Using Mindfulness- and Acceptance-Based Treatments With Clients From Nondominant Cultural and/or Marginalized Backgrounds: Clinical Considerations, Meta-Analysis Findings, and Introduction to the Special Series

Abstract

A growing body of research suggests that mindfulness- and acceptance-based principles can increase efforts aimed at reducing human suffering and increasing quality of life. A critical step in the development and evaluation of these new approaches to treatment is to determine the acceptability and efficacy of these treatments for clients from nondominant cultural and/or marginalized backgrounds. This special series brings together the wisdom of clinicians and researchers who are currently engaged in clinical practice and treatment research with populations who are historically underrepresented in the treatment literature. As an introduction to the series, this paper presents a theoretical background and research context for the papers in the series, highlights the elements of mindfulness- and acceptance-based treatments that may be congruent with culturally responsive treatment, and briefly outlines the general principles of cultural competence and responsive treatment. Additionally, the results of a meta-analysis of mindfulness- and acceptance-based treatments with clients from nondominant cultural and/or marginalized backgrounds are presented. Our search yielded 32 studies totaling 2,198 clients. Results suggest small (Hedges' g=.38, 95% CI=.11 − .64) to large (Hedges' g=1.32, 95% CI=.61 − 2.02) effect sizes for mindfulness- and acceptance-based treatments, which varied by study design.

A growing body of treatment outcome research suggests that the integration of acceptance and mindfulness principles with cognitive behavior therapies shows promise in ameliorating human suffering and improving quality of life (Baer, 2003; Grossman, Niemann, Schmidt, & Walach, 2004). Acceptance- and mindfulness-based principles have been effectively integrated into behavioral treatment of borderline personality disorder (Linehan, 1993), depression (Bohlmeijer, Fledderus, Rokx, & Pieterse, 2011) and depression relapse (Segal, Williams, & Teasdale, 2002), bipolar disorder (Williams et al., 2008), substance abuse (Bowen et al., 2009; Hayes, 2004; Marlatt, 2002), anxiety disorders (Orsillo & Roemer, 2005), eating disorders (Baer, Fischer, & Huss, 2005), psychosis (Bach & Hayes, 2002; Gaudiano & Herbert, 2006), chronic pain (Dahl, Wilson, Luciano, & Hayes, 2005) and stress reduction (Kabat-Zinn, 2003) with favorable outcomes. Despite growing evidence for the efficacy of acceptance- and mindfulness-based treatments across a range of disorders, the generalizability of these findings is limited by samples that do not represent the full demography of the U.S. population. In particular, research on the relevance to and acceptability of these treatments with individuals from nondominant, traditionally underserved backgrounds is in its infancy.

The demographic composition of the United States is shifting and rapid growth is predicted for groups that have traditionally been underserved with regard to mental health services. In approximately 30 years, it is projected that non-Hispanic, single race Whites will become the minority in the U.S. (U.S. Census Bureau, 2008). Further, by 2030, nearly one in five U.S. residents are predicted to be aged 65 or older (Vincent & Velkoff, 2010). Thus, considering the ways in which traditional psychotherapy practices may not fit with the values and worldviews of this changing population has never been more important. Additionally, despite the growing population of racial and ethnic minorities and the significant increase in attention to cultural competence in mental health treatment, inequities in access to quality mental health services continue to exist (U.S. Department of Health and Human Services, 2010). Some have argued that prior to conducting costly randomized controlled trials of standard evidence-based therapies with underserved populations, guidelines about possible treatment adaptations should be established, with careful attention to maintaining the fidelity to treatment principles (Lau, 2006). At the same time, some critics contend that adapting evidence-based treatments for different cultural groups is inefficient and unjustified (Elliott & Mihalic, 2004). Although it is certainly true that a goal of developing treatment variations for every cultural group is impractical and likely unhelpful, broadly disseminating evidence-based treatments without considering the culturally relevant adaptations or refinements that might increase their effectiveness has the potential to widen the gap of mental health disparities in this country.

The overall goal of this series is to provide evidence-based and conceptually grounded suggestions to front-line clinicians working with individuals from nondominant cultural and/or marginalized backgrounds on how acceptance- and mindfulness-based behavioral treatment approaches might be used in ways that are relevant and engaging. We also hope that these suggestions will inform future research of acceptance and mindfulness-based treatment approaches with diverse, underserved populations. This introduction is intended to provide a theoretical background and empirical context for the papers in this series, in addition to an overview of the series. We discuss aspects of acceptance- and mindfulness-based treatment approaches that may lend themselves particularly to culturally responsive treatment, while also highlighting general principles of cultural competence and responsive care that should inform all forms of intervention. Finally, we present findings from a meta-analysis of studies that have examined the efficacy of mindfulness- and acceptance-based treatments with clients from underserved backgrounds.

Acceptance-Based Behavioral Therapies

It has been suggested that Western/dominant cultural values are inherent in many current evidence-based treatments (Benish, Quintana, & Wampold, 2011). In particular, the emphasis placed in cognitive behavioral therapy (CBT) on individualism, present functioning, assertiveness, rationality, and behavior change reflects values that may not be shared by all clients, particularly those from non-Western/nondominant cultural backgrounds (Hays, 2009). In contrast, recent evolutions in CBT highlight the contextual and functional nature of psychological processes and behaviors rather than just their form or frequency, which may be a less value-laden approach to facilitating meaningful behavior change (Hayes, 2004). For example, curiously exploring the function of disruptive thoughts—with the goal of helping clients develop different relationships to the thoughts— may be experienced as more collaborative and less pejorative for clients, as opposed to highlighting the irrational content of those thoughts in order to change the content and frequency of those thoughts. In particular, treatments that emphasize the role of acceptance- and mindfulness-based principles, including Acceptance and Commitment Therapy (ACT; Hayes, Strosahl, & Wilson, 1999), Dialectical Behavior Therapy (DBT; Linehan, 1993), Mindfulness-Based Stress Reduction (MBSR; Kabat-Zinn, 1991), Mindfulness-Based Cognitive Therapy (MBCT; Segal et al., 2002), and integrations of these approaches (e.g., Roemer & Orsillo, 2009), may show promise in addressing some of the unique concerns of individuals from non-dominant cultural and/or marginalized backgrounds.

The terms acceptance-based behavioral therapies (ABBTs) and acceptance- and mindfulness-based therapies have been used to categorize the aforementioned treatment approaches as they share an emphasis on altering clients' relationships to unwanted internal experiences (Roemer & Orsillo, 2009). Whereas traditional CBT approaches generally focus on evaluating the accuracy of internal responses like thoughts or feelings, with the goal of changing their form, ABBT approaches highlight the ways in which certain responses to internal experiences can disrupt functioning and reduce quality of life. Specifically, from an ABBT perspective, client problems are conceptualized as resulting from a pattern of responding to internal experiences with judgment, confusion, and avoidance. Clinically, strategies like mindfulness are used to help clients to compassionately observe their thoughts, emotions, and physical sensations, accept them as transient, inherently human experiences, and become willing to engage in meaningful activities even if doing so could elicit discomfort. While the form and recommended frequency of clinical methods may differ across treatments, cultivating a stance of mindfulness, defined as “an open-hearted, moment-to-moment non-judgmental awareness” (Kabat-Zinn, 2005, p. 24), is one of the core strategies used in many ABBTs to facilitate acceptance of internal experiences and reduce experiential avoidance. MBSR and MBCT recommend extended formal meditation practices whereas DBT utilizes brief, flexible, skills-based practice of mindfulness. The encouragement of engaging in actions that are consistent with one's values (termed as valued actions in ACT [Hayes et al., 1999]) with a willingness to experience the internal experiences that might accompany those actions is another element of some ABBTs, particularly ACT and DBT.

ABBTs and Underserved Populations

There are several ways that ABBTs may be particularly relevant to people from marginalized and/or underserved backgrounds. The therapeutic stance in many ABBTs is that the client's experience is influenced by sociopolitical and historical factors that affect the way that distress is experienced and expressed (Hayes, Luoma, Bond, Masuda, & Lillis, 2006). Emotional distress is viewed as a universal human experience that is inevitable and natural. Thus, a focus of these treatmentsisgenerally to understand the context in which a client is experiencing distress and normalize and validate that distress before encouraging values-consistent behavioral change. This contextualized approach may resonate with clients from nondominant cultural and/or marginalized backgrounds who, due to understandable mistrust of the mental health system, may assume that they will be blamed in therapy for their current circumstances.

The dialectical stance, taken in some acceptance- and mindfulness-based treatments (DBT, ACT), which involves empathically connecting with a client's distress, while also challenging the client to move towards life-enhancing behavioral change as well as an emphasis on engaging in actions consistent with one's values, may resonate with clients who feel that they lack control over their environment due to systemic oppression and discrimination. Given the things that individuals from nondominant cultural and/or marginalized backgrounds have relatively little control over (i.e., oppressive beliefs held by others, systemic oppression, etc.), validating this reality while also helping these individuals identify the actions that are within their control and consistent with what matters most to them, may be extremely helpful. This unique combination of validation and change also has the potential to minimize the power dynamic inherent in traditional psychotherapeutic communication and facilitate a collaborative therapeutic alliance. Additionally, the exploration of client-specific values and valued actions allows for a consideration of the role of cultural and familial expectations that may or may not be in line with a client's own values.

Metaphors, which are often used in ABBTs to illustrate principles of mindfulness and acceptance, may be particularly helpful when working with clients who are from a cultural background where emotional distress and other psychological processes are viewed as a sign of weakness. Perceived stigma has been demonstrated to be related to willingness to receive mental health services among members of traditionally underserved populations such as African Americans and older adults (Conner et al., 2010). Using metaphors to validate distress and illustrate more effective ways of responding to internal experience may serve to normalize psychological challenges. As will be discussed in this series, metaphors can also be easily adapted and personalized to best match the life experiences of a particular client or cultural group.

Psychoeducation and skill-building is a component of many CBTs and is heavily emphasized in many ABBTs. For clients from cultural backgrounds in which psychological difficulties are highly stigmatized or psychotherapy is infrequently utilized, this emphasis may serve to destigmatize psychotherapy and increase engagement. Older adults, in particular, have been found to require more psychoeducation about the process of therapy than younger adults, as they are often less familiar with the purpose and function of therapy (Edelstein, Northrop, & MacDonald, 2009). Roth and Robbins (2004) found that promoting MBSR as an educational program rather than a mental health program was an effective method to address apprehension of seeking mental health services among Hispanic women.

Culturally Competent and Responsive Mental Health Care

Although ABBTs may lend themselves to culturally responsive mental health care in many ways, therapists must also explicitly consider culture and culturally competent care when working with each client. We provide a brief overview of elements of culturally responsive therapy (see Hays, 2008; Lee, Fuchs, Roemer, & Orsillo, 2009; D. W. Sue & Sue, 2003, for more in-depth discussions of these important issues).

“Culture” has been defined broadly as a person's worldview, which is shaped by life experiences and affects the way a person interacts with the world (Pedersen & Ivey, 1993). In understanding some of the relevant dimensions of an individual's cultural identity, Hays (2008) has provided a useful heuristic, known by the acronym ADDRESSING, that includes aspects of a person's (1) Age and generational influences, (2) Developmental and acquired Disabilities, (3) Religion and spiritual orientation, (4) Ethnicity, (5) Socioeconomic status, (6) Sexual orientation, (7) Indigenous heritage, (8) National origin, and (9) Gender. Race, which refers to the social construction of categorizing people into groups on the basis of physical characteristics, is also an important component of one's identity, particularly given the effects that racism can have on a person's sense of self and beliefs about others (cf. Helms & Talleyrand, 1997). An individual's cultural identity is dynamic, in flux, and context dependent as he/she interacts with an ever-changing world. Thus, it has been suggested that it is important to know when to apply general knowledge about cultural groups to understanding a client's experience and when to flexibly individualize treatment to a particular client's circumstances and context (S. Sue, 1998). Those who are from nondominant cultural backgrounds may hold worldviews that are different from the worldview of a dominant culture. These often disparate worldviews are reflective of different experiences in the larger social context.

Clinical psychology has generally been criticized for deemphasizing the importance of viewing individuals within their multicultural and community contexts, instead focusing too narrowly on the individual in isolation (Nagayama Hall, 2005). One cost associated with such a narrow focus is that important sociocultural factors that may be influencing client behaviors will not be explored in therapy, which can inadvertently lead clients to feel that they are to blame for their distress. Clients, particularly those from marginalized backgrounds who may come to therapy with some skepticism about its effectiveness (S. Sue, 2006), may feel misunderstood or unheard when the full context of their life is not attended to, resulting in early termination of therapy (Comas-Diaz, 2006). A critical element of providing culturally competent mental health care involves understanding the barriers and challenges that socially marginalized communities face (D. W. Sue & Sue, 2003). This means that not only do therapists have to explore these barriers in therapy, but they also have to be mindful of their own cultural biases that might prevent them from considering the worldviews of their clients.

Cultural competence has been defined as an approach to therapy, rather than a therapeutic technique (S. Sue, 1998). Therefore, it should be integrated into all aspects of a therapeutic encounter, regardless of the treatment modality. Bernal, Bonilla, and Bellido (1995) proposed a framework for culturally sensitive interventions with ethnic minorities that could be applied more broadly to individuals from nondominant cultural backgrounds and/or marginalized populations. The framework includes eight dimensions that should be integrated into psychological treatments: (1) language, (2) persons, (3) metaphors, (4) content, (5) concepts, (6) goals, (7) methods, and (8) context. Language not only provides important information about a person's culture, but it also relates to the expression and experience of emotions (Barona & Santos de Barona, 2003). Attention to persons reflects the need to attend to similarities and differences between the therapist and the client. Metaphors can be seen as important symbols that reflect cultural values and norms that, if accurately incorporated into treatment, can help a client feel respected and understood. Being knowledgeable about the content of a client's culture can help therapists integrate that content into all aspects of treatment. Careful attention to the cultural context of a client's life is also important when considering the manner in which therapeutic concepts are communicated to a client. Establishing collaborative treatment goals that incorporate the values and norms of a client's culture is crucial. The methods used to achieve the treatment goals must be congruent with a client's culture; that is, the use of clinical methods should be transparent and collaborative. Finally, the sociopolitical contexts of clients' lives, including discrimination, oppression, and socialization, need to considered as they relate to a client's presenting issues and the treatment plan.

In general, mental health providers are most effective when they can flexibly shift their therapeutic focus to meet the needs of their clients (D. W. Sue & Sue, 2003). Client-centered approaches to treatment naturally facilitate culturally responsive mental health treatment. This suggests that evidence-based treatments need to be used flexibly and attentively to ensure that client's needs are not overlooked in the service of adhering rigidly to the treatment. While learning about the customs and norms within a particular community is important, a therapeutic stance that emphasizes awareness of cultural factors that may be related to presenting problems and engagement with treatment is likely to be more helpful. Although it certainly seems that the emphasis on understanding clients' contexts and values and the therapeutic stance characteristic of acceptance- and mindfulness-based behavioral treatments makes them well-suited for use with nondominant cultural and/or marginalized populations, more information is needed to determine their efficacy, explore their acceptability, and identify adaptations that could be helpful. This information should come from clinical research, as well as clinical practice. We hope that this series will serve as a first step towards disseminating information and insights gained from both clinical practice and research that will aid clinicians and researchers working with these populations.

Finally, in an effort to determine the current status of clinical research on the effectiveness of these treatments with nondominant cultural and/or marginalized populations, we recently expanded a previous meta-analytic review of the published empirical literature that used mindfulness- and acceptance-based behavioral treatments with individuals from nondominant cultural and/or marginalized backgrounds (Lee et al., 2009). To our knowledge, this is the first meta-analytic investigation that systematically explores the potential utility of acceptance- and mindfulness-based treatments with clients from diverse backgrounds.

Meta-Analysis of Acceptance- and Mindfulness-Based Behavioral Treatments With Underserved Populations

As noted previously, the literature base on the use of acceptance and mindfulness-based treatments with underserved populations is steadily growing. As a result, we conducted a meta-analytic review of the published and unpublished empirical studies to date that have used mindfulness- and acceptance-based treatments with individuals from nondominant cultural and/or marginalized backgrounds; more specifically individuals who are not traditionally the focus of psychological treatment outcome studies and for whom a consideration of contextual factors is particularly important in treatment.

Method

We undertook a review of the published empirical studies to date (as of September 2011) that have used acceptance- and mindfulness-based behavioral treatments with underserved populations. We conducted an electronic literature search of PsychInfo using the key words Mindfulness, Acceptance, Acceptance and Commitment Therapy (ACT), Acceptance-based Behavior Therapy (ABBT), Dialectical Behavior Therapy (DBT), Mindfulness-Based Stress Reduction (MBSR), and Mindfulness-Based Cognitive Therapy (MBCT). Our search yielded 292 empirical treatment studies with a potential focus on underserved populations. Additionally, we also posted requests for doctoral dissertations, studies that were in press, and unpublished studies on relevant Listservs, which resulted in seven additional studies (three of which did not fit our criteria).

Among the 292 studies yielded by our search, we selected studies with individuals who are not traditionally the focus of psychological treatment outcome studies, are considered marginalized or underserved with respect to mental health treatment accessibility and modality, and for whom a consideration of contextual factors would be particularly important in treatment. Therefore, we selected studies that included only individuals who were either: (a) non-White, (b) non-European American, (c) older adults, (d) nonheterosexual, (e) low-income, (f) physically disabled, (g) incarcerated, and/or (h) individuals whose first language is not that of the dominant culture. We excluded studies that were not conducted in person (i.e., self-help manuals, telephone therapy) and case studies. This resulted in 35 studies from 33 peer-reviewed articles and one dissertation. Three studies reported insufficient information to estimate the effect size (i.e., Bowen et al., 2006, 2009; Liehr & Diaz, 2010) and thus were omitted from the review. This resulted in 32 studies that were retained for analysis, and included 2,198 participants (see Table 1).

Table1. Studies Included in Meta-Analysis.

Authors	Population / Setting	TX	Design	N	Number of Outcoms	g	95%-CI	p
Bradley and Follingstad, 2003	Forensic	DBT	No-Contact	31	9	.96	.23–1.70	.01
Comtois et al., 2007	Community	DBT	Pre-Post	23	7	.43	.01–.76	.01
Evershed et al., 2003	Forensic	DBT	DBT vs.TAU	17	14	.50	-.45–1.45	.31
Garland et al., 2010	60% African American	MBCT-based	MBCT-based vs. Active (Alcohol Support Group)	37	6	.43	-.22–1.07	.19
Gaudiano and Herbert, 2006	88% minority	ACT	ACT+ETAU vs. ETAU	29	8	.37	-.35–1.10	.31
Gregg et al., 2007	Low-SES	ACT	Active (Diabetes Ed)	73	5	.57	.12–1.01	.31
Hayes et al., 2004a	Low-SES	ACT	Active (12-step)	56	9	.21	-.33–.74	.45
Hinton et al., 2004b	Vietnamese refugees	CA- CBT†	WL	12	6	2.75	1.15–4.36	<.01
Hinton et al., 2005b	Cambodian refugees	CA-CBT †	WL	40	7	3.26	2.32–4.21	<.01
Hinton et al., 2009	Cambodian refugees	CA-CBT †	WL	24	5	2.61	1.52–3.69	<.01
Hinton et al., 2011	Latina women	CA-CBT †	Active (Applied Muscle Relaxation)	24	2	1.54	.65–2.43	<.01
James et al., 2011e	Underserved Adolescents	DBT‡	Pre-Post	18	4	.74	.31–1.16	<.01
Lundgren et al., 2006	S. Africa	ACT	Active (Supportive Therapy)	27	4	1.46	.63–2.29	<.01
Lundgren et al., 2008	India	ACT	Active (Yoga)	18	3	.82	-.12–1.77	.09
Lynch et al., 2003	Older Adults (85% White)	DBT	Active (Medication); DBT+MED vs. MED	31	8	.29	-.48–1.05	.46
Lynch et al., 2007 (study 1)	Older Adults (88% White)	DBT	Active (Medication); DBT+MED vs. MED	33	1	.54	-.29–1.38	.20
Lynch et al., 2007 (study 1)	Older Adults (86% White)	DBT	Active (Medication); DBT+MED vs. MED	31	1	.88	.15–1.61	.02
Mendelson et al., 2010	Urban Youth	Mindfulness + Yoga	No-Contact	97	13	.26	-.18–.69	.25
Miller et al., 2000	92% minority	DBT	Pre-Post	27	1	.82	.46–1.18	b.01
Morone et al., 2008	Older Adults (89% White)	MBSR	WL	37	8	.32	-.40–1.03	.38
Pasieczny and Connor, 2011	Inner City Adults (Australia)	DBT	DBT vs. TAU	84	10	.82	.25–1.39	<.01
Rathus and Miller, 2002c	84% minority	DBT	DBT vs. TAU / Pre-Post	67	6	.37	-.27–1.02	.26
Roth and Robbins, 2004	Hispanic	MBSR	No Contact	86	4	.67	.15–1.20	.01
Saavedra, 2008	Community	ACT	WL	26	3	.73	-.06–1.51	.07
Sakdalan et al., 2010	Forensic with Intellectual Disability	DBT Skills Training	Pre-Post	6	4	.76	.07–1.45	.03
Samuelson et al., 2007	Forensic	MBSR	Pre-Post	955	3	.10	.05–.15	<.01
Semple et al., 2010e,f	Inner City Youth	MBCT-C	Pre-Post	20	3	.43	.08–.78	.02
Splevins et al., 2009	Older Adults(Race/ethnicity not reported)	MBCT	Pre-Post	22	4	.57	.28–.85	<.01
Trupin et al., 2002	Forensic	DBT	DBT vs. TAU	90	1	.21	-.20–.62	.32
Wetherell et al., 2010g	Older Adult	ACT	Pre-Post	7	4	.68	.10–1.25	.02
Woodberry and Popenoe, 2008d	Community	DBT	Pre-Post	28	13	.40	.07–.73	.02
Young and Baime, 2010	Older Adult	MBSR	Pre-Post	141	1	.82	.67–.97	<.01

Note. TX=Treatment type stated by the author(s) or derivation thereof: ACT=Acceptance and Commitment Therapy; DBT=Dialectical Behavior Therapy; MBCT=Mindfulness-Based Cognitive Therapy; MBCT-C=Mindfulness-Based Cognitive Therapy for Children; MBSR=Mindfulness-based Stress Reduction. N refers to the number of participants which a study reported that completed the post-treatment assessments and thus were included in the present analyses. In situations where N differed among study measures, we used the highest value. Number of Outcomes refers to a study's outcome variables that were used to compute the effect size. Hedges' g is the effect size estimate reported; .2=small effect, .5=medium effect, and .8=large effect.

^aEffect size was computed by comparing only the active treatment conditions in the study.

^bEffect size was computed by comparing the treatment to the waitlist condition before participants in the waitlist condition received treatment.

^cAuthors reported posttreatment assessments were not administered for the control group, thus for some outcome measures, effect size estimates for between-subjects comparisons were unable to be conducted; instead we used pre-post within-treatment group differences to estimate the effect size.

^dChild and parent ratings were combined to produce an overall effect size for the study.

^eOnly significant results were reported in this study, thus the overall effect size presented is likely an overestimation.

^fEffect size was computed by comparing the pre- to posttreatment change in study measures.

^gAlthough this study was an RCT comparing ACT to CBT, the effect size was computed by comparing the pre- to posttreatment change for the ACT treatment group given the small sample size and rate of attrition in the CBT condition.

^†CA-CBT is an integrative treatment that includes mindfulness principles with traditional CBT principles.

^‡Treatment was described as DBT, but integrated with other techniques including CBT, psychodynamic, client-centered, Gestalt, paradoxical, and strategic approaches during the individual sessions.

Data analysis was conducted using Comprehensive Meta-Analysis software version 2.0 (Borenstein, Hedges, Higgins, & Rothstein, 2005). When effect sizes were not provided, Cohen's d, reflecting the standardized mean difference, was calculated for all outcomes in each study reviewed. Next, an estimation for Hedges' g (Hedges, 1981) was applied as a conservative measure to correct for sample size. Although in most cases the difference between Cohen's d and Hedges' g is negligible, Cohen's d has been shown to have a slight bias and to overestimate the size of the effect, particularly in situations where the sample size is small (Borenstein, Hedges, Higgins, & Rothstein, 2009). For noncontrolled studies, or studies where control data were not provided, the mean difference from pre- to posttreatment was calculated and divided by the pooled standard deviation and subsequently estimated to Hedges' g. In calculating pre-to posttreatment effect sizes we used a global correction of r=.7 (Rosenthal, 1991) applied to study outcome measures. Finally, as we were interested in examining the general salutary effects of acceptance- and mindfulness-based treatments, study outcomes were combined so that each study contributed one composite effect size indicating an overall benefit of treatment. The summary effect was then calculated using a random effects model based on study design.

Results

Table 1 presents the descriptive data for the studies that were included the meta-analysis. The results showed small to large effect sizes (Hedges' g range=.38 to 1.32; where .2 is a small effect, .5 is a medium effect, and .8 is a large effect). Studies that included no-contact or waitlist condition (k=7), on average, demonstrated the largest effect size (g=1.32), followed by studies that used an active treatment (k=9, g=.67) and studies using a pre-post design (k=11, g=.57). Studies comparing an acceptance- or mindfulness-based treatment to treatment as usual demonstrated the smallest effect sizes on average (k=5, g=.38) (see Table 2).

Table 2. Mean Effect Size by Study Type.

Study Type	k	N	g	95%-CI	p-value
Pre-Post a	11	1,234	.57	>.31–.82	<.01
No-Contact/Waitlist	7	331	1.32	>.61–2.02	<.01
Treatment as Usual a	5	307	.38	>.11–.64	.01
Active Treatment	9	327	.67	>.38–.96	<.01
Overall	32	2,198	.69	>.51–.87	<.01

Note. Hedges' g is the effect size estimate reported; .2=small effect, .5=medium effect, and .8=large effect.

^aRathus and Miller (2003) was coded twice (Pre-Post and TAU) as only partial data were reported for between-subject effects and within-subject effects as outcome measures were not administered to control group at posttreatment.

To assess for publication bias, we aggregated the studies and examined the overall effect size (g=.69). First, we calculated Rosenthal's fail-safe N (1979), for the number of studies that would be required to nullify the results of the present analysis. The fail-safe N was 1,986 studies (observed studies z=15.32, p<.001). Trim and fill method (Duval & Tweedie, 2000) was used as a secondary assessment of publication bias. The trim and fill method accounts for those studies with small sample size and extreme effect sizes by removing (i.e., trimming) them through an iterative procedure, and recomputing the effect size at each iteration until the funnel plot increases in symmetry. The trimmed studies are then reinserted (i.e., filled) with mirror images for each back into the analyses to correct for the reduction in variance from the process of removing the studies. The results indicated that removing the asymmetric studies (n=4) had minimal effect on the overall treatment effect size (Trim and Fill Adjusted g=.81, 95% CI [.55 − 1.07]), suggesting an absence of publication bias (see Figure 1).

Figure 1.

Funnel plot of precision by Hedges' g with studies imputed using the trim and fill method (n=4), suggesting absence of publication bias. Studies included the meta-analysis are indicated by open circles. Imputed studies are indicated by darkened circles. Hedges' g for the present analyses are indicated by open diamond. Adjusted effect size and standard error is indicated by darkened diamond.

Discussion

While these initial findings provide some promising support for the utility of acceptance and mindfulness-based treatments with people from diverse, underserved backgrounds, more rigorous clinical research is needed. The median number of participants in each study included in the meta-analysis was n=28, suggesting the need for studies with increased power. Also, relatively few studies included information on the theoretical rationale or considerations in adapting the treatment for a specific demographic group. A theory-driven approach to the adaptation of acceptance- and mindfulness-based treatments could be helpful for bridging the gap between science and practice, as well as dissemination of treatment to practicing clinicians.

Lau (2006) suggests a selective and directive approach to the adaptation of evidence-based treatments for particular communities. The approach is selective in that adaptations are indicated when there is evidence to suggest that there is a clinical problem that occurs in the context of sociocultural factors within a particular community and the standard treatment component or approach does not sufficiently attend to these contextually specific risk factors that may be maintaining the problem behavior. The approach is directive in that it relies on data to inform the adaptations. This approach discourages unnecessary adaptations that threaten the fidelity of the evidence-based treatment. We are currently collecting qualitative data from clients of different ethnic backgrounds in order to obtain some preliminary information on the perceived appropriateness and cultural relevance of an ABBT for GAD that we hope will direct future research efforts on selective adaptations that may be needed.

Overview of the Special Series

In the articles that follow, researchers and clinicians present specific suggestions of how acceptance- and mindfulness-based behavioral treatments might be used with clients from nondominant cultural and/or marginalized backgrounds to optimize relevance and engagement. We invited submissions from clinicians and researchers working with a rrange of underserved populations to provide their clinical recommendations regarding the use of acceptance- and mindfulness-based treatments with the specific populations and treatment settings with which they have experience. Although many important populations are also left out of this series, we believe that this represents an important first step towards understanding the ways in which these treatments already attend to important cultural mechanisms and areas in which adaptations need to be made in order for the treatments to be delivered in a more culturally competent manner.

Through the use of clinical examples, Rucker and West (2013-this issue) present some of the challenges that clinicians might encounter when delivering mindfulness and acceptance-based behavioral treatments with individuals from underserved and underrepresented backgrounds in community settings. The authors offer suggestions for ways to address these challenges.

Dutton, Bermudez, Matas, Majid, and Myers (2013-this issue) present the results of a pilot study examining the use of MBSR as a community-based intervention for low-income, predominantly African American women with a history of intimate partner violence and PTSD. Treatment components and techniques that enhanced treatment feasibility and acceptability in this population are highlighted.

Hinton, Pich, Hofmann, and Otto (2013-this issue) describe how acceptance and mindfulness techniques are utilized in a culturally adapted cognitive behavior therapy targeting the experiences of refugees and ethnic minority populations with PTSD. Through the use of case examples, the ways that acceptance and mindfulness techniques are delivered with Latino/a and Southeast Asian refugee populations with PTSD are illustrated.

Petkus and Wetherell (2013-this issue) provide a theoretical and research-based rationale for using ACT with older adults and describe specific treatment considerations to increase engagement and response when using ACT with older adults.

Finally, Dimidjian and Kleiber (2013-this issue) and La Roche and Lustig (2013-this issue) provide commentaries on the series, including discussion of clinical implications and future directions for research.