Does Yoga Untie the Pretzel of Anxiety and Depression?
Abstract & Commentary
By Judith L. Balk, MD, MPH, FACOG. Dr. Balk is Associate Professor, Magee-Womens Hospital, University of Pittsburgh; she reports no financial relationship to this field of study.
Synopsis: Yoga may be helpful for psychological disorders. This randomized, controlled trial assessed the effects of yoga vs. wait-list control on anxiety and depression in women referred to a yoga clinic. Depression did not differ either between the two groups or before and after intervention; however, anxiety appeared to decrease significantly in the yoga group, compared to no change reported in the control group. This study is limited by small sample size, unclear description of the participants and recruitment methods, and limited description of the intervention. The analyses are not clearly spelled out, and it appears that the two groups (intervention and control) may not have been equivalent at baseline, although the authors state that the groups were "almost similar." Lastly, the term "prevalence" is consistently used, although it appears that prevalence is not being described.
Source: Javnbakht M, et al. Effects of yoga on depression and anxiety of women. Complement Ther Clin Practice 2009; 15:102-104.
Yoga has often been perceived as a method of stress management that can assist in alleviating depression and anxiety disorders. This study involved a convenience sample of women who were referred to a yoga clinic from July 2006 to July 2007.
All new cases were evaluated on admission using a personal information questionnaire, as well as Beck and Spielberger tests. Participants were randomly assigned to an experimental or a control group. The experimental group (n = 34) participated in twice-weekly yoga classes of 90 minutes duration for two months. The control group (n = 31) was assigned to a waiting list and did not receive yoga. Both groups were evaluated again after the two-month study period.
The average prevalence of depression in the experimental group pre- and post-yoga intervention was 12.82 ± 7.9 and 10.79 ± 6.04 respectively, a statistically insignificant decrease (P = 0.13). However, when the experimental group was compared to the control group, women who participated in yoga classes showed a significant decrease in state anxiety (P = 0.03) and trait anxiety (P < 0.001).
The authors conclude that participation in a two-month yoga class can lead to significant reduction in perceived levels of anxiety in women who suffer from anxiety disorders. This study suggests that yoga can be considered as a complementary therapy or even an alternative to conventional medical therapy in the treatment of anxiety disorders.
Commentary
The idea behind this study holds merit, and other studies have pointed to a therapeutic benefit for yoga in depression and anxiety. The overall design, a randomized controlled trial, is reasonable. The conclusions, however, must be taken with a grain of salt.
The subjects included "new female patient referrals who decided to have yoga experience without any documented psychological disorders or specialist recommendation for taking this therapy." In addition, "cases with history of psychiatric disorders, drug abuse, and experience of yoga practices in past were excluded." Thus, this study of yoga for anxiety and depression effectively did not enroll anyone with a history of anxiety or depression, or anyone referred for anxiety or depression. The article describes the depression prevalence only in the yoga group: Roughly 15% (5 subjects) had either moderate or severe depression. The average baseline depression score in the yoga group was 12.82, and in the control group it was 11.2. Thus, one might expect that even fewer than 15% had moderate or severe depression in the control group. Other issues include no reporting on attrition, recruitment efforts, missing data, and other treatments for depression and anxiety used during the course of the study.
Method of randomization is not stated, and it is not clear if randomization was successful at equalizing the groups. At baseline, state anxiety was 2.29 in the yoga group, and it was 1.13 in the control group. While the authors note that the groups were "almost similar" in state anxiety, this is suspect because the pre-post change of 2.29 to 1.85 in the yoga group was statistically significant (P = 0.03). It is not clear which statistical tests were used for these comparisons, but a statistically significant pre-post change from 2.29 to 1.85 would point to a between-group comparison of 2.29 to 1.13 most likely being significant also.
The anxiety category distributions show that all subjects had at least mild anxiety; there is no category shown for "no anxiety." The distribution of the State-Trait Anxiety Inventory scores is not revealed. The trait anxiety component, which typically reflects one's consistent tendency to react with anxiety to stressful situations, also showed a significant decline after yoga, whereas the control group did not. The text in the article, however, does not match the data in Table 2; it appears to erroneously use the term "experimental group" whereas it is actually referring to the control group. Lastly, the conclusion in the abstract by the authors is that participation in a yoga class can lead to reduction of anxiety in women who suffer from anxiety disorders. However, the women in this study were not selected for having anxiety disorders; the findings might be different for those who had documented anxiety disorders.
Given the methodological issues in this study, can we make a firm conclusion about the role of yoga in anxiety and depression? No. Is it possible that yoga does help with anxiety and depression? Certainly. Recall that the overall design is reasonable, and some significant changes between pre- and post-yoga for anxiety were identified.
As the authors note, several studies demonstrate that yoga improves symptoms associated with depression and anxiety. Yoga significantly reduced symptoms of depression compared to the control group in four of five randomized trials1 and in six of six randomized studies of anxiety,2 although all studies had some limitations. What is the mechanism by which yoga might improve anxiety and depression? One pilot study found that GABA levels increased when yoga practitioners performed yoga compared to when control subjects had a reading period.3 Which component of yoga might be responsible? Relaxation techniques including meditation,4 pranayama (breathing exercises),5 and physical exercise6 can help with symptoms of anxiety and depression. Perhaps social support, attention, and the Hawthorne effect also play a role in the findings. In any case, adding yoga to the armamentarium of treatment options for patients with anxiety or depression is reasonable, as long as standard of care is also met and the patient is thus kept safe from worsening anxiety or depression.
References
1. Pilkington K, et al. Yoga for depression: The research evidence. J Affect Disord 2005;89:13-24.
2. Kirkwood G, et al. Yoga for anxiety: A systematic review of the research evidence. Br J Sports Med 2005;39:884-891.
3. Streeter C, et al. Yoga Asana sessions increased brain GABA levels: A pilot study. J Altern Complement Med 2007;13:419-426.
4. Manzoni G, et al. Relaxation training for anxiety: A ten-years systematic review with meta-analysis. BMC Psychiatry 2008;8:41.
5. Kozasa E, et al. Evaluation of Siddha Samadhi Yoga for anxiety and depression symptoms: A preliminary study. Psychol Rep 2008;103:271-274.
6. Mead G, et al. Exercise for depression. Cochrane Database Syst Rev 2008;(3):CD004366.
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