Age-related brain changes in rhesus monkeys: a magnetic resonance spectroscopic study.

Brain metabolites were measured by proton magnetic resonance spectroscopy in five young (4-10 years of age) and six old (24-30 years of age) adult rhesus monkeys. The two age groups had similar levels of N-acetylaspartate and of choline relative to creatine, but the ratio of myo-inositol/creatine was higher in each old monkey than in any of the young animals. There was no significant relationship between the metabolite ratios and cognitive performance. The findings indicate that a consistent pattern of non-invasively detectable biochemical changes occurs in the brain with ageing. Whether these changes have functional significance in age-related pathologies, or are simply markers of brain ageing will be the subject of future studies.