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Yoga for the Treatment of Post-Traumatic Stress Disorder, Generalized Anxiety Disorder, Depression, and Substance Abuse: A Review of the Clinical Effectiveness and Guidelines [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2015 Jun 22.
A total of 495 citations were identified in the literature search. Following screening of titles and abstracts, 413 citations were excluded and 82 potentially relevant reports from the electronic search were retrieved for full-text review. Five potentially relevant publications were retrieved from the grey literature search. Of these potentially relevant articles, 64 publications were excluded for various reasons, while 23 publications met the inclusion criteria and were included in this report. APPENDIX 1: Selection of Included Studies describes the PRISMA flowchart of the study selection.
Additional references of potential interest are provided in APPENDIX 5: Additional References of Potential Interest.
A detailed description of individual study characteristics is provided in Tables A1 to A4 of APPENDIX 2: Characteristics of Included Publications.
Two systematic reviews were identified that assessed the efficacy of yoga as a treatment for multiple medical conditions of relevance to this review.15,16 One systematic review originated in Canada and assessed the efficacy of yoga as a treatment for mood and anxiety disorders. The selection criteria included all study types, with or without a comparator group, and patients with PTSD, GAD and depression.15 The literature was assessed up to July 2008 and included all study types. Details of the inclusion and exclusion criteria were limited. A total of 34 relevant studies were identified. The other systematic review originated in the US and assessed the use of meditation techniques, including various forms of yoga, compared to a wait-list, placebo, or sham control group for the treatment of patients with a medical illness (including patients with depression, GAD, and substance dependence).16 Twenty RCTs published between March 2001 and November 2005 and meeting satisfactory methodological quality were included in the review.
One systematic review was identified in the literature that assessed the use of yoga as a treatment for PTSD.15 Details of this study are described above. No RCT evidence and four open trials were identified in the review. Three of the four studies were based on the Iyengar yoga, a form of yoga derived from Hatha yoga which is defined by its emphasis on correctly executed postures combined with breathing and meditation.15 The remaining study did not specify the type of yoga provided.
Two RCTs that assessed the efficacy of yoga as a treatment for PTSD were identified in the literature search, both of which were conducted in the US and included adult women.17,18 van der Kolk et al.17 included women aged 18 to 58 years who had chronic PTSD and had been unresponsive to prior PTSD treatment (> 3 years). Sixty-four patients were randomized to receive either trauma-informed yoga (based on Hatha yoga which incorporates breathing, postures and meditation) or education classes, both at a frequency of one time per week for 10 weeks (60 minutes per session). Mitchell et al.18 included veteran or civilian women aged 18 to 65 years who screened positive for PTSD. Thirty-eight patients (including nine veterans) were randomized to receive either trauma-sensitive yoga (based on Hatha yoga) or assessments only, both at a frequency of one time per week for 12 weeks (75 minutes per session). Patients in the yoga intervention group were given the option of attending yoga sessions one time per week for 12 weeks or two times per week for 6 weeks. Both studies assessed PTSD and depressive symptoms, as well as affect regulation and emotional control,17 trauma,17 and state and trait anxiety18 pre and post-treatment. Mitchell et al.18 also assessed outcomes at one-month follow-up. Based on the study by Mitchell et al.,18 additional outcome data such as PTSD screening, awareness and attentiveness, psychological flexibility, alcohol risk behaviours, substance use and dependence and symptom perception and management, was reported in two related follow-up studies19,20.
Two systematic reviews were identified in the literature that assessed the efficacy of yoga as a treatment for GAD.15,16 Details of these studies are described above. In the first review, one trial was identified assessing the efficacy of Hatha yoga for the treatment of GAD or panic disorder.15 In the second review, no RCTs were identified.21
One open-label trial was identified in the literature search that assessed the efficacy of SKY yoga (for 22 hours over five or six days) in 41 patients aged 18 to 65 years old who had a primary diagnosis of GAD.22 SKY yoga is classified as a stress reduction program that incorporates postures, breathing and meditation as well as self-reflection, and cognitive-based strategies and education for coping with stress.22 Patients had to be receiving at least eight weeks of standard anxiolytic treatment. Anxiety, coping, depression and other outcomes were assessed during the week prior to the intervention and at one month.
Six systematic reviews were identified in the literature containing 18 relevant and unique RCTs.15,16,23–26 The details of two of the systematic reviews are described above.21,27 The four remaining systematic reviews originated from Germany,23 China,24 the UK,25 and the US.26 One review included pregnant women with either prenatal depression or no prenatal depression,24 and the other reviews included patients with depression, depressive disorder or elevated levels of depression.23,25,26 All systematic reviews were broad in their definition of yoga. One review classified studies as assessing one of: complex yoga, exercise-based yoga, or meditation-based compared to usual care, relaxation or aerobic exercise,23 while another review included exercise based or complex yoga of at least 12 weeks duration compared to usual care or other psychical or mental care such as antenatal exercises or social support.24 Blasubramaniam et al.26 included any sub-type of yoga and Pilkington et al.25 included yoga and yoga-based exercises but excluded meditation or combined and complex interventions. Levels of depression, depressive symptoms, or depression severity were outcomes of interest in all studies. Other outcomes included remission, anxiety, health related quality of life (HRQOL) and acceptability and tolerance.
Three additional RCTs were identified, two from the US,28,29 and one from Germany.30 Two studies recruited women, one study specific to women with postpartum depression,28 and one study for women from the community with MDD or dysthymia.29 The remaining RCT included adult patients with MDD from an inpatient hospital ward.30 The yoga intervention took the form of gentle vinyasa flow yoga (60 min, 16 classes for eight weeks and home practice (30 min, one time per week using a DVD) for women with postpartum depression.28 Vinyasa flow yoga involved a sequence of four categories of poses/techniques: I. breathing and centering techniques, II, Warm-up poses, III. A set of stretches and poses defined as “integrative”, and IV. Floor stretches and relaxation.28 The intervention in the other two studies was Hatha yoga of differing durations and adjunctive treatments.29,30 One study assessed quetiapine fumarate extended release (QXR) or escitalopram (ESC) + Hatha yoga (60 min, one time per week) for five weeks.30 The community-based study assessed Hatha yoga group classes (75 min, one time per week) and home practice (daily with 10 min DVD segments and weekly handouts) for eight weeks.29 Levels of depression, depressive symptoms, or depression severity were outcomes of interest in all studies. Other outcomes included response, stress, anxiety, HRQOL and rumination, and interpersonal sensitivity and hostility. One follow-up study to Kinser 201329 was also identified that assessed outcomes up to week 52,31 all other RCTs measured outcomes at pre-treatment, mid-treatment or immediately following treatment.28–30
Two systematic reviews were identified in the literature that assessed the efficacy of yoga as a treatment for substance abuse.16,26 Details of these studies are described above, and both reviews identified one RCT each. One RCT assessed the efficacy of Hatha yoga as an adjunct to methadone treatment for treating patients with opiate dependence. The other RCT assessed the efficacy of SKY yoga for treating patients with alcohol dependence at a de-addiction centre.
Three RCTs were identified in the literature that assessed the efficacy of yoga as a treatment for patients with substance abuse.32–34 The three studies varied according to number of patients randomized, patient characteristics, yoga type, control group, and outcome measures assessed. In one study, 111 male patients with a diagnosis of substance dependence were recruited from a de-addiction ward in a prison setting and randomized to SKY yoga (one time per day for six weeks) or a control group where patients were instructed to sit for an equivalent amount of time and pay gentle attention to their breath. Functioning, general well-being, and severity of dependence were assessed at pre and post intervention.32 In another study, 81 female patients with heroin dependence were recruited from a residential drug-withdrawal rehabilitation centre and randomized to yoga (one time per day, five days per week for six weeks) plus routine hospital care or routine hospital care alone. Mood status and quality of life were assessed at pre-intervention, three months and six months.33 In the third study, 18 adults with alcohol dependence were recruited from an outpatient clinical and were randomized to yoga (one time per week for ten weeks) plus treatment as usual, or treatment as usual alone (psychotherapeutic and pharmacological interventions). The level of alcohol use was the primary outcome assessed at baseline and six months.34
Five evidence-based guidelines were identified in the literature search. Two guidelines originated in Canada,4,35 one in the US,36 one in Britain,37 and one in Scotland.1 Two guideline documents, one from Canada and one from Britain, provided recommendations for the pharmacological4,37 and psychological4 treatment of individuals with a variety of mental health disorders including GAD and PTSD. One guideline document from Veterans Affairs(VA)/Department of Defense(DoD) provided recommendations for pharmacological and psychotherapeutic treatments for PTSD.36 The remaining two guideline documents, one from Scotland and one from Canada addressed complementary and alternative medicine for the treatment of patients with depression.35,38
A detailed description of individual study critical appraisal is provided in APPENDIX 3: Critical Appraisal of Included Publications.
Two systematic reviews were identified that assessed yoga as a treatment for multiple medical conditions of relevance to this review.15,16 One systematic review assessed the clinical efficacy of yoga for PTSD, GAD and depression,15 and the other systematic review assessed the clinical efficacy of yoga for depression, GAD, and substance dependence.16 No meta-analysis was performed in either review; findings were presented qualitatively. The characteristics and quality of the included studies were assessed and well documented, and the strength of the findings was discussed in the context of the quality of the included trials. Arias et al.16 had a well-defined objective and explicitly stated inclusion and exclusion criteria, while da Silva et al.15 provided limited details regarding their search strategy. Neither study reported searching the grey literature, and study selection was completed either by a single reviewer,16 or had uncertain selection methods.15
The quality of the remaining systematic reviews and clinical studies identified by the literature search will be presented according to the relevant condition.
The quality of the systematic review by da Silva et al.15 that assessed the clinical effectiveness of yoga for adults with PTSD is discussed above.
Two RCTs that assessed the efficacy of yoga as a treatment for PTSD were included.17,18 Due to the nature of the intervention, patient blinding in both studies was not possible. Assessor blinding did not occur in Mitchell et al.,18 and the details of allocation concealment were not described in van der Kolk et al.,17 so it is possible that study assessors may have become unblinded to patient treatment group in this study as well. The results were based on an intention to treat (ITT) analysis in both studies, however the study by Mitchell et al.18 was not adequately powered to detect differences between groups. In both studies, inclusion criteria were limited to women. Additionally, the source population used for recruitment was unclear, making it difficult to apply the intervention to the appropriate population in clinical practice.
The quality of the systematic reviews by da Silva et al.15 and Arias et al.16 that assessed the clinical effectiveness of yoga for adults with GAD are discussed above.
One open-label trial that assessed the efficacy of yoga as a treatment for GAD was included.22 The study results were based on an ITT analysis, using a valid and reliable measure of anxiety (Hamilton depression rating scale for anxiety (HAM-A)) administered by a trained assessor. The quality of this study was limited by inherent study design limitations including the lack of randomization and blinding, and no comparison group. Patient compliance during the study was unknown, and 76% of patients completed the intervention.
Two meta-analyses were included that assessed the efficacy of yoga as a treatment for depression,23,24 both with well-defined objectives and clearly stated inclusion and exclusion criteria. The characteristics and quality of the included studies were assessed and documented, and the strength of the findings was discussed in the context of their quality. The reviews were limited by the high level of heterogeneity (I2 = 0% to 86%;23 and I2 = 60%24) between studies (populations and interventions). Subgroup analyses by intervention types and patient populations were completed; however the interpretation is limited due to the number of studies within each group (n=2 to 3;23 n=2 to 424)
The quality of the systematic reviews by da Silva et al.15 and Arias et al.16 that assessed the clinical efficacy of yoga for adults with depression are discussed above. The remaining two systematic reviews25,26 had explicit objectives and inclusion and exclusion criteria. The characteristics and quality of the included studies were assessed and documented in both studies. Pilkington et al.25 conducted a comprehensive search of the literature including grey literature, and quality appraisal was completed by two independent reviewers. Balasubramaniam et al.26 did not undertake a search of the grey literature and it is uncertain if quality appraisal was completed by two reviewers. There was a high level of heterogeneity between studies (populations and interventions) included in the reviews. Between the two reviews, there was one study assessing the efficacy of laughter yoga, three for SKY yoga (two full SKY programs, one partial SKY program), one for Iyengar yoga, one for Shavasana yoga, one for Broota’s technique and one unspecified type of yoga.25,26
Three additional RCTs were identified that assessed the efficacy of yoga as a treatment for depression.28–30 Due to the nature of the intervention, patient blinding in all three studies was not possible. The study by Buttner et al.28 was conducted with a 1:1 block randomization schedule, a blind assessor, additional analyses to account for missing data, and results based on an ITT analysis. The yoga intervention classes were taught by the primary investigator, and the source population was unclear. Results were also limited to women with postpartum depression. Sarubin et al.30 did not provide sufficient detail regarding randomization or allocation concealment and there was no blinding of the outcome assessor. Patient compliance was unknown, and there was a differential rate of drop-outs between groups. The generalizability of the results was limited due to inadequate presentation of the Hatha yoga intervention. Similar to Sarubin et al.30, the study by Kinser et al.29 did not provide sufficient detail regarding randomization or allocation concealment and it was unclear if the outcome assessor was blinded to patient intervention group. Recruitment was based on volunteer participation which may result in systematic differences between the sample population and the underlying source population. Further, the number of patients who remained in the study for a 52 week follow-up assessment31 was disproportionate between the yoga intervention group and the control group (n=7 and n=2 respectively).
The quality of the systematic review by Arias et al.16 that assessed the clinical effectiveness of yoga for adults with SA is discussed above.
Three RCTs were identified in the literature that assessed the efficacy of yoga as a treatment for patients with substance abuse.32–34 Details of randomization methods were provided by all three studies. Due to the nature of the intervention, patient blinding in all three studies was not possible. Assessor blinding and methods for allocation concealment were described in one study,33 however this study took place in a residential treatment centre, so despite the blinding and allocation concealment procedures, there was a risk of contamination between the intervention and control groups. Given the setting in two of the three studies (prison de-addiction ward32 and a residential treatment centre33) compliance was high. Level of compliance in the outpatient setting in Hallgren et al.34 was not reported and 78% of patients remained in the study to the end of the treatment period. These studies were based on very select patient populations so generalizability of the results is limited.
All five evidence-based guidelines had an explicit scope and purpose.1,4,35–37 All guidelines followed a systematic search for relevant literature except for Baldwin et al.37. All guideline documents had generally explicit recommendations that were linked to the existing evidence base. It was unclear if the preferences of the target population had been consulted in three guidelines.4,35,36 The Canadian guidelines4 included consultation with the Canadian psychiatric community, and there was a wide range of stakeholder involvement in the Scottish guidelines and VA/DoD guidelines.36,38
A detailed summary of individual study findings is provided in APPENDIX 4: Main Study Findings and Author’s Conclusions.
The systematic review by da Silva et al. that assessed the efficacy of yoga for patients with mood or anxiety disorders found that there was evidence for the use of yoga as a monotherapy or in combination with medication for treating patients with PTSD.15 This conclusion was based on evidence from a series of four open-label intervention trials (defined as level three evidence in the review: at least one prospective observational study with at least patients).
Two RCTs assessed yoga interventions (based on the core elements of Hatha yoga) for treating PTSD.17,18 Results from van der Kolk et al.17 suggested that women with chronic PTSD who had been non-responsive to therapy may benefit from a yoga program compared to supportive therapy. Mitchell et al.18 found clinically significant decreases in PTSD symptoms in the yoga intervention group but these clinically significant differences were also found in the assessment-control group. A follow-up study by Dick et al.19 found statistically significant improvements in psychological flexibility in the control group but not the intervention group, and another follow-up study by Reddy et al.20 found non-statistically significant improvements in alcohol and drug use risk in the yoga intervention group compared to the assessment-only control group.
Two systematic reviews were included,15,16 and both concluded that there was insufficient evidence to comment on the efficacy of yoga for treating patients with GAD. The variability in the populations and intervention types of the studies for anxiety make it difficult to apply results clinically.15 One open-label trial assessed the effect of a SKY yoga training course in reducing anxiety in patients with GAD in an outpatient setting who had not previously achieved remission with CBT, mindfulness based training and anxiolytic medication.22 There were statistically significant improvements in levels of anxiety after the completion of the intervention. No comparator group was included in this study.
Six systematic reviews were included,15,16,23–26 all of which provide some evidence for the efficacy of yoga in treating depression. Cramer et al.23 found statistically significant improvements in depression severity and remission rates versus usual care, depression severity, remission rates, anxiety and quality of life compared to relaxation, and statistically significant improvements in depression severity compared to aerobic exercise. Compared to pharmacological treatment and electroconvulsive therapy, massage, and social support, there were no statistically significant differences in changes to depression severity, remission rates, and anxiety respectively.23 Gong et al.24 found that yoga was effective in reducing depressive symptoms in pregnant women. Pilkington et al.25 suggested that there may be benefits of yoga for depressive disorders. Balasubramaniam et al.26 identified four low-quality RCTs (defined as Grade B evidence) for yoga in the acute treatment depression. da Silva et al.15 found level two evidence for the efficacy of yoga (monotherapy or in combination with antidepressants) as a second-line treatment in patients with mild to moderate major depression (defined in the review as at least one double-blind RCT with a placebo or active comparator group). In patients with severe depression, yoga was recommended as a third-line treatment. In patients with dysthymia, there was level 2 evidence for the efficacy of yoga as a monotherapy or adjunctive therapy depending on patient preference.15 Arias et al.16 found supportive evidence for the efficacy of SKY yoga (without meditation) and Shavasana yoga as an adjunct treatment for depression.16 The Shavasana protocol was not explicitly stated in the study, however Shavasana has been described as a “death pose” that typically occurs at the end of the yoga session. The pose involves lying on ones back with eyes closed, awareness of the breath, and consciously releasing any noticeable muscle tension.7
In two meta-analyses, subgroup analyses were possible.23,24 Results were the same regardless of patients being defined as having depressive disorder or having elevated levels of depression except when comparing yoga to usual care in patients with depressive disorder.23 Women with a diagnosis of prenatal depression and those without a diagnosis both benefit from yoga therapy.24 When analysis were divided by type of yoga intervention, results were statistically significant for meditation-based yoga interventions when comparing yoga to relaxation for depression and anxiety.23 No statistically significant differences were found for complex yoga interventions or exercise-based yoga interventions compared to usual care.23 The integrated yoga appears to be more effective than exercise-based yoga for decreasing depression scores.24
Three RCTs were included that assessed the efficacy of yoga for patients with depression.28–30 Buttner et al.28 provided evidence for the short-term efficacy of an eight week yoga intervention for improving depressive symptoms, anxiety and quality of life for women with postpartum depression. The long-term effects of this yoga intervention are unknown. Sarubin et al.30 found that Hatha-based yoga as an add-on to pharmacological treatment did not result in statistically significant improvements in depressive symptoms for inpatients with MDD compared to pharmacological treatment alone. Kinser et al.29 suggested that a community-based eight-week yoga program was an acceptable and feasible treatment for women with MDD. The results were suggestive of greater improvements in rumination in the yoga group, a possible mechanism for improvements in depression that deserves further study. A follow-up study to Kinser et al.29 found that completing approximately 75% of the recommended number of minutes of yoga practice (75 minutes, one time per week, 20 minutes all other days) over the course of eight weeks may offer benefits to patients with MDD by improving depression, ruminations, stress, anxiety and health related quality of life.31
The systematic review by Arias et al.16 found supportive evidence for the use Hatha yoga with methadone treatment for opiate dependence. These results were not superior to methadone treatment alone and there were acceptance and generalizability concerns associated with the yoga therapy.
Three RCTs assessed three different forms of yoga in three different patient populations for treating SA. Sureka 201532 compared Sudarshan Kriya and Practices (SK&P) yoga (one time per day for six weeks) to a control group that were instructed to sit and pay gentle attention to their breath for the same duration of time. There were significant improvements in general well-being and anxiety for patients in the yoga intervention group compared to the control group. There were no significant differences between groups for depression, self-control or vitality. Hallgren et al.34 found that yoga was a feasible adjunct treatment for treating alcohol dependence. Patients in the yoga intervention group had a higher baseline level of drinking compared to the control group and there were positive, non-significant changes in alcohol consumption at six month follow-up, numerically greater than that experienced by the control group. Zhuang et al.33 found that yoga may be beneficial as an adjunct treatment for women undergoing outpatient detoxification treatment for heroin dependence. Women in the yoga treatment group experienced statistically significant improvements in quality of life and mood states after six months of yoga treatment.
Five evidence-based guidelines were included,1,4,35–37 two of which did not find enough evidence for yoga to provide a recommendation.37,38 The other three guidelines identified a limited evidence base for which to provide recommendations and suggested that yoga may be useful in patients with GAD,4 may be considered as an adjunctive treatment in patients with PTSD,36 and may be considered as a second-line adjunctive treatment in mild to moderate MDD, if available.35
There were a limited number of well-conducted studies to assess the efficacy of yoga for treating patients with PTSD, GAD and SA.
Six systematic reviews were available that assessed the efficacy of yoga in treating patients with depression; however, they are limited by the poor methodological quality of the included studies. Methods for allocation concealment were often not documented, and due to the nature of the intervention, patients participating in yoga interventions could not be blinded to treatment allocation arm. Studies often recruited highly selected patient populations, such as women with postpartum depression, patients in a residential substance abuse treatment facility, patients in a prison setting, or patients that were young and fit. Furthermore, given that all of the yoga interventions varied on some level – duration, frequency, components, or style - the pooling and generalization of the efficacy results was difficult.
Except where otherwise noted, this work is distributed under the terms of a Creative Commons Attribution-NonCommercial- NoDerivatives 4.0 International licence (CC BY-NC-ND), a copy of which is available at http://creativecommons.org/licenses/by-nc-nd/4.0/
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