which may be used to test the program theory [25].

Search string

The librarian used the following search string: "mindfulness-based intervention*" or MBI or "mindfulness-based stress reduction*" or MBSR or "mindfulness-based program*" (specifically excluding “Maslach” as MBI can also be “Maslach Burnout Inventory”); AND “low income" or low-income" or "low resource*" or low-resource* or poor or poverty* or "limited resource*" or underprivileg* or Disadvantag* or Underserv* or "socio-economical* challeng*" or marginali* or "low econom*" or low-econom*. The librarian mainly searched the EBSCOHost database, as follows: Academic Search Ultimate, Africa-Wide Information, APA PsycArticles, APA PsycInfo, CAB Abstracts, CINAHL with Full Text, ERIC, GreenFILE, Health Source—Consumer Edition, Health Source: Nursing/Academic Edition, Humanities Source Ultimate, MEDLINE, Sociology Source Ultimate, SPORTDiscus with Full Text, OpenDissertations.

Following identification (N = 112) and deduplication (n = 57) of the records (titles and abstracts), the librarian supplied the search results (n = 55 records) in research information systems (.ris) format. We then imported the records into RAYYAN (www.rayyan.ai) for full-text screening. After identifying and removing further duplicates (n = 4), the authors independently screened the records using the PCC inclusion and exclusion criteria. The authors then met to discuss any disputed articles and subsequently excluded 34 articles. Of the remaining 17 articles, we excluded five articles (two due to duplication, including a journal article based on a thesis, one that was not relevant, one due to inappropriate research design and one because it was a survey), leaving 12 articles to be included in the analysis (Fig. 1).

Fig. 1
figure 1

PRISMA flow diagram showing the process followed to retrieve articles focusing on mindfulness-based interventions (MBIs) to promote wellbeing of adults in low socio-economic settings

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Data appraisal and analysis

Using both the review question and the preliminary program theory as a guide, we designed a data extraction tool using Google Forms. The data extraction tool had the following categories: author; title; year published; journal; aim; purpose of study; research design; population; sampling method; sample size; context; mechanisms/intervention; tools; training and experience of facilitator; outcomes; lessons; and recommendations for further research. Data were then extracted from the articles using the data extraction tool. The authors collectively confirmed the data by checking the charted data against each article. Any discrepancies were discussed and resolved.

Results

Study characteristics

Of the 12 articles, 10 were published in the past decade. There were no articles prior to 2007 that specifically addressed MBSR programs or MBIs in low socio-economic settings. Most (n = 10) of the studies were conducted in the United States (USA) [32,33,34,35,36,37,38,39,40,41]. Only two studies were conducted elsewhere: one in Canada [42] and one in Belgium [16]. The large number of studies conducted in the USA is consistent with current findings that since 1996, 90% of all research on mindfulness has been conducted in USA and the United Kingdon (UK), with no specific research within low socio-economic settings occurring in other regions [43].

Methodologies

Of the 12 articles, two were randomized controlled trials [35, 41], two had a pre-posttest design [16, 38], four were qualitative [33, 39, 40, 42] and five did not report study design.

Population

Seven studies focused solely on women [32, 33, 35,36,37, 40, 41]. Two studies only included pregnant women [36, 41]. Four studies did not mention gender. One article included older adults, between 60 and 90-years-old [40]. Two articles targeted populations that had experienced trauma [35, 37].

Sampling process

Five articles did not describe sampling or inclusion/exclusion criteria for selecting participants [33, 34, 38, 40, 41]. In the remaining eight studies, four mentioned inclusion and exclusion criteria but did not report sampling [32, 36, 39, 44], one reported using volunteers [16]; one used convenience sampling [42] and one used randomized sampling [35]. Only two articles mentioned a recruitment strategy [42, 44].

Sample size

The sample sizes varied considerably. Two studies had a sample size of over 100: 106 and 215 participants respectively [35, 36]. The other 10 studies had sample sizes ranging from 10 to 56 participants. In terms of attrition, three studies reported attrition between 30 and 60% [35, 36, 44], while four reported attrition between 60 and 84% [16, 32, 41, 42]. The remaining six studies did not mention attrition.

Research tools

Various research tools were used in these studies. The only tools that were used in more than one study were the Self-Compassion Scale (n = 2), the Pittsburgh Sleep Quality Index (n = 2), the Perceived Stress Scale (n = 3), the Five Facet Mindfulness Questionnaire (n = 2) and focus groups (n = 3). Five studies used demographic questionnaires [36, 38, 39, 44]. The studies that were concerned with acceptability and feasibility all used different tests [35, 38, 42, 44]. Two studies measured physiological biomarkers: one for cortisol [41] and one reported immunological data [44].

Context

The articles reported varied contexts in which the interventions were offered. One study did not mention the actual context, other than the town where the study was conducted [42]. Two programs were run in shelters for women, one particularly for those experiencing domestic violence and homelessness [33, 35]. Six interventions were run either in clinics or hospitals, including a women’s clinic and a university hospital [32, 34, 36, 39, 41, 44]. One intervention was conducted amongst residents at a low-income senior housing facility [40]; one was run amongst paraprofessionals working within a pre- and primary school setting for children demonstrating emotional, behavioral and academic risk [38]; and one was offered to visitors to public social and health facilities [16]. Only four studies reported the actual geographic location of the intervention [16, 34, 40, 42].

Facilitator training and experience

Five articles did not mention the training and experience of facilitators. One article mentioned that the facilitator had a well-established personal practice and was experienced in adapting mindfulness practices for high-risk youth yet did not refer to any training in mindfulness facilitation [38]. Another article described the facilitators demographically and academically but did not mention experience or qualifications in mindfulness [34]. Two studies described facilitators who were experienced and had received mindfulness facilitator training – one facilitator had online training in the program [41] and, the other facilitator had weekly supervision in the program [36]. Three studies specifically mentioned the qualifications of the facilitators, including that all facilitators were experienced [16, 35, 44].

Mechanisms

Due to the decades-long history of MBSR and the substantial body of research related to its application in a variety of contexts and settings, MBSR may be viewed as the “gold standard” against which other MBIs might be assessed [4]. Alongside this foundational structure, we need to consider how MBSR might be adapted to different situations to meet ethical obligations of providing culturally sensitive service delivery [12]. Table 1 indicates how the 12 articles included in this review retained the core principles of the MBSR “gold standard” (the “warp”) while adapting the interventions to be more context-sensitive (the “weft”) [4]. One study was a straight MBSR [44], seven were adapted MBSRs [16, 32,33,34,35, 40, 42]; three were MBIs that differed from MBSR on certain key elements [36, 38, 41]; and one article tested the effects of two 2-h focus groups on wellbeing [39].

Table 1 Comparison of reviewed articles on mindfulness-based interventions (MBI) with the practice of mindfulness-based stress reduction (MBSR) [4]
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Outcomes

Of the 12 articles reviewed, one article reported that participants believed that mindfulness practice might improve their mental and physical health but did not report clear outcomes [39]. The outcomes of the remaining 12 articles are reported in Table 2. We analyzed the outcomes deductively by aligning the outcomes with mindfulness theory. Mindfulness practice involves understanding our lived experiences by recognizing the nature of our thoughts (cognitive processes), emotions and physical sensations (physiological elements), particularly when experiencing stress. In addition to the outcomes described in the Table 3, one article reported that modifying the MBI in particular ways improved outcomes for people facing extreme poverty and associated difficulties [42]. Zhang and Emory [41] reported that attending more mindfulness sessions reduced depressive symptoms one-month post-intervention. Two articles reported on the acceptability of their initiatives [38, 40], one article reported on feasibility [42], and two articles reported on both acceptability and feasibility [35, 44].

Table 2 Outcomes reported in the reviewed articles describing mindfulness-based interventions (MBI) for wellbeing in low socioeconomic settings
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Table 3 Components of the program theory for a mindfulness-based intervention (MBI) for adults in a low socio-economic setting
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Recommendations to improve MBI outcomes in terms of acceptability, accessibility and feasibility

The articles reviewed recommended several improvements for MBIs in the future. The specific barriers to participation in MBIs were noted as time conflicts, financial constraints [32, 39], lack of childcare, transport, work scheduling, health problems, death of a family member [16], unsafe neighborhoods and unsafe housing [39].

Suggestions for reducing attrition varied depending on the population’s cultural practices, values and needs – particularly for women whose lives tend to be more unpredictable and demanding [32]. Women might be encouraged to participate if there is support in terms of meals, childcare, transport and weekly reminders, as well as financial incentives and offering classes at multiple times during the week [16, 32, 35, 41, 44].

Interventions could be adapted to increase accessibility by delivering the program in the population’s mother-tongue or offering translations and using examples from participants’ lives [32]. Community members could be involved in various ways, such as training community members to be facilitators [35]. This would ensure that facilitators are from a similar cultural background to the participants, especially if they share similar trauma [33, 34, 41]. Facilitators should be appropriately trained in MBI delivery [35]. Participation could also be improved if there were fewer and shorter sessions without compromising positive outcomes [38, 42]. MBIs could be integrated into home practice in such a way that it does not increase daily pressure and stress [35].

One-on-one pre-interventions sessions could help to clarify participants’ understanding and expectations of the program [35]. Participants and facilitators should continuously engage to address concerns and facilitate involvement [35, 39].

Ten articles recommended further research, including replicating existing studies with optimal retention [41]; examining the biological and bio-behavioral parameters of health, stress reactivity, and resilience [16, 44] investigating the dose of practice on response [38]; and exploring the relationship between mindfulness and physical health in low-income populations, including amongst older adults [40].

Several studies suggested larger samples and the use of control groups to confirm the findings of pilot studies, as well as randomized control and longitudinal studies [35, 42]. Studies should ensure bias-free assessment by including larger assessment batteries [38].

Discussion

The results of this review indicate that no studies have been published on the role of MBIs to cultivate wellbeing in low socio-economic settings beyond the “first world” and the USA in particular. This leaves an open field for research on the value of MBIs in low socio-economic settings the world over. The reviewed articles were varied in terms of methodologies, populations, sampling processes, sample sizes, context, training and experience of facilitators, and the mechanisms used. We, therefore, could not compare studies or draw any overall conclusions from the data. What did emerge from the data, however, was that adapting the mechanisms of programs was fundamental for increasing feasibility, accessibility, and acceptability, for example by modifying or reducing the length of the program, sessions and practices; providing manageable home-practice components; and most importantly ensuring that facilitators are appropriately trained and qualified. Most articles recommended strategies to adapt these mechanisms.

To be identified as MBIs, programs need to have certain key features, including upholding the core principles and underlying tenets of mindfulness. Practices should involve sustained intensive training grounded in present moment focus, decentering and an approach orientation [4]. MBSR can be seen as the “gold standard” of MBIs and can be adapted to accommodate the particular needs of participants within their unique contexts. Most of the programs reviewed in this article were described as either MBSRs or adaptations thereof. Few studies defined the actual content of the sessions and the extent to which they incorporated the features of mindfulness. Future research would need to clarify why the intervention should be considered an MBI.

Considering how fundamental the training and experience of the facilitator is to the integrity of the program, it is notable that five articles did not mention the facilitators’ qualifications. Only four articles indicated that the program facilitators were appropriately trained. The remaining articles suggested that while facilitators were knowledgeable and experienced, they were not specifically trained in mindfulness. A key requirement of effective MBIs is that they are developed and run by qualified and experienced facilitators, who are not only grounded in the principles and practices of mindfulness, but also well-versed in adapting material and practices to the requirements of specific populations.

The initial program theory that emerged from the preliminary literature review suggested that MBIs directed towards enhancing wellbeing, when delivered using certain mechanisms, may benefit adult participants in low socio-economic settings. Based on the components of program theory shown in Table 3, we hypothesize that the sense of wellbeing of individuals in low socio-economic settings will improve following participation in an authentic MBI when it has been appropriately adapted through a process of community negotiation and implemented by a trained and competent facilitator. In conclusion we propose that the hypothesis is tested as part of future research within LSES across a broader geographic base.

Limitations

Our findings may be limited by our search strategy. We searched for specific keywords mentioned in the articles’ titles and abstracts. Any article that did not specifically list those keywords would have been automatically excluded, especially articles published in languages other than English. In addition, the sample size was small and largely US-based because this was all that the search revealed. While this certainly limits the generalisability of the findings, it serves as a call for more research into the implementation and outcomes of mindfulness-based well-being initiatives in low socio-economic settings worldwide. A further limitation is that the quality of studies was generally poor due to inadequate methodological information.

Conclusion

The articles reviewed here offer recommendations for how MBIs might be adapted to best serve adults in low socio-economic settings—albeit within “first world” environments. By reviewing the mechanisms and outcomes of the various programs in their respective contexts, we developed a program theory for implementing socio-culturally adapted MBIs in low socio-economic settings, including “third world” or developing countries characterized by varied economies, languages, and cultural practices.

This review may be seen as rigorous in that 1) the literature search was done by a qualified and experienced librarian; 2) multiple databases were searched; 3) all three authors participated in the selection, review, checking and synthesis of the articles, which was 4) conducted iteratively while 5) adhering to the RAMESES reporting standards [27].

Future research could test this program theory in a variety of settings, particularly low socio-economic settings in countries other than the USA. The program theory will ensure the conceptual integrity of MBIs as a modality and also provide a sound platform for adapting and comparing MBIs. The program theory presented here suggests a means to deepen best practice and offers a potentially effective approach to reducing suffering and increasing a sense of wellbeing for adults in low socio-economic settings.