|November 25, 2003
A high-tech x-ray technique called magnetic resonance imaging, or MRI, shows promise for detecting Alzheimer's disease at an early stage, even before symptoms appear, doctors at New York University report.
The researchers followed 45 healthy men and women over age 60 for six years. All were mentally intact at the start of the study. Each participant received an MRI brain scan at the start of the study, then again after two years. By the end of the study, 13 people had developed memory problems.
Those who developed symptoms of Alzheimer's disease showed shrinkage in two areas of the brain: the hippocampus, a seashorse-shaped area essential for memory, and another brain area important for thought called the entorhinal cortex.
The technique was about 90 percent accurate in identifying cognitive decline, meaning that it detected nine out of ten people who later suffered from memory loss. It also identified 90 percent of those whose memories remained normally intact for their age.
Although these results are encouraging, MRI and other diagnostic techniques will need additional study before they become a standard part of Alzheimer's care. "It will be important to compare the volumes of various brain structures in other dementias, such as Pick's disease, in order to determine whether hippocampal shrinkage is specific for Alzheimer's," says Samuel E. Gandy, M.D., Ph.D., chairman of the scientific advisory board of the Fisher Center for Alzheimer's Research Foundation. The results from the current report are just one more step in the search for an effective diagnostic tool for early Alzheimer's.
Improving the early diagnosis of Alzheimer's disease is a key goal of much research. Many of the drugs currently offered, as well as others in the pipeline, work best when given in the earlier stages of the disease. An early diagnosis also provides persons with Alzheimer's and those who care for them time to pursue options for treatment and care while the patient can still participate in making decisions.
Scientists had earlier shown that high-tech diagnostic techniques that image the brain, such as MRI and PET scans, can reveal structural and metabolic changes in the brain that appear to signal early losses in memory and thinking skills. Shrinkage of the hippocampus, for example, may sometimes be a sign of mild cognitive impairment (MCI), a less severe form of memory loss that may progress to Alzheimer's.
In addition to these imaging techniques, researchers have been investigating blood and lab tests that may provide an early clue to the diagnosis of Alzheimer's. So far, however, no diagnostic test can accurately pinpoint a diagnosis with a high degree of certainty. In some cases, a definitive diagnosis cannot be made until an autopsy is done when a person dies.
The study appeared in the December issue of Radiology, a medical journal for physicians.
For more on the diagnosis of Alzheimer's disease, visit www.ALZinfo.org.
By www.ALZinfo.org, The Alzheimer's Information Site. Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer's Research Foundation.