Movement-based yoga appears to ease depressive symptoms in a wide range of mental health disorders, a new systematic review and meta-analysis suggest.
Results of the research, which included 19 studies and more than 1,000 patients with a variety of mental health diagnoses, showed that those who practiced yoga experienced greater reductions in depressive symptoms versus those undergoing no treatment, usual treatment, or attention-control exercises. In addition, there was a dose-dependent effect such that more weekly yoga sessions were associated with the greatest reduction in depressive symptoms.
“Once we reviewed all the existing science about the mental health benefits of movement-based yoga, we found that movement-based yoga – which is the same thing as postural yoga or asana – helped reduce symptoms of depression,” study investigator Jacinta Brinsley, BClinExPhys, of the University of South Australia, Adelaide, said in an interview.
“We also found those who practiced more frequently had bigger reductions. However, it didn’t matter how long the individual sessions were; what mattered was how many times per week people practiced,” she added.
The researchers noted that the study is the first to focus specifically on movement-based yoga.
“We excluded meditative forms of yoga, which have often been included in previous reviews, yielding mixed findings. The other thing we’ve done a bit differently is pool all the different diagnoses together and then look at depressive symptoms across them,” said Ms. Brinsley.
The study was published online May 18 in the British Journal of Sports Medicine.
Getting clarity
Depressive disorders are currently the world’s leading cause of disability, affecting more than 340 million people.
Most individuals who suffer from depressive disorders also experience a host of physical comorbidities including obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease.
Perhaps not surprisingly, physical inactivity is also associated with higher levels of depressive symptoms, which may be the reason some international organizations now recommend that physical activity be included as part of routine psychiatric care.
One potential form of exercise is yoga, which has become popular in Western culture, including among psychiatric patients. Although previous systematic reviews and meta-analyses have examined the effects of various yoga interventions on mental health, none has investigated the benefits of yoga across a range of psychiatric diagnoses.
What’s more, the authors of these reviews all urge caution when interpreting their results because of potential heterogeneity of the various yoga interventions, as well as poor methodological reporting.
“As an exercise physiologist, I prescribe evidence-based treatment,” said Ms. Brinsley. “I was interested in seeing if there’s evidence to support movement-based yoga in people who were struggling with mental health or who had a diagnosed mental illness.
“The [previous] findings are quite contradictory and there’s not a clear outcome in terms of intervention results, so we pooled the data and ran the meta-analysis, thinking it would be a great way to add some important evidence to the science,” she added.
To allow for a more comprehensive assessment of yoga’s potential mental health benefits, the investigators included a range of mental health diagnoses.
Dose-dependent effect
Studies were only included in the analysis if they were randomized, controlled trials with a yoga intervention that had a minimum of 50% physical activity during each session in adults with a recognized diagnosed mental disorder. Control conditions were defined as treatment as usual, wait list, or attention controls.
Two investigators independently scanned article titles and abstracts, and a final list of articles for the study was decided by consensus. Study quality was reported using the PEDro checklist; a random-effects meta-analysis was conducted using Comprehensive Meta-Analysis software.
A total of 3,880 records were identified and screened. The investigators assessed full-text versions of 80 articles, 19 of which (1,080 patients) were eligible for inclusion in the review.
Of these, nine studies included patients with a depressive disorder; five trials were in patients with a diagnosis of schizophrenia, three studies included patients with a diagnosis of PTSD, one study included patients diagnosed with alcohol dependence, and one study included patients with a range of psychiatric disorders.
Of the 1,080 patients included in the review, 578 were assigned to yoga and 502 to control conditions. Yoga practice involved a mixture of movement, breathing exercises, and/or mindfulness, but the movement component took up more than half of each session.
The yoga interventions lasted an average of 2.4 months (range, 1.5-2.5 months), with an average of 1.6 sessions per week (range, 1-3 sessions) that lasted an average of 60 minutes (range, 20-90 minutes).
Of the 19 studies (632 patients), 13 reported changes in depressive symptoms and were therefore included in the meta-analysis. The six studies excluded from the quantitative analysis did not report depression symptom scores.
With respect to primary outcomes, individuals who performed yoga showed a greater reduction in depressive symptoms, compared with the three control groups (standardized mean difference, –0.41; 95% CI, –0.65 to –0.17; P < .001).
Specific subgroup analyses showed a moderate effect of yoga on depressive symptoms, compared with wait-list controls (SMD, –0.58; P < .05), treatment as usual (SMD, –0.39; P = .31), and attention controls (SMD, –0.21; P = .22).
Subgroup analyses were also performed with respect to diagnostic category. These data showed a moderate effect of yoga on depressive symptoms in depressive disorders (SMD, –0.40; P < .01), no effect in PTSD (SMD, –0.01; P = .95), a nominal effect in alcohol use disorders (SMD, –0.24; P = .69), and a marked effect in schizophrenia (SMD, –0.90; P < .01).
Movement may be key
Researchers also performed a series of meta-regression analyses, which showed that the number of yoga sessions performed each week had a significant effect on depressive symptoms. Indeed, individuals with higher session frequencies demonstrated a greater improvement in symptoms (beta, –0.44; P < .001).
These findings, said Ms. Brinsley, suggest yoga may be a viable intervention for managing depressive symptoms in patients with a variety of mental disorders.
Based on these findings, along with other conventional forms of exercise.
Equally important was the finding that the number of weekly yoga sessions moderated the effect of depressive symptoms, as it may inform the future design of yoga interventions in patients with mental disorders.
With this in mind, the researchers recommended that such interventions should aim to increase the frequency or weekly sessions rather than the duration of each individual session or the overall duration of the intervention.
However, said Ms. Brinsley, these findings suggest it is the physical aspect of the yoga practice that may be key.
“Yoga comprises several different components, including the movement postures, the breathing component, and the mindfulness or meditative component, but in this meta-analysis we looked specifically at yoga that was at least 50% movement based. So it might have also included mindfulness and breathing, but it had to have the movement,” she said.