Description of the condition
Schizophrenia is a relatively common mental disorder with a lifetime prevalence of 0.3% to 0.6% and an incidence of 10.2 to 22.0 per 100,000 person-years (McGrath 2008). It is one of the most debilitating psychiatric disorders. The Diagnostic Statistical Manual of Mental Disorders-IV (DSM-IV) criteria for schizophrenia includes positive and negative symptoms that have a detrimental impact on both social and occupational functioning (Rossler 2005). Schizophrenia accounts for 1.1% of the total disability-adjusted life years (DALYs) making it the fifth leading cause of DALYs worldwide in the 15 to 44 year-old age group (World Health Organization 2008).
Schizophrenia can have a significant impact on a person's ability to function within society due to both positive and negative symptoms The positive symptoms of schizophrenia reflect a distortion of normal functions. Acute sufferers may present with symptoms such as delusions, hallucinations and disorganised speech or behaviour. Chronic sufferers may also develop so-called negative symptoms. Negative symptoms reflect a reduction of normal functions, and include symptoms such as flattened affect, social withdrawal, impaired cognition and apathy. (Duraiswamy 2007; Rossler 2005).
After diagnosis of schizophrenia is made, antipsychotic medication is the first-line treatment. Their mechanism of action is mainly to block dopamine D2 receptors in the mesocortical and mesolimbic dopaminergic pathways. First-generation antipsychotics (e.g., chlorpromazine, fluphenazine, haloperidol) were discovered in the 1950s. They were shown to be effective in the treatment of positive symptoms, but often cause extra-pyramidal side effects (EPSE) (e.g. akathisia (restlessness), tardive dyskinesia (e.g. abnormal tongue movements, head nodding and rocking movements), parkinsonism (tremor, rigidity and bradykinesia (slowness of movement)) and acute dystonia (involuntary muscle spasms)) (Tandon 2010; Van Os 2009).
Newer agents, or second-generation antipsychotics (e.g., olanzapine, quetiapine and risperidone) less frequently cause these EPSE. Second-generation antipsychotics are associated with side effects including weight gain, sedation, sexual dysfunction and metabolic syndrome. Although equally effective in treating positive symptoms as first-generation antipsychotics, their promise of a greater efficacy against negative and cognitive symptoms has not yet been proven. Many people continue to suffer from persistent symptoms and relapses, particularly when they fail to adhere to medical treatment (Tandon 2010; Van Os 2009). This underlines the need for additional non-pharmacological interventions including psychosocial therapies as adjuncts to help alleviate symptoms, and to improve adherence, functional outcome and quality of life (Kern 2009).
Description of the intervention
Yoga originates from India as an ancient Hindu practice incorporating physical postures with breathing exercises seeking to bring about a balance between the mental and physical state (Bussing 2012; Ross 2012; Sherman 2012). The principles behind its practice were first described by Pantajali, and were believed to allow the mind and the body to be prepared for spiritual development (Ross 2012). In the western world, yoga has now been widely adopted as both a method of relaxation and exercise. Hatha yoga is the most widely adopted practice used in the Western world (Collins 1998). Its use of postures (asanas) improves strength, flexibility, co-ordination and endurance and its use of breathing exercises (pranayama) improves respiratory control and concentration. Mantra yoga is another well-known and widely practiced form of Hindu yoga and focuses on the use of chants to achieve mental and spiritual transformation (Sherman 2012). The improvements in cognition and reductions in stress seen in those who practice yoga may be of benefit to those with schizophrenia as schizophrenia is associated with cognitive defects, and relapses of schizophrenia can be associated with stress (Duraiswamy 2007).
With its increasing popularity, research into the effect of yoga on both physical and mental health has identified key benefits of yoga. It has been shown to both reduce stress and improve cognitive function in healthy people (Bangalore 2012), and has been shown to be useful as a complementary therapy for many health conditions, including an improvement in blood pressure control and mental health conditions including depression and anxiety disorders (Bussing 2012). Its benefits in other mental health conditions has lead to research into the role of yoga as a complementary therapy for the management of schizophrenia (Duraiswamy 2007). A systematic review of randomised controlled trials indicated that yoga could also be of benefit as an add-on treatment to reduce both positive and negative symptoms of schizophrenia and to improve the health-related quality of life of people with schizophrenia (Duraiswamy 2007; Vancampfort 2012).
How the intervention might work
Yoga has been identified to have a role in regulating the autonomic nervous system (Varambally 2012), decreasing sympathetic tone, creating a reaction the opposite to the 'fight or flight' reaction. There is a subsequent effect on the limbic system and hypothalamic pituitary axis leading to a reduction in blood cortisol levels. This leads to a regulation of heart rate and blood pressure, which has obvious cardiovascular benefits (Damodaran 2002). Yoga also emphasises a focus on relaxed breathing and this internal concentration is thought to reduce stress by minimising mental focus on external stressors or threats (Bangalore 2012). The decrease in cortisol levels is also thought to have an effect on the better control of blood glucose, cholesterol and total lipids. Since antipsychotic medication for the treatment of schizophrenia is associated with dyslipidaemia, diabetes and obesity, yoga may be a useful adjuvant to therapy to minimise these effects (Bangalore 2012).
The improvement in the physical health of these patients could have a direct improvement in their mental health. Yoga is also identified to have a role in improving sleep (Collins 1998). There is also thought to be a role of oxytocin, a hormone related to improved mood, analogues of which have been suggested as possible treatment of schizophrenia (Bangalore 2012; Feifel 2011). It has been reported that plasma levels of oxytocin are higher in people after practice of yoga (Varambally 2012).
In addition, yoga has been shown to have psychosocial benefits including a sense of autonomy, improved perceptions of competence, enhanced body image, self-efficacy and distraction from mental imbalance due to focuses on breathing and positions (Vancampfort 2011).
Why it is important to do this review
The practice of yoga has shown promising results in other areas for benefiting health, yet its use for people with schizophrenia is under-researched in comparison with many other physical and mental health conditions. To the best of our knowledge, there is currently no meta-analysis available assessing the effectiveness of yoga as an adjunct to standard care treatment for schizophrenia. Therefore, the aim of this review is to systematically assess and meta-analyse the effectiveness of yoga in people with schizophrenia.
In a time of increasing patient choice, this review will aim to investigate the potential benefits of yoga – if indeed there are any – and expectantly aid the integration of yoga into clinical practice.
This review will build on the work already carried out by one of the authors of this review. In a systematic review Vancampfort 2012 concluded that there is a place for yoga in add-on treatment for schizophrenia. There have been several studies comparing the effects of yoga and other forms of exercise as add-on therapies for the management of schizophrenia (Vancampfort 2011), however in this review we will focus only on comparisons of yoga with control groups consisting of standard care.