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Imaging May Allow Early And Accurate Alzheimer's Diagnosis SAN FRANCISCO, CA -- January 27, 1998 -- A precise diagnosis of Alzheimer's disease can only be made after the progressively debilitating mental affliction claims a patient and an autopsy is performed. Tests and observations currently used to track a patient's behavioral changes and decline are still, at best, educated guesses. Now new research suggests that by using non-invasive magnetic resonance imaging (MRI), doctors can examine two alterations in the brain's hippocampus, the centre of memory and cognitive thinking and use the results to increase the likelihood of an early diagnosis of Alzheimer's. Study findings are reported in the December issue of the journal Neurology. Michael Weiner, M.D., director of the magnetic resonance unit at the San Francisco Veterans Affairs Medical Center and a professor of medicine, radiology and psychiatry at the University of California San Francisco, headed the research team. The researchers used MRI to track the presence of amino acid N-acetyl asparate (NAA), which is contained in neurons in the brain's hippocampus and whose function is unknown, and to measure the volume of hippocampal tissue. Using these two methods of evaluation together, the research team was able to correctly classify 90 percent of patients suspected of having Alzheimer's and 94 percent who did not have the disease. When used separately, neither hippocampal NAA tracking nor volume measurements could correctly classify more than 80 percent of Alzheimer's patients or 75 percent of patients in the unaffected group. The tests were conducted on a sample population of 29 patients. Twelve patients (eight women, four men ranging in age from 55 to 82) had previously been diagnosed as having mild to moderate impairment from Alzheimer's disease and 17 patients of similar age and sex had no impairment. All were recruited from the UCSF and the UC Davis Alzheimer's Centers. Weiner noted that studying the hippocampus using MRI technology is particularly encouraging because it is linked to early Alzheimer's diagnosis. Previous research using other methods to examine the size of the hippocampus to diagnose the disease had been useful only in the latter stages of the disease, when tissue atrophy is severe. "Alzheimer's is a disease in which neurons die and the glial, or supporting cells, proliferate" Weiner said. "It's like a lawn with good grass. It dies and is replaced by weeds." Weiner and his colleagues determined in their study that significant losses of NAA occurred in Alzheimer's subjects independent of the volume measurement of the hippocampus. NAA and volume were significantly lower for Alzheimer's patients compared to those without the disease. The research team cautions against using the study conclusions in clinical applications at this time because of the small population sample and the many unknowns that still exist about the disease. Weiner said a study using many more people is under way. The authors also note that because Alzheimer's patients in this study have not been followed to autopsy, it is not absolutely certain that the patients had the disease. Data from patients with dementia from other causes was not included. It is also unclear from the study findings whether the reduction in hippocampal NAA found in Alzheimer's patients was caused solely by this disease, they said. "In time, the MRI approach will lead to testing with two consequences,” he said. “First, it will allow diagnosis for Alzheimer's to eliminate uncertainty to a high degree. Second, it will allow us to track neuron loss non-invasively." Alzheimer's is the third-leading cause of death among Americans, behind cancer and heart disease. Although it is incurable and irreversible, vitamin E, indocin and post-menopausal estrogens have been suggested by others to slow progression or development of Alzheimer's according to Weiner. E-mail this page to a friend or colleague! To print, use this version