LOS ANGELES -- Southern California scientists report that they have developed the first test that appears to be able to detect Alzheimer's disease in its early stages.
Such early diagnosis would allow prospective Alzheimer's victims to plan their future care and make arrangements for their families while still in control of their mental faculties.
In the longer term, when new drugs for Alzheimer's become available, such diagnosis might make it possible to treat victims at the beginning of the debilitating disease when chances of success are higher.
Currently, it is difficult to diagnose Alzheimer's, which affects as many as 4 million Americans. Physicians typically identify it by eliminating all other possibilities, but in doing so misdiagnose 10 percent to 20 percent of patients, according to the Alzheimer's Association. The disorder can be confirmed definitively only by examining the brain in an autopsy.
Researchers at SIBIA Inc., a San Diego-based biotechnology offshoot of the Salk Institute, report their success in using the new test on an Indiana family with hereditary Alzheimer's disease. The researchers wrote in yesterday's issue of the Lancet that the new test correctly identified members of the family who carry a gene that produces the disorder.
Even more promising, the test was able to show that one family member with no apparent symptoms was actually developing the disease. A subsequent neurological examination confirmed that diagnosis.
Successful studies with the test in about 100 human patients have so far been reported by researchers using the SIBIA test. The Lancet study reported yesterday is particularly significant, even though it covers only six people, because of what it shows about the ability of the test to chart the progress of the disease, said biochemist Steven L. Wagner of SIBIA.
Studies on much larger numbers of patients are now in progress at Alzheimer's centers around the country. If those results are as successful as the preliminary studies, the company will begin marketing the test next year, Mr. Wagner said.
While larger numbers of patients will have to be studied, the new test looks promising, according to Dr. Creighton Phelps, a neurologist at the National Institute of Aging in Bethesda, Md. "An earlier diagnostic test will be very useful as we develop treatments that might slow down the course of the disease . . . If we could just delay the onset of the disease by even five years, the quality of the patient's life would be much enhanced."