Extant data from in vivo animal models and postmortem studies indicate that Alzheimer’s disease pathology is associated with reduction of the brain antioxidant glutathione , yet direct clinical evidence has been lacking. In this study, we investigated GSH modulation in the brain with AD and assessed the diagnostic potential of GSH estimation in hippocampi and frontal cortices as a biomarker for AD and its prodromal stage, mild cognitive impairment .