HEALTH -- August 10, 2010 at 6:40 PM EDT
Spinal Fluid Test a New Tool for Diagnosing Alzheimer's Disease
Doctors may be able to reliably predict a person's chance of developing Alzheimer's disease from a simple analysis of their cerebral spinal fluid, according to a study released Monday.
The study, published in the journal Archives of Neurology, analyzed three biomarkers in the spinal fluid of more than 400 older adults. Of those studied, 114 had no cognitive problems, 200 had mild memory problems and 102 had been diagnosed with Alzheimer's Disease.
Results showed that of the study group, more than 90 percent of Alzheimer's patients, 72 percent of those who had only mild memory impairment and 36 percent of those with no symptoms at all had Alzheimer's-level proteins in their spinal fluid.
In a separate study, the spinal test detected the signature proteins in 57 people with mild memory loss. All of those patients went on to develop the disease within five years.
"Until recently, diagnosis of Alzheimer's Disease could not be made with confidence until an autopsy after death," said Dr. Paul Aisen, professor and Alzheimer's researcher at the University of California, San Diego. "Now we have these tools based on the analysis of cerebral spinal fluid that allow us to have a lot of confidence in the diagnosis of patients."
The spinal tests are designed to detect the tau and amyloid beta proteins in the cerebral spinal fluid, both indicators of Alzheimer's, and believed to cause the insidious plaques and tangles that are characteristic in the brains of people with the disease. Patients with Alzheimer's have elevated levels of tau and lower-than-normal levels of amyloid beta; these brain changes may begin more than a decade before the first symptoms of memory loss.
"We currently have a symptomatic treatment for Alzheimer's Disease, which is like taking an aspirin for pneumonia instead of an antibiotic."
Dr. John Trojanowski, University of Pennsylvania
There is no cure for Alzheimer's, but Dr. John Trojanowski, a University of Pennsylvania researcher and senior author of the study, hopes this test will be a useful tool to scientists working to develop treatments that slow the progress of the disease.
"We currently have a symptomatic treatment for Alzheimer's Disease, which is like taking an aspirin for pneumonia instead of an antibiotic," he said. "That will make you feel better, but it doesn't cure the progress. We're studying therapies to slow the disease, and our hope is these biomarkers will accelerate the pace of those clinical trials."
In an Archives of Neurology editorial that accompanied the report, doctors said the spinal tests could one day become a routine screening tool.
But Aisen, professor and Alzheimer's researcher at the University of California, San Diego, cautioned against widespread use of the test now, saying such early detection can be dangerous with such limited options for treatment.
"We'd be telling patients that they have abnormalities associated with Alzheimer's Disease, without being able to tell them precisely what to expect in the years to come, and without being able to treat them or to intervene," Aisen said.
But, he said, the test could prove "enormously important" for research, adding that animal studies have already indicated that treatment administered at the earliest stages of the disease may be more effective than later stage treatment.