Yoga for psychiatric disorders: systematic review shows some benefit but more research needed

Here at Mental Elf HQ, several new pieces of research relating to yoga have come our way. This blog is the first in a series examining the mental health effects of engaging in yoga.

Yoga is a form of exercise (largely comprising physical postures and breathing) which originated in India over 5,000 years ago. Many studies have suggested that yoga is a safe and effective form of physical activity which can improve strength, flexibility and balance (NHS Choices, 2011).

The Mental Elf has previously blogged about laughter yoga and physical activity (including yog a) as a promising treatment for depression.

This blog will summarise a systematic review which was published by Frontiers in Psychiatry in January 2013. The research question was to assess whether yoga is beneficial as a treatment for major psychiatric disorders. They found that although there is some evidence from randomised control trials (RCT) supporting benefits for specific psychiatric disorders, further research is needed.

Methods

A range of databases were searched to identify RCTs where yoga was used as an intervention for a psychiatric disorder. A total of 124 studies were identified. The title and abstracts of these studies were screened according to pre-specified inclusion and exclusion criteria. Where full-text was unavailable, study authors were contacted. 16 studies met the criteria for the final review.

All authors reviewed the full-text of eligible studies. The quality of these studies were scored using two well-established guidelines (AHRQ and CEBM) and summaries of all 16 studies were reported. Evidence was grouped for different diagnoses where appropriate, and graded according to CEBM’s ‘Grades of Recommendations’ where A = recommended, B = suggested and C = may be considered.

Results

Four RCTs examined the effect of yoga on depression

Sample sizes were small; ranging between 28-70 participants per study
Yoga interventions varied in length and frequency (duration ranged from 2-24 weeks)
Each study included participants with different measures of depression (e.g. self-reported symptoms vs. validated measurement tools) and different populations (e.g. depression in alcohol dependents males vs. young adults with mild mood disturbance)
All studies were noted to have insufficient follow-up data
The authors concluded that this evidence suggested a potential acute benefit for yoga in depression (grade B evidence)

Three RCTs examined the effect of yoga on schizophrenia

Sample sizes ranged between 18 and 91 participants per study
Yoga interventions varied in length and frequency (duration ranged from 2-4 months)
One study recruited inpatients (with and without psychiatric comorbidities), one study recruited outpatients and the other study recruited both in-and-outpatients
All studies were noted to have insufficient follow-up data
The authors concluded that this evidence suggested a potential benefit for yoga alongside antipsychotic treatment for chronic schizophrenia (grade B evidence)

Two RCTs examined the effect of yoga on ADHD

Sample sizes were small; 19 children were recruited to each study
Yoga intervention varied in length and frequency (duration 20-34 weeks)
One study included children with comorbidities and variations in ADHD severity, whereas the other study had more stringent exclusion criteria
The authors concluded that this evidence suggested a potential benefit for yoga alongside pharmacotherapy for ADHD in children (grade B evidence)

Other studies examining the effect of yoga on psychiatric disorders

Two RCTs examined the effect of yoga on eating disorders; one study reported significant differences, whereas the second study reported no significant differences of yoga intervention.
Three RCTs examined the effect of yoga on sleep complaints, however these provided weak evidence of efficacy (grade C evidence)
Two RCTs examined the effect of yoga on conditions influencing cognition, however a lack of baseline measures of disease severity makes it difficult to draw conclusions from these studies.

Although many of the RCTs were reported to have statistically significant findings, neither confidence intervals nor p-values were provided in the paper. This makes it difficult to interpret both the precision of results and the likely role of chance.

Conclusion

Emerging evidence shows there may be some benefit of yoga to certain psychiatric disorders

The authors concluded:

There is emerging evidence from randomised trials to support beliefs about yoga for depression, sleep disorders and as an augmentation therapy. Limitations of literature include inability to do double-blind studies, multiplicity of comparisons within small studies, and lack of replication.

Summary

Researching the effects of yoga is not without its methodological difficulties, as the authors have noted. However, yoga continues to be a popular activity and it is important to consider the evidence behind advocated therapeutic effects.

This systematic review highlights the need for more large-scale research in this area; it is difficult to generalise findings to the general population based on small sample sizes. More robust research is needed before yoga can be recommended as a specific treatment for psychiatric conditions.

There was almost a two year delay between the identification of studies (June 2011) and publication of this paper (January 2013). As such, there may be more relevant published evidence. One thing is for sure – if we find any, we’ll be sure to blog about it and keep you informed!