Protein Test Is Step Toward Alzheimer’s Diagnosis, Scientists Say
Scientists have developed a simple test that detects a protein found in the brains of people with Alzheimer’s disease, an advance they hope will lead to the first reliable method for diagnosing the fatal, degenerative illness.
As many as 4 million Americans may suffer from Alzheimer’s disease, which progressively robs people of their memory and leads to dementia. But despite enormous efforts, no cause, cure or easy way to diagnose it has been discovered.
“This is the first real diagnostic leap,” said Garth Bissette, associate professor of psychiatry at Duke University Medical Center and a participant in the study published in today’s edition of the Journal of the American Medical Assn. “What we all have wanted is a definitive, quick, easy and accurate test. And this one fulfills the promise.”
Until now, the diagnosis of Alzheimer’s disease has relied largely on the ability of scientists to count and classify abnormal growths, called senile plaques, that appear in the brains of patients. But that method has been subjective and only certain after death. Researchers also have been forced to exclude other forms of dementia that can appear similar to that caused by Alzheimer’s disease.
Even the most sophisticated experts are correct no more than two-thirds of the time. But in the study being released today, a team from Abbott Laboratories reports that it has developed a test for a protein that seems to appear only in the tissue of people with Alzheimer’s.
The new test is not widely available for evaluating living people because it can still only be used on brain tissue and must be examined by pathologists. But researchers have found this protein in the spinal fluid as well as the brain, and they say that within a year it should be possible to test for the presence of the protein without taking tissue from the brain.
An accurate test for Alzheimer’s disease could help researchers identify those with the protein before they become sick, enabling scientists to test drugs far earlier in the course of the disease.
In the study, researchers examined the brain tissue taken from 111 subjects after death. Twenty-seven people who died without neurological disease were used for comparison, or controls; 28 subjects had neurological impairments but not Alzheimer’s disease. Tissue from the rest came from 56 former Alzheimer’s patients.
None of the 55 people who did not have Alzheimer’s disease tested positive for the protein, called Alzheimer’s Disease Associated Protein. But 48 of 56, or 86%, of those diagnosed as Alzheimer’s patients did. Of the other eight, five patients had dementia that indicated they may have had Alzheimer’s, but because of the time it took to get tissue samples after they died it could not be proved.
