(This systematic review of the literature was written in March 2014 by the Site Administrator in partial fulfillment of the Masters of Science in Social Work at the University of Louisville)
In 2010, between 153 million and 300 million people aged 15-64 worldwide used an illicit substance at least once in the previous year (UNODC, 2012). According to the Substance Abuse and Mental Health Services Administration (2013), in America alone, an estimated 23.9 million persons age 12 and older are current illicit drug users. Of these, an estimated 22.2 million persons aged 12 and older were classified with substance dependence or abuse in the past year (SAMHSA, 2013). These numbers raise serious concerns because addiction has far reaching health and social consequences. It is estimated that there were between 99,000 and 253,000 deaths globally in 2010 as a result of illicit drug use which includes unintentional overdoses, suicides, HIV and AIDS, and trauma (such as vehicle accidents) (UNODC, 2012). Additionally, drug abuse leads to maladaptive behaviors that interfere with the individual’s ability to function normally in the family, at work, and in the community at a cost to the nation in excess of $600 billion annually (National Institute on Drug Abuse, 2012). Given the prevalence of addiction in the population and the toll it takes on individuals and society, the development of effective treatment interventions is of utmost importance.
Treatment for addiction is delivered by a number of different modalities depending on the needs of the individual and resources available in the community. These include long-term residential treatment, short-term residential treatment, and outpatient treatment programs which combine individual counseling, group therapy, and psycho-education (NIDA, 2012). Common evidence-based approaches to the treatment of addiction include pharmacotherapies (e.g., drug replacement therapies for opioid addiction); and behavioral therapies (e.g., cognitive-behavioral therapy including relapse prevention, cue exposure therapy, contingency management, motivational enhancement therapy, and 12-step facilitation) (Hsu & Marlatt, 2012; NIDA, 2012). The most notable development over the past decade has been application of mindfulness-based techniques including formal meditation practice to the treatment of substance use disorders (Hendershot, Witkiewitz, George & Marlatt, 2011). Because addiction is a chronic condition, relapse is not only possible, but likely over the course of treatment. With relapse rates ranging between 40 and 60% (NIDA, 2012), interventions which include elements of relapse prevention are important in improving treatment outcomes. Mindfulness meditation is believed to reduce the risk of relapse by increasing awareness of negative affective states; increasing frustration tolerance; reducing stress; decreasing craving and enhancing the ability to tolerate drug cravings; decreasing impulsivity and automaticity; fostering acceptance of aversive states; and by cultivating a compassionate view of oneself and others (Bowen, Witkiewitz, Chawla, & Grow, 2011).
Though a number of interventions have incorporated some degree of mindfulness practice into the treatment of addiction, Mindfulness-Based Stress Reduction (MBSR), Mindfulness-Based Cognitive Therapy (MBCT), and Mindfulness-Based Relapse Prevention (MBRP) are unique in their use of formal meditation practice as the primary foundation of relapse prevention (Bowen et al., 2011). The purpose of this paper is to review the literature to determine the effectiveness of MBSR, MBCT, and MBRP in the treatment of substance use disorders. This paper will a) detail the search strategy; b) provide an analysis of each study including a summary of strengths and weaknesses; c) evaluate the overall effectiveness of these interventions; d) discuss implications for social work; and e) recommend areas for further research.
During January 2014, a search for literature was conducted using PsycINFO (EBSCOhost) via the University of Louisville library database. Database searches were performed multiple times using combinations of the following keywords: meditation, mindfulness, relapse prevention, and substance abuse with searches limited to peer-reviewed articles published within the past decade. Initial results yielded a total of 147 hits. Duplicate results were eliminated and abstracts were reviewed to ensure relevancy of included studies. Related systematic reviews were examined and back-referencing of some studies aided in narrowing the number of studies to 32. Application of following inclusion criteria: a) adult population; b) illicit drug or alcohol use; and c) close fidelity to MBSR, MBCT, or MBRP yielded the 10 articles (including 3 secondary analyses) included in this review. Each of these articles was rated according to the quantitative appraisal form set forth in Appendix A. The appraisal ratings and articles are summarized in Appendix B.
Mindfulness-Based Stress Reduction (MBSR)
Marcus et al. (2009) provide the only study to meet inclusion criteria to have utilized a variation of MBSR. This pilot study compared MBTC (MBSR modified for delivery in a therapeutic community) to TAU for reducing stress and increasing treatment retention at a residential facility. The researchers used a convenience sample of 459 residents all of whom met DSM-IV criteria for substance dependence. Participants in the historical comparison group(N=164) received TAU during the first year of the study. Thereafter, the experimental group of 20 cohorts (N=295) received 6 sessions (17 hours) of MBTC. In the historical control group, 76.2% were male and 57.3% were white; while 85.8% were male and 53.6% were white in the experimental group. Biologic and psychological measures were gathered on admission and at months 1, 3, 6, and 9. At the conclusion of the study, the MBTC group had lower overall cortisol levels at 3 months. Both groups showed reduction in stress over time, with MBTC showing significant improvement in subscales of emotional irritability and muscle tension. Additionally, measures of stress were linked to treatment retention. The researchers in this study felt that the communal nature of a therapeutic community precluded randomized control, and therefore the study was undertaken as a quasi-experimental historical control group design. On the other hand, others such as Witkiewitz, Warner, Sully, Barricks & Stauffer (in press), have utilized randomization in a residential setting with success, while acknowledging potential limitations due to interactions of participants across groups. The lack of randomization and use of a non-equivalent historical comparison group in this study leaves open all threats to internal validity. Furthermore variables associated with history significantly confound the results particularly given the fact that the measurements across groups were taken successively. Finally, non-equivalent groups and non-probability sampling make it difficult to generalize findings beyond study participants though the sample size is large relative to similar studies.
Mindfulness-Based Cognitive Therapy (MBCT)
Garland, Gaylord, Boettinger and Howard (2010) provide the only study to have used a variation of MBCT to meet inclusion criteria. The purpose of the study was to compare the therapeutic effects of mindfulness-oriented recovery enhancement (MORE – a modified version of MBCT adapted for treatment of alcohol dependence) to those of an evidence-based alcohol support group (ASG). Participants were a convenience sample of 53 alcohol dependent adults living in a therapeutic company and were randomized to comparison and experimental groups. Most of the participants were male (79.2%) and African American (60.4%). Both MORE and ASG were administered in weekly sessions over 10 weeks. There were no significant pre-intervention group differences nor were there significant differences in attrition or attendance. The MORE group demonstrated significantly reduced stress and alcohol thought suppression as compared to the control intervention. Both interventions led to statistically significant reductions in psychiatric symptoms, and MORE had high perceived treatment credibility and program adherence. Even though most threats to internal validity were controlled by the experimental design, it is difficult to generalize the beyond the small nonprobability homogenous sample. Furthermore, as Marcus et al. (2009) and Witkiewitz et al. (2013) have noted, randomization as a means to establish internal validity is undermined in a communal setting due to the interaction of control and experimental groups.
Mindfulness-Based Relapse Prevention (MBRP)
Zgierska et al. (2008) conducted a study that utilized an adaptation of MBRP known as mindfulness meditation relapse prevention (MMRP). The purpose of the study was to assess the use of meditation as an adjunct for treatment of alcohol dependence in an outpatient setting. Participants were a convenience sample of 19 individuals recruited from collaborating community-based intensive outpatient programs – 53% were women, and 84% were white. Participants attended weekly 2-hour classes over a period of 8 weeks. Interviews were administered at baseline and follow-up (4, 8, 12, and 16 weeks). Biologic measures were also added to the protocol. Results of the study indicate that those who used meditation as adjunct to treatment reported reduction in some aspects of drinking, improved mental health and stress-related outcomes, and high levels of satisfaction with intervention. Of the studies reviewed, this one rated the weakest. The lack of a control group and the small convenience sample seriously undermine both internal and external validity. Without an appropriate control group, it is impossible to know to what extent meditation, participation in the study itself, effects of concomitant therapy, or just the natural progress of recovery contributed to participant improvement. Notwithstanding these limitations, this pilot study did demonstrate that the methods used were feasible for future studies that might employ larger samples and randomized control.
Bowen et al. (2009) conducted the first randomized control trial evaluating the feasibility and initial efficacy of an 8-week outpatient MBRP program. Participants were drawn from a convenience sample and consisted of 168 adults with substance use disorders who had recently completed intensive in-patient or outpatient treatment. The majority of the final sample was male (63.7%) and approximately half were Caucasian (51.8%). Differences in racial composition between groups were controlled by a covariate in analyses. Treatment was delivered to the experimental group in 8 weekly 2-hour group sessions while the TAU control remained in standard outpatient care. Measures were administered at baseline, immediately following the 8-week intervention, and at 2 and 4 months post-intervention. Results demonstrate a significant improvement in MBRP over TAU participants in days of substance use, craving, awareness, and acceptance. Differences were not evident in other aspects of mindfulness, and participants in both groups reported decreases in substance-related problems. Witkiewitz and Bowen (2010) conducted a secondary analysis of the data from this study and found that MBRP appears to influence cognitive and behavioral response to depressive symptoms. These results provide a partial explanation to reductions in post-intervention substance abuse in MBRP group. In another secondary analysis, Witkiewitz, Bowen, Douglas and Hsu (2013) found that a latent factor representing levels of acceptance, awareness and non-judgment mediates the relationship between receiving MBRP and self-reported measures of craving following treatment. While the experimental design in the initial study controls for most threats to internal validity, rates of attrition limit the conclusions that can be drawn regarding treatment effects for the complete sample. Additionally, though the lack of random selection poses limits on extending the study results, because the sample is relatively large and racially diverse, it is reasonable to conclude that the results might be generalized to persons in similarly situated treatment situations.
Brewer et al. (2009) conducted a study using mindfulness training (MT), based on an adaptation of MBRP, for the purpose of assessing its feasibility by comparing it with CBT and its specificity towards stress. Participants were drawn from a convenience sample through media advertisement and clinician referral from a local outpatient treatment facility. A total of 36 individuals met inclusion criteria, including diagnosis of alcohol or cocaine dependence, and were randomly assigned, though only 14 (5 in CBT control, and 9 in experimental) completed the study. At baseline, 72% of participants were male and 62% were Caucasian. All participants received weekly group therapy with CBT delivered over a 12-week period and MT delivered over a 9-week period. Psychological and physiological measures were completed at baseline, weekly, and upon treatment completion. Results indicate that MT did not differ significantly from CBT in treatment retention, treatment satisfaction, or treatment of substance abuse. However, MT demonstrated attenuated psychological and physiological responses to stress provocation as compared to CBT. One of the main strengths of this study – randomization – is seriously undermined by a number of important factors. The attrition rate is such that equivalency of groups was not maintained throughout the study. Additionally, the difference in the length of interventions (12 v. 9 weeks) raises the possibility that results were confounded by unequal treatment doses and other factors related to history. Finally, even if attrition had been adequately controlled, the small non-probability sample limits generalizability beyond the studied sample.
Lee, Bowen and An-Fu (2011) conducted a study evaluating the effects of an adapted version of MBRP in a convenience sample of 24 incarcerated adult Taiwanese males. Participants were randomly assigned to receive the 10-session MBRP intervention or TAU consisting of substance use education. All measures were self-report and administered at baseline, and pre- and post-treatment. Baseline between group differences related to attitudes towards substance abuse and pre-incarceration substance abuse were accounted for in data analyses. Results indicate trend level effects of MBRP on depression and those exposed to MBRP reported increases in negative outcome expectancies. Again, this study utilizes randomization in an experimental design to control for most threats to internal validity, but the small nonprobability sample places considerable limits on external validity. With that being said, the randomization most likely effectively controlled for self-selection bias that can occur when participants volunteer for a particular intervention. In addition, this study is the first of its kind to demonstrate the efficacy of MBRP in a cross-cultural setting.
Witkiewitz et al. (in press) conducted a study to comparing the relative efficacy of MBRP and relapse prevention (RP) in the prevention of substance use relapse. MBRP was adapted in this study for rolling admission rather than the previously described closed cohort studies. Participants were a convenience sample of 105 women drawn from a nonprofit residential treatment center for women referred by the criminal justice system (51% Caucasian for MBRP group; 35% for RP). Participants were randomly assigned to either the MBRP experimental group (twice weekly groups for 8 weeks) or the RP group (adapted to follow the same time commitment as MBRP). Measures were administered at baseline, 4 weeks, 8 weeks post-treatment, and a 15-week follow-up. Women who received MBRP reported significantly fewer drug use days and significantly fewer legal and medical problems at 15-week follow-up. The rate of relapse was comparatively low for both MBRP and RP. In secondary analysis of this data, Witkiewitz, Greenfeld and Bowen (2013), found that racial and ethnic minority women in the study reported significantly fewer drug use days and lower addiction severity index scores at 15 week follow-up. While randomization controlled for a number of threats to internal validity, there are a number of limitations to consider. The nonprobability sample limits external validity beyond this population and treatment context. Additionally, the researchers concede there was a large amount of missing data mostly due in most part to participant attrition and noncompliance though some was systematic. As in several other studies, the residential nature of the treatment setting allowed numerous opportunities for participants to share experiences across conditions thus introducing extraneous influences on results. Though ethical concerns likely preclude use of a no-treatment control in this setting, the experimental design did allow for meaningful comparative analysis of variables.
Discussion and Conclusion
As a result of this review, it is evident that mindfulness meditation is effective in terms of its ability to target triggers that often lead to substance use relapse. In particular, mindfulness meditation reduces stress (Brewer et al., 2009; Garland et al., 2010; Marcus et al., 2009; Zgierska et al., 2008), reduces psychiatric symptoms and improves mental health (Garland et al., 2010; Zgierska et al., 2009), increases thought suppression (Garland et al., 2010), decreases craving while it increases awareness and acceptance (Bowen et. al, 2009), increases negative outcome expectancies (Lee et al., 2011), and lowers the overall addiction severity index (Witkiewitz et al., in press). Furthermore, the replication of these results across treatment settings (therapeutic communities, incarcerated populations, residential treatment, intensive outpatient, and outpatient), across modalities (closed, open, and rolling admissions), among varying racial and ethnic groups, with different drugs of abuse, and across gender suggest that study findings may be extended more generally to the population of substance abusers. This position is strengthened by the fact that 8 of the 10 studies under consideration utilized randomization as a means to control for extraneous influences on dependent variables including those from history, maturation, statistical regression, instrumentation, and testing. Furthermore, three of the studies strengthened internal validity by obtaining biologic measures of stress as a means to corroborate self-report data (Garland et al., 2010; Marcus et al., 2009; Zgierska et al., 2008). However, all of the studies suffered from limitations to external validity due to nonprobability sampling.
Importantly for social work, the feasibility of interventional methods was demonstrated in all of the studies. Several of the studies specifically demonstrated improved treatment retention, perceived treatment credibility and program adherence, and participant satisfaction with the intervention (Garland et al., 2010; Marcus et al., 2009; Zgierska et al., 2008). In addition, several of the studies demonstrated effectiveness of mindfulness meditation against TAU, and specifically with respect to evidence-based CBT (Brewer et al., 2009) and RP (Witkiewitz et al., in press). An area ripe for further research in the context of social work practice is the application of mindfulness meditation in individual counseling. Additionally, while this review attempted to control for variability in meditation technique by considering only those studies which adhere to MBSR, MBCT, or MBRP, future studies could build existing research in other techniques in meditation such as Vipassana (Bowen et al., 2006) and Qigong (Chen et al., 2010).
In summation, this review demonstrates the effectiveness of mindfulness meditation delivered through MBSR, MBCT, or MBRP in treating substance use disorders. Given the prevalence and severity of substance abuse in the general population, these interventions offer an alternative to traditional treatment and an effective means to control relapse triggers.