Probing the Effect of Mindfulness Training on Glutamate/GABA Ratio and Its Association with Dopamine Availability: A Preliminary Single-arm Pilot Study

Objective: Mindfulness is an effective non-pharmacological intervention for mental health.However, little is known about the underlying neurological mechanisms involved, especially glutamate, -aminobutyric acid (GABA), and the excitation-inhibition (E-I) balance.This study examined changes in these markers after mindfulness training and whether these changes are related to the baseline dopamine transporter (DAT) availability.We also probed the associations with outcome markers of mindfulness-based stress reduction (MBSR) training.Methods: In this single-arm pilot study, 11 participants with Graves' disease were enrolled and received MBSR training.Single-photon emission computed tomography study using [99mTc]TRODAT-1 was employed to assess DAT availability before the intervention, and 1 H magnetic resonance spectroscopy was used to assess the concentrations of glutamate, GABA, and the E-I balance.Attention and heart rate variability (HRV) were also measured before/after MBSR training.Results: An elevated E-I balance and reduced GABA concentration after MBSR training were found.A lower baseline DAT availability was associated with a greater increase in glutamate and a greater increase in the E-I balance.A greater E-I balance after training was related to a greater frequency of HRV and better attention performance after the intervention.Conclusion: The findings are novel.An elevated E-I balance could be the short-term effect of MBSR training, and this effect was greater among participants with a lower level of DAT availability at baseline.This finding may imply that excitation-related processes, such as neuroplasticity, could be the overlooked mechanism of mindfulness training.