Effects of age and sex on the concentrations of glutamate and glutamine in the human brain

PURPOSE: To determine the effects of age and sex on cerebral glutamate and glutamine concentrations in a large sample of healthy humans using a dedicated measuring and evaluation procedure. Exploratory examinations of other brain metabolites were also conducted.

MATERIALS AND METHODS: In 118 healthy subjects aged 19 to 55 years (59 female) absolute concentrations of glutamate, glutamine, N-acetylaspartate (NAA), total creatine, and total choline (tCho) in voxels comprising the left hippocampus (HC) and the anterior cingulate cortex (ACC) were investigated using point-resolved spectroscopy with an echo time of 80 ms at 3 Tesla in combination with a reliable quantification procedure. Special care was taken to correct for multiple comparisons.

RESULTS: An age-related decline of the concentrations of glutamate in both regions studied was observed whereas glutamine levels in ACC increased with age. Statistically significant sex-related differences were detected for glutamate in the HC and for tCho in the ACC. NAA decreased with age in both regions, the significance not surviving Bonferroni correction.

CONCLUSION: The results demonstrate effects of age and gender on glutamate, glutamine, choline containing compounds, and NAA in healthy human brain. They add to the growing evidence for gender-specific differences in cerebral neurotransmission, metabolism, and structure across the lifespan.