A 2012 study identified significant differences in gray matter volume and self-reported cognitive failures between hatha yoga practitioners and a sample of well-matched controls such that yoga practitioners exhibited volumetrically larger brain structures and fewer lapses in executive function in daily life[1]. 

Structural differences were particularly evident in brain regions subserving higher-order control of cognitive and motor responses.

Concomitantly, the extent to which the yoga and control group differed with regard to gray matter volume in these regions was significantly associated with the occurrence of self-reported cognitive failures.

Moreover, yoga experience was significantly predictive of gray matter volume in many of these same neuroanatomical regions. 

Taken together, study findings suggest that the practice of hatha yoga (a multimodal discipline involving physical postures, breathing exercises, and meditation) is associated with enhanced cognitive function coupled with enlargement of brain structures held to instantiate executive control.

The study suggests that yoga practice may serve as an effective treatment intervention for disorders with concomitant grey matter volume atrophy and cognitive difficulties. 

For example, results from the current study may be meaningfully contrasted with extant literature demonstrating that grey matter atrophy is associated with a broad array of psychiatric conditions including:

- Depression [2]
- Age-related mild cognitive impairment and depression [3]
- Posttraumatic stress disorder [4, 5]
- Chronic pain [6]

Proposed mechanism:

Hatha yoga techniques, including physical postures (asanas), breathing exercises (pranayama), and meditation, involve the practice of mindfulness, that is, repeated placement of attention onto an object while alternately acknowledging and letting go of distracting thoughts and emotions. In the case of yoga, the object of mindfulness practice might include proprioceptive or interoceptive sensations stemming from physical posture or respiration.

A number of studies link mindfulness with enhanced cognitive function and brain plasticity (for reviews see [7, 8]). For example, mindfulness practice has been shown to promote attentional regulation [9] and increased executive control of automatic responses [10]. 


References:

1. Brett Froeliger, Eric L. Garland, and F. Joseph McClernon, “Yoga Meditation Practitioners Exhibit Greater Gray Matter Volume and Fewer Reported Cognitive Failures: Results of a Preliminary Voxel-Based Morphometric Analysis,” Evidence-Based Complementary and Alternative Medicine, vol. 2012, Article ID 821307, 8 pages,2012.doi:10.1155/2012/821307

2. M.-Y. Du, Q.-Z. Wu, Q. Yue et al., “Voxelwise meta-analysis of gray matter reduction in major depressive disorder,” Progress in Neuro-Psychopharmacology and Biological Psychiatry, vol. 36, no. 1, pp. 11–16, 2012.

3. C. Xie, W. Li, G. Chen et al., “The co-existence of geriatric depression and amnestic mild cognitive impairment detrimentally affect gray matter volumes: Voxel-based morphometry study,” Behavioural Brain Research, vol. 235, no. 2, pp. 244–250, 2012. 

4. M. Tavanti, M. Battaglini, F. Borgogni et al., “Evidence of diffuse damage in frontal and occipital cortex in the brain of patients with post-traumatic stress disorder,” Neurological Sciences, vol. 33, pp. 59–68, 2011. 

5. S. H. Woodward, M. Schaer, D. G. Kaloupek, L. Cediel, and S. Eliez, “Smaller global and regional cortical volume in combat-related posttraumatic stress disorder,” Archives of General Psychiatry, vol. 66, no. 12, pp. 1373–1382, 2009. 

6. P. Y. Geha, M. N. Baliki, R. N. Harden, W. R. Bauer, T. B. Parrish, and A. V. Apkarian, “The brain in chronic CRPS pain: abnormal gray-white matter interactions in emotional and autonomic regions,”Neuron, vol. 60, no. 4, pp. 570–581, 2008. 

7. A. Chiesa, R. Calati, and A. Serretti, “Does mindfulness training improve cognitive abilities? A systematic review of neuropsychological findings,” Clinical Psychology Review, vol. 31, no. 3, pp. 449–464, 2011. 

8. H. A. Slagter, R. J. Davidson, and A. Lutz, “Mental training as a tool in the neuroscientific study of brain and cognitive plasticity,” Frontiers in Human Neuroscience, vol. 7, 17 pages, 2011. 

9. A. Lutz, H. A. Slagter, J. D. Dunne, and R. J. Davidson, “Attention regulation and monitoring in meditation,” Trends in Cognitive Sciences, vol. 12, no. 4, pp. 163–169, 2008. 

10. J. Greenberg, K. Reiner, and N. Meiran, ““Mind the trap”: mindfulness practice reduces cognitive rigidity,” PloS one, vol. 7, no. 5, Article ID e36206, 2012.