J‐difference‐edited MRS measures of γ‐aminobutyric acid before and after acute caffeine administration

Purpose The aim of this study was to investigate potential effects of acute caffeine intake on J‐difference‐edited MRS measures of the primary inhibitory neurotransmitter γ‐aminobutyric acid (GABA). Methods J‐difference‐edited Mescher‐Garwood PRESS (MEGA‐PRESS) and conventional PRESS data were acquired at 3T from voxels in the anterior cingulate and occipital area of the brain in 15 healthy subjects, before and after oral intake of a 200‐mg caffeine dose. MEGA‐PRESS data were analyzed with the MATLAB‐based Gannet tool to estimate GABA+ macromolecule (GABA+) levels, while PRESS data were analyzed with LCModel to estimate levels of glutamate, glutamate+glutamine, N‐acetylaspartate, and myo‐inositol. All metabolites were quantified with respect to the internal reference compounds creatine and tissue water, and compared between the pre‐ and post‐caffeine intake condition. Results For both MRS voxels, mean GABA+ estimates did not differ before and after caffeine intake. Slightly lower estimates of myo‐inositol were observed after caffeine intake in both voxels. N‐acetylaspartate, glutamate, and glutamate+glutamine did not show significant differences between conditions. Conclusion Mean GABA+ estimates from J‐difference‐edited MRS in two different brain regions are not altered by acute oral administration of caffeine. These findings may increase subject recruitment efficiency for MRS studies.