Daily aerobic exercise is a reliable and effective treatment for mild to moderate depression, but new research suggests that yoga may work even better. A study from Boston University School of Medicine showed that practicing yoga increased levels of GABA (gamma-aminobutyric) in the brain. Low levels of GABA, a neurotransmitter, are associated with depression and anxiety disorders. Investigators followed two randomized groups of healthy volunteers for 12 weeks. One group performed an hour of yoga three times a week, while the other group walked for an hour three times a week. Before and after the last session, the researchers compared the GABA levels of each of the volunteers using magnetic resonance spectroscopic imaging. They found increased GABA levels and decreased anxiety among the participants in the yoga group, who also reported a significantly greater decrease in anxiety and more improved mood over the course of the study than did the volunteers in the walking group. The study was published online by the Journal of Alternative and Complementary Medicine.