IN-VIVO PROTON MAGNETIC-RESONANCE SPECTROSCOPY OF THE NORMAL AGING HUMAN BRAIN

The effect of age on brain metabolite concentrations was evaluated usi ng localized proton magnetic resonance spectroscopy. This technique al lows in vivo measurements of N-acetyl compounds (NA), total creatine ( CR), choline-containing compounds (CHO), myo-inositol (MI), glutamate and glutamine (GLX), as well as the percentage of cerebrospinal fluid (CSF) and the brain water content within the brain region studied. Fro ntal gray matter and frontal white matter brain regions were examined in 36 normal healthy volunteers (19-78 years of age). Using a rigorous absolute quantitation method, with an external reference and atrophy correction, we found relatively stable concentrations of NA, a neurona l marker. In contrast, CR, CHO, MI, and the percentage of CSF increase d in the gray matter with age. However, the brain water content decrea sed significantly with age (r=-0.72; p<0.0001). No significant age-rel ated changes in metabolite concentrations, CSF or brain water content were observed in the white matter regions. These findings demonstrate that biochemical alterations are associated with aging in the frontal gray matter. There might be an increase in the brain density as indica ted by increased metabolite concentrations and decreased brain water c ontent with aging.