In vitro 31P NMR spectroscopy detects altered phospholipid metabolism in Alzheimer's disease

In order to study possible metabolic derangements in Alzheimer's disease (AD), we performed phosphorus 31 nuclear magnetic resonance (31P NMR) spectroscopy on brain samples obtained at autopsy from 7 patients with AD and 9 control subjects. Aqueous solutions of brain tissue contained well-defined peaks of intermediate compounds in phospholipid metabolism, including the phosphomonoesters phosphocholine and phosphoethanolamine, and the phosphodiesters glycerophosphorylcholine and glycerophosphorylethanolamine. 31P NMR spectra also displayed the inorganic phosphorus signal, which provides an index to the in vivo concentration of high-energy compounds. We found evidence for altered phospholipid metabolism in that relative levels of phosphomonoesters were decreased, and phosphodiesters increased, in frontal and parietal regions of patients with AD compared to control subjects. The inorganic phosphorus resonance peaks were similar in AD and control subjects, suggesting that energy stores are not diminished in AD. These preliminary data are consistent with the hypothesis that abnormalities in phospholipid metabolism contribute to possible neuronal membrane dysfunction and impaired cholinergic neurotransmission in AD.