Although an estimated 5 million Americans are living with Alzheimer's, no reliable blood-based test currently exists for the neurodegenerative disorder that is the sixth-leading cause of death in the United States.
Using blood-based biomarkers -- a signature of proteins in the blood that indicate the presence of a disease -- to diagnose Alzheimer's could be a key advance, according to UCLA researchers.
"Blood-based biomarkers would have the important advantage of being safe, affordable and easy to administer in large groups or in rural areas, and therefore could have an enormous impact on clinical care and clinical trials alike,'' said Dr. Liana G. Apostolova, director of the neuroimaging laboratory at the Mary S. Easton Center for Alzheimer's Disease Research at UCLA and head of the research team.
Results of the study appeared in the journal Neurology.
Alzheimer's disease can be diagnosed definitively only by examining brain tissue after death. While people are alive, physicians must rely on proxy measures, or biomarkers, along with cognitive symptoms such as memory loss.
Two current methods for determining the beta-amyloid formation characteristic of Alzheimer's disease both have drawbacks, UCLA researchers said.
Cerebrospinal fluid can be obtained from patients, but that requires a spinal tap, an invasive procedure that carries the risk of nerve damage and other serious side effects.
Another method, the amyloid PET scan, while effective, exposes subjects to radiation. The PET scan is also expensive and is not typically covered by insurance as a diagnostic test. Also, few medical centers have the technology, researchers said.
Using blood samples and other data from patients with mild cognitive impairment from the Alzheimer's Disease Neuroimaging Initiative -- a large public-private partnership that began in 2004 -- the UCLA researchers found that their method could be used to predict the presence of amyloid in the brain with modest accuracy.
"Our study suggests that blood protein panels can be used to establish the presence of Alzheimer's-type pathology of the brain in a safe and minimally invasive manner,'' Apostolova said. "We need to further refine and improve on the power of this signature by introducing new disease-related metrics, but this indicates that such a test is feasible and could be on the market before long.''
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