The 12-week yoga intervention was associated with greater improvements in mood and anxiety than a metabolically matched walking exercise. This is the first study to demonstrate that increased thalamic GABA levels are associated with improved mood and decreased anxiety. It is also the first time that a behavioral intervention (i.e., yoga postures) has been associated with a positive correlation between acute increases in thalamic GABA levels and improvements in mood and anxiety scales. Given that pharmacologic agents that increase the activity of the GABA system are prescribed to improve mood and decrease anxiety, the reported correlations are in the expected direction. The possible role of GABA in mediating the beneficial effects of yoga on mood and anxiety warrants further study.

Background The brain undergoes major remodeling during adolescence, resulting in improved cognitive control and decision-making, and reduced impulsivity, components of behavior mediated in part by the maturing frontal lobe. Gamma-amino butyric acid (GABA), the main inhibitory neurotransmitter system, also matures during adolescence, with frontal lobe GABA receptors reaching adult levels late in adolescence. Thus, the objective of this study was to characterize in vivo developmental differences in brain GABA levels. Methods Proton magnetic resonance spectroscopy (MRS) was employed at 4 Tesla to acquire metabolite data from the anterior cingulate cortex (ACC) and the parieto-occipital (POC) cortex in adolescents (n=30) and emerging adults (n=20). Results ACC GABA/Cr levels were significantly lower in adolescents relative to emerging adults, whereas no age differences were observed in the POC. Lower ACC GABA/Cr levels were significantly associated with greater impulsivity and worse response inhibition, with relationships being most pronounced for ACC GABA/Cr and No-Go response inhibition in adolescent males. Conclusions These data provide the first human developmental in vivo evidence confirming frontal lobe GABA maturation, which was linked to impulsiveness and cognitive control. These findings suggest that reduced GABA may be an important neurobiological mechanism in the immature adolescent brain, contributing to the reduced, yet rapidly developing, ability to inhibit risky behaviors and to make decisions, which could compromise adolescent health and safety.

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Objectives: The aim of this study was to compare changes in brain ␥-aminobutyric (GABA) levels associated with an acute yoga session versus a reading session. It was hypothesized that an individual yoga session would be associated with an increase in brain GABA levels. Design: This is a parallel-groups design. Settings/location: Screenings, scan acquisitions, and interventions took place at medical school-affiliated centers. Subjects: The sample comprised 8 yoga practitioners and 11 comparison subjects. Interventions: Yoga practitioners completed a 60-minute yoga session and comparison subjects completed a 60-minute reading session. Outcome measures: GABA-to-creatine ratios were measured in a 2-cm axial slab using magnetic resonance spectroscopic imaging immediately prior to and immediately after interventions. Results: There was a 27% increase in GABA levels in the yoga practitioner group after the yoga session (0.20 mmol/kg) but no change in the comparison subject group after the reading session (Ϫ0.001 mmol/kg) (t ϭ Ϫ2.99, df ϭ 7.87, p ϭ 0.018). Conclusions: These findings demonstrate that in experienced yoga practitioners, brain GABA levels increase after a session of yoga. This suggests that the practice of yoga should be explored as a treatment for disorders with low GABA levels such as depression and anxiety disorders. Future studies should compare yoga to other forms of exercise to help determine whether yoga or exercise alone can alter GABA levels.