By combining genetic studies with sophisticated brain imaging technology, it may be possible to spot early, insidious signs of Alzheimer's disease before symptoms are obvious, doctors reported yesterday.
If the discovery can be confirmed and expanded, the researchers said, it may also aid the search for drugs that might slow or stop the disease.
"It is very exciting and promising," said Dr. Gary Small of the University of California at Los Angeles, a lead researcher on the project. "It means this strategy may eventually help identify people [with the disease] before there is permanent brain damage."
Dr. Small warned, however, that development of an accurate, early test for Alzheimer's is probably still far off. Techniques must be refined, much more research must be done and patients must be followed long enough to see if those with early signs really do get the disease.
Still, if early diagnosis does become possible, "these people would be ideal candidates for experimental treatments" for drug development, he said.
Alzheimer's is the most common type of mental disorder in the aged; in various degrees it strikes up to 10 percent of the population over age 65. As the disease progresses from simple memory loss, patients experience increasing difficulty with language and other skills.
The 16-member research team focused its study on families with two or more people who had Alzheimer's disease, selecting 40- to 90-year-old relatives who seemed normal. Of the 31 subjects studied, 12 were found to have a specific gene called APO-4 that has been associated with increased risk for Alzheimer's; 19 did not.
Then, researchers compared PET scan images of their brains. PET, or positron emission tomography, scans were also done on seven patients thought to have full-blown Alzheimer's dementia.
The results -- published in this week's issue of the Journal of the American Medical Association -- indicate that people who inherit the gene can also show early signs of reduced brain function, especially reduced glucose metabolism. Even more severe declines in glucose metabolism were seen in the brains of the Alzheimer's dementia patients.
Unfortunately, Dr. Small said, such testing "is not something we can recommend to the general public right now." The results are preliminary because the role the APO-4 gene plays in the late-onset form of Alzheimer's is not understood.