Effects of age and sex on brain glutamate and other metabolites.

We previously reported the effects of sex and age on brain glutamate, as well as other brain metabolite concentrations, measured with a new technique called TE-averaged PRESS on a 3-T Siemens scanner in four brain regions of 50 healthy subjects. While revising the original IDL processing script for a scanner upgrade, we noted a programming error in the original code that did not use the unsuppressed water signal corrected for T2 decay and percentage of cerebrospinal fluid to calculate the metabolite concentrations. We report here the reanalyzed metabolite concentrations of glutamate and other metabolites that differ from our original article, based on measurements performed on the original 50 as well as the 12 new subjects (total 62 healthy subjects: 39 males and 23 females). Our reanalyzed data no longer show sex differences in brain glutamate levels in four brain regions measured, but we continue to observe significant age-related declines in glutamate, especially in the parietal gray matter and basal ganglia, and to a lesser degree in the frontal white matter. Further analyses confirm that the basal ganglia and frontal white matter glutamate declines were predominantly due to a decline in men, but not women. These findings indicate that brain glutamate concentrations decline markedly with age, and may be especially useful as a marker for brain diseases that are affected by aging.