Alzheimer dementia: quantification of energy metabolism and mobile phosphoesters with P-31 NMR spectroscopy

To determine whether high-energy phosphate metabolism and mobile phosphoester indexes of membrane metabolism are altered in Alzheimer disease and to help resolve some inconsistencies in the literature, brain phosphate metabolite concentrations and ratios were measured in 11 patients with mild to severe dementia of the probable Alzheimer type and 14 healthy subjects. Fully relaxed, spatially localized, phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and proton (hydrogen-1) MR imaging were performed. No significant differences were found in the concentrations and relative ratios of phosphocreatine, nucleoside triphosphate, inorganic phosphate, phosphomonoester, and phosphodiesters in whole axial sections through the lateral cerebral ventricles of the brain that could not be accounted for by atrophy. There was no correlation between P-31 NMR indexes and the severity of dementia as assessed with neuropsychologic testing. High-energy phosphate and membrane metabolism, as detected in vivo with P-31 NMR spectroscopy in whole-brain sections, do not appear to play a major role in the disease process, except as a direct consequence of atrophy quantified with H-1 MR imaging.