Motor cortex glutathione deficit in ALS measured in vivo with the J-editing technique

This study compared in vivo levels of the antioxidant glutathione (GSH) in the motor cortex of 11 ALS patients with those in 11 age-matched healthy volunteers (HV). Using the standard J-edited spin-echo difference MRS technique, GSH spectra were recorded on a 3.0 T GE MR system from a single precentral gyrus voxel. GSH levels expressed as ratios to the unsuppressed voxel tissue water (W) were 31% lower in ALS patients than in HV (p=.005), and 36% lower in ALS than in HV (p=.02) when expressed as ratios to the total creatine peak (tCr), supporting a role for oxidative stress in ALS. Levels of the putative neuronal marker N-acetylaspartate (NAA) relative to W did not differ between ALS and HV (p=.26), but were lower by 9% in ALS than in HV (p=.013) when expressed as ratios relative to tCr. This discrepancy is attributed to small but opposite changes in NAA and tCr in ALS that, as a ratio, resulted in a statistically significant group difference, further suggesting caution in using tCr as an internal reference under pathological conditions.