Clinical protocols have been written to use magnetic resonance spectroscopy (MRS) to examine brain myoinositol levels in healthy human subjects, and in patients with Down syndrome and Alzheimer's disease. The method employed will be 1H MRS. Whereas global brain concentrations of phosphorus metabolites have been reported by us to be unchanged in Alzheimer disease patients, the possibility that local changes occur in brain regions which demonstrate reduced glucose metabolism is being evaluated with 31P combined spectroscopic imaging.