Yoga as a Complementary Treatment of Depression: Effects of Traits and Moods on Treatment Outcome

Abstract and Introduction

Preliminary findings support the potential of yoga as a complementary treatment of depressed patients who are taking anti-depressant medications but who are only in partial remission. The purpose of this article is to present further data on the intervention, focusing on individual differences in psychological, emotional and biological processes affecting treatment outcome. Twenty-seven women and 10 men were enrolled in the study, of whom 17 completed the intervention and pre- and post-intervention assessment data. The intervention consisted of 20 classes led by senior Iyengar yoga teachers, in three courses of 20 yoga classes each. All participants were diagnosed with unipolar major depression in partial remission. Psychological and biological characteristics were assessed pre- and post-intervention, and participants rated their mood states before and after each class. Significant reductions were shown for depression, anger, anxiety, neurotic symptoms and low frequency heart rate variability in the 17 completers. Eleven out of these completers achieved remission levels post-intervention. Participants who remitted differed from the non-remitters at intake on several traits and on physiological measures indicative of a greater capacity for emotional regulation. Moods improved from before to after the yoga classes. Yoga appears to be a promising intervention for depression; it is cost-effective and easy to implement. It produces many beneficial emotional, psychological and biological effects, as supported by observations in this study. The physiological methods are especially useful as they provide objective markers of the processes and effectiveness of treatment. These observations may help guide further clinical application of yoga in depression and other mental health disorders, and future research on the processes and mechanisms.

Approximately 75% of US adults have used some form of complementary or alternative medicine (CAM), and about 5% report depression or anxiety as a motivating factor.^[1] CAM practices for depression include yoga, acupuncture, massage, St John's Wort (hypericum), S-adenosylmethionine (SAMe) and folate.^[2] In an unpublished survey of 2133 yoga students conducted by the Iyengar Yoga National Association of the US (IYNAUS), depression ranked among the top five reasons given for participation. Yoga continues to grow in popularity.^[3] A survey conducted in 1998^[4] estimated that 15 million American adults used yoga at least once in their lifetime and 7.4 million during the previous year, and concluded that yoga was often regarded as helpful and without expenditure. Despite the popularity of yoga, there is little systematic research on its clinical application to mental or other health conditions and on the processes underlying its therapeutic potential. Khumar et al.^[5] investigated yoga for depressed university students and found it superior to a no-treatment control; this form of yoga emphasizes deep relaxation and rhythmic breathing. Janakiramaiah et al.^[6] randomized participants to electroconvulsive therapy, imipramine or a Sudarshan Kriya yoga programme focused on rhythmic breathing. They reported remission rates of 93% for electroconvulsive therapy (ECT), 73% for imipramine and 67% for yoga. Studies of non-clinically depressed adults have unclear implications for patients with mood disorders.^[7,8,9] These studies were not placebo-controlled, which is a limitation given the magnitude of placebo effects in the treatment of depression.^[10] Yoga as a complement to anti-depressant medication has not been studied.

An important role in making yoga accessible to the West was played by B. K. S. Iyengar (1918-). The approach he articulated^[11,12] makes it well suited to biomedical application. First, Iyengar yoga employs 'props' (e.g. mats, blankets, blocks, ropes, chairs) that allow beginners to learn the poses gradually and accurately, despite limited experience and flexibility. Second, Iyengar yoga teachers undergo a 3-year training program and are certified by the organization (IYNAUS) at different ranks (Introductory, Intermediate and Senior, with levels within each) according to years of teaching experience and competence. Qualifications are evaluated by written and teaching performance tests, judged by panels of senior teachers. This standardization supports the reproducibility of the program, somewhat like the 'manualized' psychotherapies. Third, Iyengar theory and practice specifies asanas (poses, postures, positions) and sequences of asanas that have therapeutic value for different conditions and states, including depression. For example, certain asanas have been found to enhance positive mood in healthy (non-depressed) participants.^[8]

Iyengar yoga classes typically involve the practice of floor, sitting and standing poses, inversions (head stand, shoulder stand), breathing exercises (pranayama) and short periods of relaxation at the end of each class (savasana--corpse pose). Stretches, twists and extensions or expansions of parts of the body such as the chest are common features. The instructions given by teachers are detailed and continuous during classes, with a focus on awareness of the activity of muscles and joints in conjunction with appropriate breathing patterns to achieve the ideal performance of each asana. An important feature of participation in Iyengar yoga is sustained attention and concentration.

The purpose of this article is to present further data obtained in a study of yoga as a complementary treatment of depressed patients who were taking anti-depressants, but who still had residual symptoms of depression^[13] and to provide evidence underlying the potential of yoga as a treatment of depression.^[14] In the initial sample of 25 adults with major depression, yoga augmentation resulted in significant improvements in mood, and depression severity scores decreased significantly from pre-to post-treatment for these subjects who were taking anti-depressant medications and yet had residual symptoms. An additional group of 12 participants who underwent the same intervention were added to the study sample for the current report.

The focus is on individual characteristics and aspects of the process that affect response to the yoga intervention. We consider various psychological and biological variables related to depression and mood disorders and to presumed effects of psychological and activity-based treatments, including direct measures of depression, demographics, personality tests designed to tap emotional dispositions and symptoms related to depression (such as anger and anxiety), scales of physical and emotional fitness, and measures of autonomic nervous system (ANS) functions.

The ANS measures included blood pressure (BP) and heart rate (HR), and derived indices of heart rate variability (HRV) and baroreflex sensitivity (BRS). High-frequency HRV (HF-HRV) is a measure of respiratory sinus arrhythmia, indicative of parasympathetic control of the heart (vagal tone). The evidence in various studies supports the polyvagal theory of Porges on the role that vagal tone plays in social behavior and the regulation of emotions.^[15] The baroreflex also contributes to parasympathetic control of the heart, and low BRS may be a marker of increased cardiac risk associated with depression or comorbid anxiety.^{[16,17,18,19,20]} HRV and BRS are both relevant to depression, and they are also relevant to the effects of exercise.^[21,22,23]

Studies have found HF-HRV reflections of vagal tone to be lower in depressed psychiatric patients compared with controls,^[24,25,26] although some have not.^[27] There is more consistent evidence that HRV is lower in depressed than non-depressed patients with stable coronary disease,^[22,28] or with a recent history of acute myocardial infarction.^[29] In a recent study in our laboratory,^[30] we compared 28 depressed patients from the present sample with 28 healthy controls on whom we had the same measures. Each pair of subjects was matched for age, gender and ethnicity. The patients showed autonomic function imbalance as indicated by higher low-frequency HRV (LF-HRV) and ratio of low to high frequency HRV (LF/HF), reduced HF-HRV and lower BRS. This dysfunctional pattern was associated with higher HR and BP. HF-HRV has also been related to depressed mood during stressors.^[31] As to the effects of interventions on HRV, research findings are inconsistent. Studies involving pharmacologic treatments for depression^[23,32] and psychotherapy^[33] report an increase in HRV with successful treatments, whereas electroconvulsive therapy^[34] resulted in a decrease in HRV, associated with successful treatment. The discrepancies may reflect the specific intervention employed. As to BRS, in a study of healthy elderly people comparing aerobic exercise and yoga in a 6-week training program, yoga increased BRS but aerobic exercise did not.^[35]

As mood changes are central in depression and mood disorders more generally, we also evaluated the role in treatment outcome of self reports of mood changes occurring during the yoga classes. This focus derives from previous research on the effects of yoga on mood reports in non-depressed healthy subjects, suggesting the potential of yoga for use in the management of clinical major depression. In a form of yoga (Hatha Yoga) that has a strong exercise dimension much like Iyengar yoga, with stretching, balancing and breathing routines, subjects reported being less anxious, tense, angry, fatigued and confused after classes than just before class and, in a second study, yoga and swimming showed comparable positive effects on mood reports.^[36,37] More recently, in a non-clinical sample, reductions in negative mood occurring from before to after yoga classes were greater for subjects scoring higher on scales of depression and anxiety than those scoring lower on these traits.^[8,9,38]

We are reporting on data in a single-group outcome study. Our intention was to estimate the size of the effect, examine process variables and individual differences in treatment outcome, as well as consider practical issues in research of this kind in this population of patients.

Evid Based Complement Alternat Med. 2007;4(4):493-502. © 2007  Oxford University Press

Cite this: Yoga as a Complementary Treatment of Depression: Effects of Traits and Moods on Treatment Outcome - Medscape - Dec 01, 2007.