I have cut and pasted below an introduction from the results of a study published April 2012 in Acta Neuropsychiatrica. I'm posting this as sort of a placeholder on my blog, so that I can refer back to it for a good description of what yoga does to improve cognition. (Thanks to MIA for alerting me to this study.)
Adjunctive cognitive remediation for schizophrenia using yoga: an open, non-randomised trial
Bhatia, T., Agarwal, A., Shah, G., Wood, J., Richard, J., Gur, R. E., Gur, R. C., Nimgaonkar, V. L., Mazumdar, S. and Deshpande, S. N. (2012), Adjunctive cognitive remediation for schizophrenia using yoga: an open, non-randomised trial. Acta Neuropsychiatrica, 24: 91–100. doi: 10.1111/j.1601-5215.2011.00587.x
Cognitive impairment represents a prominent feature of several psychiatric illnesses, including schizophrenia (SZ), major depressive disorder (MDD) and bipolar disorder (1–3). Deficits in long-term memory, working verbal memory, executive functioning and vigilance have been consistently associated with poor functional outcome in persons with SZ (4–8). As pharmacological treatment is not routinely efficacious (9), there is ongoing interest in adjunctive non-pharmacological interventions for ameliorating cognitive deficits (10–12).
In comparison with conventional therapies, yoga represents a different approach. It is a set of mental and physical practices that have been evolving in India for several millennia. Yoga is viewed by many practitioners as a systematic process designed to purify the body and the mind from toxins accumulated due to improper lifestyle choices and negative thinking patterns. Yoga includes components centred on meditation, breathing and activity or postures designed to balance the body's ‘energy centres' (13). Intensive yoga exercises may improve the cognitive function among psychiatrically ill and healthy adults (14–20). There are several mechanisms by which the practice of yoga may improve the cognitive function. Yoga emphasises body awareness and involves focusing one's attention on breathing or specific muscles or parts of body, so yoga may improve more general as well as focused attention. Yoga practice also influences perception by increasing perceptual sensitivity, by selectively ‘shutting out' undesirable stimuli and by changing distorted perception. Practising yoga improved auditory and visual perception, by increasing sensitivity to various characteristics of the stimuli (e.g. intensity and frequency) (21). A recent study (20) observed that memory functions of male volunteers improved after yoga. In an open trial of yoga (n = 21) versus physical therapy (n = 20) among patients with SZ in India, greater improvement in psychopathology BP1 was reported with yoga therapy (YT) compared with physical therapy. Improvement in clinical severity was noted following 3 weeks of YT, but cognitive function was not evaluated (22). In another study (23), yoga was found to improve facial emotion recognition deficits. The precise physiological basis for the beneficial effects of yoga is unknown and continues to be investigated. Selvamurthy et al. (24) have found that yoga helps achieve a stable autonomic balance. Others have reported that the practice of yoga reduces autonomic arousal (25,26). Because increased physical activity reduces autonomic reactivity to mental stressors (27), it is possible that some of the beneficial effects of yoga are related to stabilisation/normalisation of autonomic function.
The studies reviewed above were conducted by highly trained therapists or clinicians in structured academic centres. Their utility in routine clinical practice is uncertain. Moreover, YT has typically not been used as a cognitive remediation strategy for individuals with impaired cognition. In the present pilot study, we evaluated the impact of YT among individuals with severe psychiatric illnesses. Cognitive domains known to be impaired in these disorders were assessed.