Brown, G.G., Levine, S.R., Gorell, J.M., Pettegrew, J.W., Gdowski, J.W., Bueri, J.A., Helpern, J.A., and Welch, K.M.A.
Although experts disagree on how often Alzheimer's disease (AD) and multiple-infarct dementia (MID) are accurately diagnosed, there is agreement that the diagnoses are difficult and perfect accuracy is not yet attainable. While AD results from biochemical and structural changes within neurons, MID results from ischemic damage to many small areas of the brain where blood flow has been inadequate. For patients with MID, treatment of the risk factors associated with stroke may prevent further deterioration; the deterioration of AD is inexorable. To help distinguish between AD and MID, it would be helpful to be able to examine the biochemical workings of the brain directly. While this is clearly not practical, the NMR, or nuclear magnetic resonance spectroscope, may be of some service. The NMR examines the behavior of atomic nuclei in a magnetic field; for atoms present in large enough quantities, such as phosphorous, the NMR can distinguish properties of the magnetic ''neighborhood'' the phosphorus atom exists in, and can thus provide information about relative quantities of different chemical forms which include the element. This method was used to distinguish the ratio of phosphocreatine to inorganic phosphate and the ratio of phosphomonoesters to phosphodiesters in the brains of both Alzheimer's patients and patients with multiple-infarct dementia. The ratio of phosphocreatine to inorganic phosphate proved to be elevated in both the temporoparietal region and frontal region of the brain in patients with MID. When used as a differentiating characteristic, this ratio was able to correctly distinguish all 10 test cases of MID from 16 of 17 cases of probable Alzheimer's. Similarly, both phosphomonoesters and the ration of phosphomonoesters to phosphodiesters were elevated in the temporoparietal region of patients with Alzheimer's disease. These two metabolic parameters may prove to be valuable in distinguishing between these clinically similar but etiologically different dementing disorders. (Consumer Summary produced by Reliance Medical Information, Inc.)