MRS in relation to hippocampal volume in the oldest old.

The MRS brain metabolite ratio N-acetylaspartate (NAA)/myo-inositol (mI) is reported to be decreased in AD. MRS was used to study medial temporal and parietal regions in 60 cognitively healthy subjects older than 85 years. Subjects with small hippocampal volumes, a putative risk factor for dementia, had significantly lower NAA/mI in parietal and temporal lobes compared with other subjects. Neuropsychological tests and APOE genotype did not correlate with MRS ratios. MRS measures are candidate biomarkers for dementia risk.