Levels of phospholipid catabolic intermediates, glycerophosphocholine and glycerophosphoethanolamine, are elevated in brains of Alzheimer's disease but not of Down's syndrome patients.

Concentrations of glycerophosphocholine and of glycerophosphoethanolamine, the metabolites of two major membrane phospholipid classes, phosphatidylcholine and phosphatidylethanolamine respectively, were determined post-mortem in cortical areas 20 and 40 and in cerebellum and caudate nucleus of brains obtained at autopsy from patients with Alzheimer's disease, Down's syndrome and age-matched control subjects. Glycerophosphocholine concentrations in all of the brain regions examined were higher by 67-150% in Alzheimer's disease than in control brains and 81-104% higher in Alzheimer's disease than in Down's syndrome. Glycerophosphoethanolamine concentrations were 21-52% higher in Alzheimer's disease than in controls, and 27-92% higher in Alzheimer's disease than Down's syndrome. Levels of glycerophosphocholine and of glycerophosphoethanolamine did not differ significantly between Down's syndrome and control brains. These data indicate that abnormal phospholipid metabolism in brain is characteristic of Alzheimer's disease but not Down's syndrome and suggest that this abnormality may be a central pathophysiological feature of Alzheimer's disease because levels of glycerophosphocholine and of glycerophosphoethanolamine are elevated in brain regions with and without manifestations of histopathology.