Mental illnesses are asignificant global health concern, despite improvements in treatment modalities and access to care. The World Health Organization (WHO, 2011
) has estimated that psychiatric disorders are the leading costs of disability adjusted life years world-wide, with recent figures indicating that 37% of the loss of healthy years from non-communicable diseases is from mental illnesses. The National Co-morbidity survey replication conducted in the United States estimated the 1-year prevalence of any psychiatric disorder to be 26.2% (Kessler et al., 2008
). According to the WHO, depression ranked third among global disease burdens all over the world in 2004; it was reportedly the most important cause in middle and high income countries, while it ranked eight among the low income countries (World Health Organization, 2008
). Depression was found to result in the greatest decrement in health, compared to asthma, angina, arthritis, and diabetes (Maussavi et al., 2007
). Prevalence data for anxiety disorders, suggests that the lifetime prevalence and 12
month prevalence for any anxiety disorder are over 15 and 10%, respectively, with higher prevalence in developed countries (Kessler et al., 2009
). Likewise, schizophrenia has been associated with significantly higher health care costs, unemployment rate, and morbidity (Goeree et al., 2005
). Sleep complaints are often associated with a variety of psychiatric disorders. About 9–21% of the population has been estimated to have insomnia accompanied by serious day-time consequences which include chronic fatigue, irritability, low mood, memory impairments, and interpersonal difficulties (Moul et al., 2002
). This problem has reached epidemic proportions in the United States, where almost 25% of adults consume sleep medications at some point in a year (National Sleep Foundation, 2005
The availability of psychopharmacological treatments has increased, but the response and tolerability remain unpredictable and inconsistent. While psychotropics agents can be lifesaving for many people, there remains a considerable unmet need. The landmark National Institute of Mental health (NIMH) funded Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study showed remission in only one third of major depression patients after a trial with the first anti-depressant and worsening response rates with each subsequent trial (Trivedi et al., 2006
). The Primary Care study conducted by WHO found that 60% of the patients continued to meet criteria for depression after a year of being treated with an anti-depressant (Goldberg et al., 1998
). The Clinical Anti-psychotic Trials of Intervention Effectiveness (CATIE) demonstrated that 74% of the participants discontinued from their treatments in 18
months, with a mean time to discontinuation of 4.6
months (Lieberman et al., 2005
). Treatment resistance is a growing problem and there are millions of patients world-wide whose depression, anxiety, or schizophrenia is not fully resolved despite multiple trials of psychopharmacologic agents. Psychotropic medications are costly and suffer from significant side effects leaving patients and clinicians to struggle to balance efficacy against cost and side effects, which often leads to poor compliance and relapse.
Given the heterogeneous nature of psychiatric conditions, with respect to biological, psychological, and social factors, it is not surprising that available standard treatments often have inconsistent response rates. The quest and demand for non-pharmacological treatment modalities has been increasing (Barrows and Jacobs, 2002
). A study conducted by the Harris Interactive Service Bureau revealed that 15.8 million adults in the United States practice yoga, triple the number in 2004. The holistic goal of yoga to promote physical and mental health, and also be spiritually and socially conscious, may appeal both to consumers and providers who are concerned about the symptom reduction based focus of psychopharmacology and finding inner peace (Uebelacker et al., 2010
). The barriers to access are low and the diversity of practice styles and settings (e.g., at home versus in gyms versus outdoors) allows considerable degree of personalization. Hence, yoga appears to be a well suited intervention to test as a potential therapy for major psychiatric disorders. However, yoga has also become such a cultural phenomenon that it has become difficult for physicians and consumers to differentiate legitimate claims from hype. Our goal in this review was to examine whether the evidence matched the promise.
Yoga, with origins in ancient India has several sub-types (Table ; Cook, n.d.
), and incorporates physical postures (asanas), controlled breathing (pranayama), deep relaxation, and meditation (Javnbakht et al., 2009
). In addition to low barriers to access, the scientific rationale for yoga effects on the mind are quite strong. All yoga practices are known to influence the mental state (Telles, 2010
) – studies have noted benefits in children (Manjunath and Telles, 2004
), adults (Vialatte et al., 2008
), elderly (Krishnamurthy and Telles, 2007
), and individuals with occupational stress (Vempati and Telles, 2000
). In healthy individuals, biomarker studies suggest that yoga influences neurotransmitters, inflammation, oxidative stress, lipids, growth factors, and second messengers (Figure ), in a manner largely similar to what has been shown for anti-depressants and psychotherapy. It is hypothesized that yoga combines the effects of physical postures, which have been independently associated with mood changes (Phillips et al., 2003
), and meditation which increases the levels of Brain-derived neurotrophic factor (BDNF; Xiong and Doraiswamy, 2009
). Other effects that have been noted include increased vagal tone, increased gamma-aminobutyric acid (GABA) levels, increase in serum prolactin, downregulation of the hypothalamic-pituitary-adrenal axis and decrease in serum cortisol, and promotion of frontal electroencephalogram (EEG) alpha wave activity which improves relaxation (Janakiramaiah et al., 1998
; Kamei et al., 2000
; Streeter et al., 2007
). Lastly, prior clinical studies have noted several psychiatric conditions for which yoga has proved beneficial (Shannahoff-Khalsa et al., 1999
; Carei et al., 2010
; Visceglia and Lewis, 2011
; Katzman et al., 2012
; Libby et al., 2012
) but because of differing methods there is a need to try to synthesize such data to further the field.
Table 1 Table showing the key elements of the different forms of yoga (Cook, n.d.).
Figure 1 Schematic illustration of potential effects of yoga on biomarkers and end organs based on various sources. The strength of evidence ranges from strong to preliminary for specific effects as described further in the text. Copyright Doraiswamy and Balasubramaniam, (more ...)
Thus, while the effects of yoga on the spiritual aspects of the mind (e.g., inner peace) are well documented, its effects in major clinical psychiatric disorders are less so. The objective of this report was to systematically review the available literature for the effects of yoga on major psychiatric disorders. The focus of this review was primarily categorical disease threshold outcomes (e.g., major depression), in keeping with how psychiatric disorders are categorized and treated, and how effects of psychopharmacologic interventions are assessed – rather than on single symptom domains such as mood or sleep which cut across multiple diagnoses. We did use symptoms (e.g., depression and memory) as search terms to ensure our search was comprehensive but restricted our final review to major disorders that require intervention in practice.