MRI May Predict Dementia in the Healthy
Images find greater loss of brain mass is key
TUESDAY, Nov. 25, 2003 (HealthDayNews) -- Losing brain mass is a natural part of aging, but people who lose it at a high rate are at increased risk for dementia, including Alzheimer's disease, a new study says.
"With the help of MRI imaging over time, we are capable of detecting cognitive impairment, which may lead to Alzheimer's disease, before the patient shows clinical symptoms," says lead researcher Henry Rusinek, an associate professor of radiology at New York University School of Medicine.
Rusinek and his team studied 45 healthy patients, 60 years of age and older. The patients underwent MRI imaging of their medial temporal lobe at two-year intervals over six years. The medial temporal lobe is located near the middle of the brain, which includes areas critical to forming new memories.
The researchers compared images from year to year, according to the report in the December issue of Radiology. "The normal brain shrinks at a very slow rate. However we can pick up the surge in brain shrinkage in patients who were found later on to be impaired," Rusinek says.
Rusinek notes that, over time, there is an increased accumulation of cerebrospinal fluid, which indicates a loss of brain cells. By comparing the increases in fluid over time, the researchers can establish the rate of cell loss.
Over six years, 13 of the patients showed cognitive decline, the researchers report. The rate of loss of mass in the medial temporal lobe was the most significant predictor of decline, they add. The overall accuracy of this measure was 89 percent.
"This is the first study to demonstrate that these predictions can be made accurately using MRI," says co-researcher Mony J. de Leon, a professor of psychiatry and director of the Center for Brain Health at New York University School of Medicine.
Rusinek believes that measuring brain shrinkage can be used to test the effectiveness of drugs that may delay or prevent Alzheimer's. He also believes this method can be used to diagnose other types of dementia as well as Alzheimer's.
In the future, this method might be used as a screening technique to identify those at risk for Alzheimer's and other forms of dementia, Rusinek says. "But right now it's too expensive and, of course, even if we know that Alzheimer's is likely, there is no cure," he says.
De Leon says that "this is the beginning of an era of diagnosing future Alzheimer's disease in people who are within the normal limits of cognition and will put us in a position to start preventive therapy."
However, he cautions that in addition to MRIs, other tests are necessary to make a definitive diagnosis of Alzheimer's. Early diagnosis is right around the corner, but not yet here, de Leon adds.
Dr. Michael Weiner, a professor of medicine, radiology, psychiatry and neurology at the University of California at San Francisco, says the paper "demonstrates that the rate of brain shrinkage may be a useful indicator of cognitive decline, and which may predict the development of Alzheimer's disease. It's a valuable contribution to the field."
Dr. Stephen Salloway, an associate professor of clinical neurosciences neurology at Brown University, adds "this technique will be really important when we have treatments that can intervene and prevent cognitive decline. It is really very promising."