This blog entry is the second in a series which is examining the mental health benefits of yoga. Last month I blogged about yoga for psychiatric disorders, and today I shall be looking specifically at the benefits for schizophrenia.
The benefits of exercise and physical activity for schizophrenia are increasingly being recognised. Regular exercise can help some individuals with schizophrenia improve both their physical and mental health and well-being (Gorczynski and Faulkner, 2010). Moreover, exercise has been shown to alleviate secondary symptoms of schizophrenia such as depression, low self-esteem and social withdrawal (Faulkner, 2005).
A number of studies have observed the effect of yoga amongst individuals with schizophrenia. In January 2013 a systematic review and meta-analysis was published in BMC Psychiatry which assessed the following question: can yoga be effective in patients with schizophrenia?
A range of databases were searched to identify randomised controlled trials (RCTs) and randomised cross-over trials (data extracted from first treatment phase only) of patients with schizophrenia where yoga was compared to either usual care or non-pharmalogical interventions.
- Primary outcomes of interest were clinical symptoms and quality of life.
- The abstracts of 109 identified studies were screened independently by two authors in accordance with pre-specified inclusion criteria.
- Additionally, the reference lists of identified studies were searched for relevant publications.
- Studies eligible for meta-analyses had data extracted independently by two authors.
- Risk of bias was independently assessed by two authors, using the Cochrane Risk of Bias Tool.
Appropriately, separate meta-analyses were conducted for short and long-term effects as well as for different control interventions. Meta-analyses used a random effects model.
Standardised mean differences (SMD) and 95% confidence intervals (CI) were reported. SMD is the difference in group means divided by the pooled standard deviation.
Five studies were eligible for inclusion in the systematic review. One study had insufficient raw data therefore 4 studies were eligible for meta-analyses. Risk of bias was reported to be low in 2 studies, and high in 3 studies. Of note, attrition (drop-out) bias was high across all studies.
Meta-analyses revealed the following:
- No evidence found for short-term effects of yoga compared to usual care for positive symptoms (SMD = -0.58; 95% CI -1.52 to 0.37) or negative symptoms (SMD = -0.59; 95% CI -1.87 to 0.69)
- No evidence found for short-term effects of yoga compared to exercise for positive symptoms (SMD = 0.35; 95% CI -0.75 to 0.05) or negative symptoms (SMD = 0.28; 95% CI -1.42 to 0.86)
- Moderate evidence for short-term effects on quality of life compared to usual care (SMD = 2.28; 95% CI 0.42 to 4.41), however these effects were only present in studies with a high risk of bias
Fewer that 10 studies were included in the meta-analyses; therefore the authors were unable to analyse funnel plots for publication bias.
This systematic review found moderate evidence for short-term improvements of quality of life in schizophrenia patients after yoga interventions. Only limited evidence was found for symptom relief and this evidence was based on only 1 study with unclear diagnostic method and short yoga intervention. No evidence was found for improved function.
The authors concluded that no recommendation could be made for yoga as a routine interventiuon for schizophrenia patients based on the current available evidence. To be clear, that’s not to say there are no benefits – but that we do not have adequate evidence of benefits for people with schizophrenia at present.
This study was well conducted, however there were some notable limitations:
- It is suprising that the authors did not report searching for studies using a clinical trials register (e.g. ICTRP). Although trial registration is not yet mandatory, it is good practice, and many journals will not publish trial results unless the trial was registered. The benefit of searching for studies using a trial register is that it allows identification of all trials conducted, irrespective of whether or not they were published. As such, searching registers can help to reduce publication bias.
- The inability of the authors to assess publication bias is problematic – particularly as the studies identified reported high attribution bias. Not accounting for publication and attribution bias means the effect sizes reported (e.g. moderate improvements for quality of life improvements) may be an over-estimation of the reality.
This systematic review and meta-analysis suggests that there is not enough evidence to judge the effectiveness of yoga as an intervention for people with schizophrenia. Available medications prescribed for schizophrenia are reported to have a limited impact on negative symtoms (such as flat moods, social withdrawal and low motivation); therefore its important to explore if and how specific exercise interventions (such as yoga) can benefit people with schizophrenia.
However these benefits will need to be assessed through future studies employing rigorous methodology, adequate sample sizes (especially as most studies report high drop-out rates), and clear reporting of findings. Here at Mental Elf we are excited about the potential benefits that yoga can bring to mental health – and hope that future studies can address current limitations, and report more robust evidence in the future.
Cramer H, Lauche R, Klose P, Langhorst J and Dobos G. Yoga for schizophrenia: a systematic review and meta-analysis, BMC Psychiatry 2013, 13:32
Gorczynski P, Faulkner G. Exercise therapy for schizophrenia. Cochrane Database of Systematic Reviews 2010, Issue 5. Art. No.: CD004412. DOI: 10.1002/14651858.CD004412.pub2.
Faulkner G. Exercise as an adjunct treatment for schizophrenia. In: Faulkner G, Taylor A editor(s). Exercise, Health, and Mental Health: Emerging Relationships. London, UK: Routledge, 2005:27–47. [Amazon link]