1H-MR spectroscopy (MRS) is a well-established tool to provide in vivo measurement of gamma-aminobutyric acid (GABA), glutamine and glutamine (Glx) concentrations for a variety of conditions1. There is an increasing interest in using spectral editing methods to measure GABA and Glx in the human brain. The commonly used GABA-editing sequence MEGA-PRESS provides filtered GABA signals based on the molecule’s J-coupling2, 3. Nonetheless, quantitative comparison among presently used acquisition and analysis methods is lacking. Here we compare currently available spectral fitting methods to assess the in vivo concentration values for GABA and Glx derived from edited (MEGA-PRESS) and unedited (MEGA-PRESS-OFF) spectra. We have tested our approach to assess the inter-subject variability in neurotransmitter levels arising from age effects.