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Advance Access Publication 28 February 2007
eCAM 2007;4(4)493–502
doi:10.1093/ecam/nel114
Original Article
Yoga as a Complementary Treatment of Depression: Effects of
Traits and Moods on Treatment Outcome
David Shapiro1, Ian A. Cook1, Dmitry M. Davydov2, Cristina Ottaviani3,
Andrew F. Leuchter1 and Michelle Abrams1
1
Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences,
David Geffen School of Medicine, University of California, Los Angeles, CA, USA, 2Department of
Neurophysiology, Moscow Research Center of Narcology, Moscow, Russia and 3Department of Psychology,
University of Bologna, Bologna, Italy
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.
Keywords: anger – anxiety – baroreflex sensitivity – heart rate variability – unipolar major
depression
Introduction
Yoga as a Complementary and Alternative Treatment of
Depression
Approximately 75% of US adults have used some form
of complementary or alternative medicine (CAM), and
For reprints and all correspondence: Dr David Shapiro,
760 Westwood Plaza, Los Angeles, CA 90095-1759, USA.
Tel: 310-825-0252; Fax: 310-206-8826; E-mail: dshapiro@ucla.edu
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)
ß 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/
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Yoga as a complementary treatment of depression
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 nonclinically depressed adults have unclear implications for
patients with mood disorders (7–9). 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.
Iyengar Yoga
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.
Research Objectives
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 antidepressants, 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.
Psychological and Biological Factors Affecting Treatment
Outcome
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 (16–20).
HRV and BRS are both relevant to depression, and they
are also relevant to the effects of exercise (21–23).
Variations in HRV
Studies have found HF-HRV reflections of vagal tone to
be lower in depressed psychiatric patients compared with
eCAM 2007;4(4)
controls (24–26), 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 lowfrequency 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).
Yoga and Mood
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, see also 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.
495
Methods
Participants
This research adhered to ethical research standards and
was approved by the UCLA Institutional Review Board.
Participants were recruited by flyers on campus bulletin
boards, newspaper advertisements and internet notices,
and letters to UCLA clinical faculty. Thirty-seven people
qualified for the study after telephone screening and intake
diagnostic interview, 27 women and 10 men; 33 White,
1 African, and 3 Asian-American; mean (range), age 44.8
(20–71); years of education 16.8 (12–21); BMI 26.7 (20–55);
hours of exercise/week 5.4 (0–30); alcohol drinks/week 1.3
(0–8); 6 students, 3 retirees, 2 unemployed, 26 in professional, technical and white collar occupations.
Based on history and intake diagnostic interview
(Mini-International Neuropsychiatric Interview) (39),
all participants were diagnosed with unipolar major
depression in partial remission; partial remission was
operationalized as having self-reported improvement in
depression severity with pharmacotherapy, but with
residual symptoms reflected by scores on the 17-item
Hamilton Depression Scale (HAM-D) of 7–18.
Participants had to be under the care of a physician
and taking anti-depressant medication for at least 3
months, which continued during the study. The average
Hamilton-D17 (HAM-D) score at intake was 12.5 (7–18);
number of depressive episodes 2.8 (1–6); months on
medication 75.6 (3–336). Participants were excluded
(i) for Axis I diagnoses of bipolar disorders, delirium
or dementia, schizophrenia or other psychotic disorders,
or current substance-related or eating disorders;
(ii) for any medical illness or other conditions that
would pose a safety concern or limit participation;
(iii) for suicidal thoughts or tendencies. Medication
type was as follows: selective serotonin reuptake inhibitor
(SSRI) (n ¼ 15); serotonin-norepinephrine reuptake inhibitor (SNRI) (n ¼ 4); Dopaminergic (n ¼ 4); augmented/
combination drug regimen (n ¼ 14). Medication category
was unrelated to treatment outcome after the yoga
intervention. Individuals with 43 months of prior yoga
experience were excluded. The protocol was approved by
the UCLA Institutional Review Board, and informed
consent was obtained from all participants. Approval for
participation in the study was obtained from each
participant’s own treating physician.
Attendence and Adherence
Out of the 37 people who qualified for the study
and completed the intake procedures, six did not attend
any classes, six attended one class, two attended two
classes, one attended three classes and one attended five
classes. None of these 16 participated in the final
assessment and few responded to telephone inquiries.
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Yoga as a complementary treatment of depression
Based on some limited feedback from these people and
informal observations of research assistants, the issues
were difficult in making a commitment in general,
conflicts with other activities, various inconveniences or
concern about the physical demands. The remaining 21
attended six or more sessions, which we estimated would
be likely to have an effect. These 21 are labeled ‘Ins’ and
the other 16 ‘Outs’. The 16 Outs included 12 women and
4 men; the 21 Ins included 15 women and 6 men.
Of the 21 Ins, four (19%) did not return for the final
assessment or respond to telephone calls. These four
dropouts (all women) attended 10, 12, 12 and 17 sessions.
The remaining 17 are labeled Completers (11 women,
6 men). Thus, the primary participants were the 17 who
attended six or more sessions and who completed
both intake and post-intervention assessments.
Eleven participants (65%) ended the study at remission
levels (REMISS, 57 on HAM-D); for the remaining six
participants (Non-Remiss), one showed a sizable reduction (14–9) and the other five small changes. The REMISS
group contained six women and five men; the NONREMISS group contained five women and one man.
Yoga Procedure
Yoga instruction was provided in three groups of 12–13
participants over an 8-week period, three sessions a week
with a total of 20 sessions per group because of holidays
and incidental cancellations. The 60–90 min classes were
led by three highly experienced certified Iyengar yoga
teachers who rotated over the sessions. The three groups
did not differ in attendance rates or in the HAM-D or
Quick Inventory of Depressive Symptoms (QIDS) scores.
Yoga instruction followed sequences of yoga asanas,
specifically designed by the teachers for this study to
improve mood and alleviate depression, based on the
writing and teaching of BKS Iyengar (11,12) and other
leaders in the field (40,41). There were three classes every
week. One of the classes focused on inverted poses such as
Salamba Sarvangasana (shoulderstand) and Viparita
Karani (supported inversion with bolsters and wall). The
poses were introduced in stages in a progressive manner
week by week according to the ability of the students. The
inversion sequence eventually incorporated poses such as
Adho Mukha Vrksasana (Handstand) and Sirsasana (headstand). A second class each week focused on backbends
which emphasized the expansive chest opening aspects of
back arching asanas in both supported (with chairs,
bolsters, block, etc.) and unsupported versions. The third
class every week focused on restorative poses using props
in a specific manner to support the student in backbends,
inversions and supine poses in order to be able to hold the
poses longer and cultivate the relaxing benefits in the pose
in addition to the other properties in the pose that help
elevate mood. As in the aforementioned inversion
sequence, the back bending and restorative sequences
were also taught in a progressive manner. The yoga
teachers were not given any information about the
participants’ individual characteristics or research data.
A complete list of the asanas may be obtained on request.
Assessments
Psychological Measures
The intake and post-intervention assessment consisted of a
diagnostic interview and health history, demographic
questionnaire and the following personality tests: 17-item
HAM-D, QIDS, SCL, Spielberger Anger Expression Scale
providing indices of Anger In (suppression of anger,
ANGIN) and Anger Out (expression of anger,
ANGOUT), Spielberger Trait Anxiety Inventory (STAI),
Cook–Medley Hostility Scale (indirect hostility),
Pittsburgh Sleep Scale (SLEEP), and the SF-36 shortform health survey, which includes eight dimensions
related to physical and emotional limitations on functioning, bodily pain, general mental health, vitality, general
health, limitations in usual role activities related to
physical and to emotional problems. As significant effects
were found only for the last dimension on emotional
limitations in role activities (RESF36), for simplicity data
for the other SF-36 dimensions will not be presented. The
primary outcome measure of therapeutic effect was the
change in HAM-D score from intake to post-intervention.
Physiological Measures
The electrocardiogram and continuous BP (Finapres)
were measured for 20 min in a soundproof laboratory
under resting conditions with no other tasks or stimulation. Aside from measures of HR and BP, the HR
variances of residual time series (the filtered waveforms)
after a band-pass optimal FIR (finite impulse response)
filtering for alien frequencies and baseline trend
were used to calculate HR variability (HRV, ms2)
in two frequency bands: low frequency (LF-HRV,
0.075–0.125 Hz) and high frequency (HF-HRV,
0.125–0.50 Hz); LF-HRV measures both sympathetic
(SNS) and parasympathetic (PNS) and HF-HRV measures PNS influences on the heart. The specific indices
were the log-transformed variance of HF-HRV and LFHRV, ratio of the log-transformed variance of LF-HRV
to the sum of the logs of the two bands (LFTOT-HRV),
ratio of log-transformed variance of HF-HRV to the sum
of the logs of the two bands (HFTOT-HRV) and ratio of
log-transformed variance of LF-HRV to log-transformed
HF-HRV (LFHF-HRV).
A measure of BRS was obtained by the Sequence
Method developed by Andrew Steptoe (42). BRS indicates
how the ANS adapts to fast changes in BP by measuring
the slope of the change in the cardiac interbeat interval to
a successive increase or decrease in BP over a minimum of
eCAM 2007;4(4)
three beats. For further details of the physiological
recording and data processing methods see reference (30).
497
Table 1. Pre–post yoga intervention changes (completers, n ¼ 17); means
Variable
Pre
Post
P
HAM-D
12.4
6.2
0.001
Mood Ratings
QIDS
11.9
9.4
NS
Participants were asked to rate their moods before and
after each class from 1 ¼ not at all to 5 ¼ very much for
each of the 20 mood items. The moods were selected
to tap three dimensions of affective state: positive
(happy, relaxed, optimistic, confident, content), negative
(stressed, sad, frustrated, irritated, depressed, anxious,
blue, angry, pessimistic) and energy-arousal (attentive,
fatigued, alert, tired, energetic, sleepy) (43).
SCL
1.0
0.7
0.04
STAI
53.0
47.4
0.005
ANGERIN
19.9
18.1
NS
ANGEROUT
15.2
12.5
0.05
MC
15.5
16.0
NS
RESF36
23.1
51.3
0.02
SLEEP
10.2
9.1
NS
HR (bpm)
72.2
71.8
NS
134.0
132.5
NS
SBP (mmHg)
Data Analysis
LF-HRV
6.81
6.51
0.05
Systat (v. 10) was used to analyze the data using withinand between-group t-tests and general linear models
(GLM). An example of the latter is the analysis of the
effects of an independent variable, such as whether
participants achieved remission levels or not versus
the repeated measure of change in HAM-D scores from
pre- to post-intervention. Random regression models (SAS,
Proc Mixed) were used to analyze the longitudinal mood
ratings obtained over the course of the yoga sessions. These
models consider both within- and between-subject variability, and allow for random and fixed effects (mixed
modeling) as well as a variable number of observations per
subject and missing data, such as missed sessions.
HF-HRV
5.53
5.40
NS
LFHF-HRV
1.23
1.22
NS
LFTOT-HRV
0.36
0.36
NS
HFTOT-HRV
0.30
0.30
NS
BRS (ms/mmHg)
6.32
6.39
NS
Results
Predictors of Failure to Complete Yoga Intervention
The 21 Ins and 16 Outs were compared by t-test and
chi-square test on all measures at baseline. They differed
only on one measure; Ins had higher scores on the Anger
In scale (19.3 versus 15.8; P50.02). Scores on the Anger In
scale were negatively correlated with total Anger
(r ¼ 0.50, P50.002) and positively correlated with Trait
Anxiety (r ¼ 0.53, P50.001), Indirect Hostility (r ¼ 0.59,
P50.001) and Months Medication (r ¼ 0.45, P50.01).
Significant Pre–Post Reductions were Shown for HAM-D,
STAI, ANGOUT, SCL, RESF-36 and LF-HRV
For the 17 completers, HAM-D at intake was 12.4 (7–18)
and 6.2 (0–15) at post-intervention (P50.001). All but
two out of the 17 showed a decrease in HAM-D scores.
For all 37 participants, using the last observation carried
forward, thus no change for the 16 Outs and the four
who did not complete the post-assessment, the mean
reduction in HAM-D scores was still significant
(P50.001). For the 17 completers, significant pre-post
reductions (P50.05) were shown for STAI, ANGOUT,
SCL, RESF36 and LF-HRV (Table 1).
REMISS Participants were Less Educated and Exercised
More Often Than NON-REMISS Participants, and the
Two Groups also Differed on HR, BRS and HR
Variability at Intake
Eleven participants (65%) ended the study at remission
levels (REMISS, 57 on HAM-D); for the remaining six
participants, one showed a sizable reduction (14–9) and
the other five small changes. With respect to intake (pre)
measures, REMISS participants differed significantly
(Ps50.05) from NON-REMISS participants on intake
data as follows: less education, more habitual exercise;
lower HR, higher levels of HF-HRV, lower levels of
LFHF-HRV, higher levels of HFTOT-HRV, lower levels
of LFTOT-HRV and higher BRS (Table 2). Given the
activity-oriented intervention, we examined the relationship between the intake measure of habitual exercise and
the physiological measures for all participants.
The various high-frequency HRV measures (vagally
mediated) were positively correlated with hours of
exercise (rs 0.35 to 0.40), and the low-frequency HRV
measures were negatively correlated with exercise
(rs 0.25 to 0.35).
REMISS Participants showed Greater Improvement in
Depressed Mood, Neurotic Symptoms and Middle
Insomnia compared with NON-REMISS Participants, and
the Two Groups also Differed on Changes in HR
Variability Pre- to Post-intervention
Differences between pre- and post-intervention assessment measures were examined as a function of whether
498
Yoga as a complementary treatment of depression
Table 2. Significant differences between REMISS (n ¼ 11) and
NON-REMISS (n ¼ 6) participants at intake (means)
Table 4. Mood ratings pre- and post-yoga classes
Mood
Variable
REMISS
NON-REMISS
P
Education (years)
15.9
18.2
0.01
Exercise (h/week)
9.9
0.8
0.02
Heart rate (bpm)
68.7
78.4
0.04
HF-HRV
6.01
4.90
0.02
HFTOT-HRV
0.31
0.27
0.01
LFTOT-HRV
0.35
0.38
0.03
LFHF-HRV
1.14
1.38
0.01
BRS (ms/mmHg)
7.88
4.58
0.02
Table 3. Significant differences between REMISS (n ¼ 11) and NONREMISS (n ¼ 6) participants pre- and post-yoga (means)
Variable
REMISS
Pre
HAM-D
11.8
Post
3.3
NON-REMISS
Pre
13.3
Post
11.7
P
0.001
QIDS
13.8
6.9
9.5
12.7
0.01
SCL
1.1
0.7
0.8
0.8
0.04
HF-HRV
5.96
5.53
4.89
5.20
0.01
LFHF-HRV
HFTOT-HRV
1.16
0.32
1.19
0.30
1.38
0.28
1.26
0.29
0.02
0.002
participants achieved remission or not, using HAM-D57
for stratification. REMISS participants showed greater
reductions in their QIDS and SCL scores. In addition,
they also showed several physiological effects: a reduction
in HF-HRV and HFTOT-HRV compared with increases
in the NON-REMISS group and a small increase in
LFHF-HRV compared with a small decrease in the
NON-REMISS participants (Table 3).
We also examined each of the 17 items in the HAM-D
to specify which symptom factors in the HAM-D were
most responsive to treatment. The effects indicate
greater improvement in depressed mood (P50.005) and
middle insomnia (P50.005) for REMISS compared
with NON-REMISS participants.
Significant Immediate Changes Seen in Mood
After Each Class
For the 17 completers, all 20 moods showed significant
immediate changes from before to after each class
(all P values 50.0001): negative moods decreased,
positive moods increased, energy/arousal moods
increased (less tired, more energetic, etc.) (Table 4).
Moods did not change significantly over the course of
the sessions with one exception: average levels of ‘happy’
(pre- and post-class ratings) increased over the course of
the sessions (P50.03) and the increases in ‘happy’ from
Pre
Post
Positive
Happy
2.9
3.5
Relaxed
2.6
3.8
Optimistic
2.8
3.3
Confident
2.8
3.4
Content
2.6
3.4
Stressed
2.7
1.5
Sad
2.6
2.0
Frustrated
2.8
1.9
Negative
Irritated
2.6
1.7
Depressed
2.4
1.7
Anxious
2.4
1.5
Blue
2.4
1.7
Angry
2.1
1.6
Pessimistic
2.5
2.0
Attentive
3.1
3.5
Fatigued
3.2
2.4
Alert
3.0
3.6
Energy/Arousal
Tired
3.3
2.6
Energetic
2.4
3.4
Sleepy
3.0
2.3
All pre–post differences, P50.001.
before to after each class became greater over the course
of sessions (P50.03).
The average level of mood ratings over all the
classes differed between REMISS and NON-REMISS
participants as follows: REMISS rated themselves higher
on happy, relaxed, optimistic, confident, and content,
and they rated themselves lower on frustrated, pessimistic, depressed, anxious and blue (Ps50.025).
The differences between REMISS and NON-REMISS
participants for energy/arousal related moods were not
significant.
Comparing the REMISS and NON-REMISS groups,
in five moods, the change in rating from beginning to the
end of class differed significantly. For three negative
moods (frustrated, pessimistic, anxious), the decrease was
greater for the NON-REMISS group, reflecting higher
initial values for this group (Ps50.05). In fact, at the end
of class, the REMISS participants remained lower.
For two energy-related moods (tired, energetic), the
same pattern was shown, less tired and more energetic
for NON-REMISS participants (Ps50.05). In these
cases, the two groups had similar levels at the end of
classes.
eCAM 2007;4(4)
Discussion
Our findings extend prior work examining the therapeutic
effects of yoga on emotional state. First, we found that
beneficial effects not only address the biomedically
defined symptoms of unipolar major depression,
but yield improvements in a more broadly defined set
of reports of mood state experience. Second, these
effects are present at a session-by-session level as well
as accruing over time. Third, pre-intervention autonomic
differences were found between subjects who entered
symptomatic remission with the yoga augmentation and
those who did not, suggesting that it may be possible
to consider prospectively which individuals with
depression may benefit most from complementary
yoga augmentation of anti-depressant medication.
The findings of the benefits of yoga for depressed
patients in partial remission are consistent with previous
studies of depressed patients (5,6) using interventions
that emphasize rhythmic breathing aspects of yoga.
The Iyengar approach in the present study focused
mainly on more active asanas and included only brief
periods of relaxation and breathing exercises. Future
studies will be needed to explore the relative importance
of the various components of yoga practices (e.g. physical
activity, attentional focus, specific postures) and the
mechanisms by which they produce clinical benefits (44).
Iyengar yoga practice places a great deal of emphasis on
‘opening the chest’ as in the case of certain poses such as
backbends, which may have direct effects on the
circulation that may elevate mood and psychological
well-being (8).
A limitation of this study is the single-group outcome
design with no placebo or other controls. As with many
unblinded interventional studies, it is possible that the
observed benefits in the present study may be related to
other factors unrelated to our intervention, such as
participation in a therapeutic program and expectations
of benefit; of note, we found that the participants’
expectations assessed at intake were not correlated with
symptomatic outcome. Regular participation in a social
group is another such non-specific factor. No limitations
were placed on socializing either immediately before or
after each session or at other times. Future studies may
incorporate explicit controls for this factor and should
gather data on how much socializing took place and how
it affects outcome. It is noteworthy that studies employing Iyengar yoga interventions for other conditions
(cancer survivors, self-reported emotional distress)
found beneficial effects for depression and mood as
well as anxiety and physical well-being (45–47). These
studies included control conditions.
Our remission rate of 65% compares favorably with
other CAM intervention studies: 43% using SAMe as an
augmenter to anti-depressants (48); 20% using omega-3
fatty acid (49); 19% using folinic acid (50). Coppen and
499
Bailey (51) added folic acid or placebo to fluoxetine, and
found that 65% (folate) versus 48% (placebo) met
‘recovery’ criteria using a more liberal standard for
remission (HAM 9) than in the present study. Using
their criterion, the remission rate in our study is 77%.
In a study of the effects of aerobic exercise as a
monotherapy for depression, Dunn and colleagues (52)
found a 25% remission rate.
The attrition rate of 19% is lower than that occurs in
exercise programs. Pollock (53) reported that 50% of
non-depressed individuals drop out of exercise programs
within 6 months. In the report by Dunn et al. (52), 62%
of the control condition using flexibility exercises
dropped out. Only one of the many demographic,
psychological and biological intake measures in the
present study discriminated those who attended six or
more classes from those who did not. Most of the latter
stopped attending after one or two sessions; 6 out of the
37 who enrolled in the study attended no sessions at all.
Reasons given for non-attendance were difficulties with
transportation, location of the venue, parking and traffic
congestion, even though all who were enrolled agreed to
participate after they were informed in detail about the
arrangements.
For all who completed the study, aside from clinical
symptoms of depression, reductions were also observed
in measures of anxiety, expression of anger, neurotic
symptoms, limitations on usual role activities because of
emotional difficulties, and LF-HRV. Thus, participation
in yoga did not in effect target depression only but also
affected psychological and biological processes indicative
of improved mental health in general and more effective
social behavior. LF-HRV reflects both sympathetic and
parasympathetic innervation of the heart and is an
indication of inadequate cardiac parasympathetic modulation (54). The reduction in LF-HRV, however,
was not coupled with an increase in HF-HRV, suggesting
inadequate
cardiac
parasympathetic
modulation.
From these findings, we may speculate that yoga practice
was beneficial in reducing stress responsivity, an effect
which is generally associated with sympathetic nervous
system activation. The pattern of HRV findings for those
who achieved remission versus those who did not may
seem counterintuitive in that it decreased in the former
and increased in the latter. Those who achieved remission
had higher levels of HRV at intake, and the observed
opposite effect may reflect the phenomenon of regression
to the mean.
We may speculate further on the reduction in HF-HRV
observed in the patients who remitted. The capacity
to suppress vagal influence appears to mediate attentional
and emotional processes that allow an organism to
optimally engage or cope with environment challenges
(15,55). Resting vagal influence and the capacity to
suppress this influence have been found to be strongly
related, but the precise distinction between these
500
Yoga as a complementary treatment of depression
Figure 1. Differences between REMISS and NON-REMISS Participants compared with data on 28 depressed and 28 matched healthy individuals
(means).
mechanisms and their concomitant behavioral processes
is not yet clearly understood. This suggests the possibility
that after yoga treatment, some patients with higher
intake resting vagal tone became actively engaged in
coping with their depression and improving their mental
health. For the patients with initial lower resting vagal
tone (non-remitters), yoga treatment may not increase
vagal tone to a level needed sufficient to improve their
condition. In these patients, it is possible that a longer
period of treatment would be beneficial, and future
experiments may explore this possibility.
We cannot exclude the possibility that a subject’s
breathing pattern may be affected by the specific yoga
practices in this intervention and that such effects may be
related to the HRV findings. Both rate and depth of
respiration affect HRV (56) and may have a general
effect on the autonomic nervous system or an effect
related to voluntary exercise efforts and that may be
independent of vagal control of the heart. The latter may
determine phasic respiration- but not tonic vagus-related
changes in HF-HRV. One might see reductions in
respiration rate associated with the focus on breathing
in yoga practice, which would likely show up in increased
HF-HRV, which was not the case for remitters.
Further investigation is warranted on the effects of
respiration and of other physiological pathways of yoga
on mood and clinical condition.
The participants who remitted differed at intake
in several ways from those who did not. They had
less formal education, spent many more hours a
week in regular exercise, and had higher levels of
HF-HRV, lower levels of LF-HRV and higher BRS.
The significance of the exercise and physiological effects
is understandable and suggests that remitters were
already disposed to an activity-based treatment and that
from the standpoint of autonomic nervous system
functioning they had a greater capacity for emotional
regulation. Habitual exercise and physical activity appear
eCAM 2007;4(4)
to be beneficial for mood, depression and mental health
in general and may facilitate remission in the treatment
of depression (57,58). The finding of less education for
remitters may be in line with a greater disposition
toward an activity-based rather than an educational or
verbal therapy. In future studies, it may be advantageous
to combine meditation or other mental approaches with
the methods used in this study.
For further understanding of the differences between
remitters and non-remitters, see Fig. 1 which plots the
means for six of the eight effects in Table 2 and compares
them with the means of the same measures obtained in
28 depressed and 28 matched healthy controls
(30, discussed earlier). For these six measures, the
calculations were exactly the same and directly comparable. It can be seen that for Education (Panel F)
the NON-REMISS group had higher levels and the
REMISS group lower levels compared with the ‘norms’
for depressed and healthy people. For exercise (Panel E),
the NON-REMISS group stands out with many fewer
hours of regular exercise. As to the measures of
autonomic regulation (Panels A–D), it is apparent that
the NON-REMISS participants differed most from
the healthy group in all respects with lower BRS,
higher LF/HF, lower HF-HRV and higher HR.
It appears that exercise and education may have only
additive or secondary influences on the differences
between REMISS and NON-REMISS participants in
baseline autonomic activity. In general, these comparisons support the conclusion that the non-remitters had
reduced capacity for emotional regulation.
The mood data indicate that remitters tended to be in a
better mood throughout the study, more positive and less
negative. All participants felt better from before to after
each yoga class: more positive, less negative, and more
energetic; in fact, the non-remitters showed a greater
improvement than the remitters as their initial and
overall moods were less positive to begin with. Thus,
mood improvements associated with yoga practice
appear to be universal. How they affect depression
in any one person must depend on other individual
characteristics.
In conclusion, yoga appears to be a promising
intervention for depression. It is cost-effective and easy
to implement. Most importantly, yoga produces many
beneficial emotional, psychological, behavioral 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 the intervention. The methods and observations in
this report may help guide further clinical research on the
application of yoga in depression, with appropriate
placebo control and comparison conditions, and in
other mental health disorders, and in future research on
the processes and mechanisms involved.
501
Acknowledgements
The authors wish to acknowledge the support of the
Iyengar National Association of the US and of anonymous private donors (D.S.). Support for investigators
was also received from R01-MH069217 (I.A.C.) and
K02-MH001165 (A.F.L.). Expert instruction in Iyengar
yoga was provided by Marla Apt, James Benvenuto and
Paul Cabanis. Patricia Walden provided consultation and
guidance on the selection of yoga asanas designed for
depression. The authors would also like to thank Hana
Kim, Sonia Castillo, Vissy Kobari and Maya Belitski for
their assistance.
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Received June 5, 2006; accepted December 14, 2006