Aging of the adult human brain: In vivo quantitation of metabolite contentwith proton magnetic resonance spectroscopy

The purpose of this study was to examine the effect of aging on brain metab olite concentrations, including N-acetyl aspartate [NAA], the major marker of neurones, using short echo proton spectroscopy. Single-voxel proton spec tra (TE 30 msec, TR 2 seconds) were obtained from white and gray matter usi ng automated software (PROBE, G.E., Milwaukee, WI). Spectra were analyzed u sing the variable projection technique. Thirty healthy volunteers were stud ied within the age range 24-89 years. No significant trend in change of con centrations of NAA, total creatine, total choline or myo-inositol were seen with age. The total creatine concentration of parietal white matter in the over 60 age group (6.5 +/- 0.3 mmol/l) was significantly higher than the u nder 60 age group (6.0 +/- 0.4 mmol/l; P < 0.05), No other significant diff erence between the two age groups was seen. The tissue concentration of the major neuronal marker, NAA, does not decline with age. No age-related chan ges in the concentrations of choline and myo-inositol and occipital gray ma tter total creatine were observed. These results provide a normal range of values for spectroscopically detectable metabolites within the regions stud ied, against which neurological diseases such as Alzheimer's disease can be compared in vivo. (C) 1999 Wiley-Liss, Inc.