A 12-week yoga intervention results in greater improvements in mood and anxiety than equivalent walking exercise, according to a study from the USA. Previous studies have shown that yoga triggers the release of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the brain, which helps regulate neuronal activity. GABA activity is reduced in people with mood and anxiety disorders, and drugs that increase GABA activity are commonly prescribed to improve mood and decrease anxiety. In this study 34 healthy subjects were randomised to yoga or a metabolically-matched walking intervention for 60 minutes, three times a week for 12 weeks. The yoga subjects reported greater improvement in mood and a greater decrease in anxiety than the walking group, and positive correlations were found between improved mood/decreased anxiety and GABA levels in the thalamus. The yoga group demonstrated positive correlations between changes in mood scales and changes in GABA levels. (Effects of yoga versus walking on mood, anxiety, and brain GABA levels: a randomized controlled MRS study. J Altern Complement Med. 2010 Nov;16(11):1145-52).