Scientists in New Jersey now say they have developed a new, simple blood test that can identify the presence of Alzheimer’s with 96% accuracy, and rule out the presence of Alzheimer’s with 92.5% accuracy, in a sample of persons already diagnosed by other means to have or not to have the disease.
”This is a simple test that has high accuracy and can be run from a single drop of blood,” said the test’s developer, Robert Nagele, PhD, who is a professor of medicine at the University of Medicine and Dentistry of New Jersey School of Osteopathic Medicine, and is also the founder of Durin Technologies, Inc., a New Jersey company that is working to develop and make the blood test commercially available.
The findings are reported in a scientific study published in the August, 2011 issue of PLoS ONE, an open access online publisher of peer-reviewed scientific research. The authors of the study include Dr. Nagele and his colleagues at the University of Medicine and Dentistry of New Jersey.
Dr. Nagele and colleagues analyzed blood samples from 50 people already diagnosed to have Alzheimer’s disease and 40 who did not have the disease. They also analyzed blood samples from 30 breast cancer patients and 29 patients with Parkinson’s disease, in order to ascertain that their blood test could specifically identify those with Alzheimer’s and differentiate them from patients with these other conditions.
“Parkinson’s and Alzheimer’s are very close in terms of their pathology,” Dr. Nagele explained. “Neurons are dying in both cases,” he said. He wanted to be sure that his blood test could correctly differentiate between the two.
Based on this analysis, Dr. Nagele and his colleagues identified certain antibodies in the blood specific to Alzheimer’s disease. In the process, they discovered thousands of antibodies in the blood, many of which they believe may relate to Alzheimer’s, and from these, they isolated 10 antibody biomarkers which together, they found capable of detecting the presence of Alzheimer’s disease.
Within the study sample, the researchers found that the presence of these 10 antibodies in the blood successfully identified 96% of those who had Alzheimer’s disease. The absence of these 10 antibodies also successfully identified 92.5% of those in the study who did not have Alzheimer’s. And, the researchers reported that the blood test was able correctly to differentiate between those who had Alzheimer’s and those who had the similar Parkinson’s or the other conditions measured.
Alzheimer’s is widely believed to begin up to 10 or more years before symptoms actually appear and are noticeable.
However, before symptoms occur, brain changes are under way, Dr. Nagele explained. “Brain cells die and when they die, they pop, they explode, like a water balloon breaking,” he told WebMD.
The contents of those dying cells are released partially back into the blood. “Your body makes antibodies against the cell debris,” Dr. Nagele explained. “We believe that happens so it can facilitate the cleanup of the cell debris,” he said.
This may explain why certain antibodies found in the blood were able to predict the presence of Alzheimer’s, according to the researchers.
The researchers caution, however, that their study so far has only shown an ability of their blood test to identify those who already have been diagnosed as having Alzheimer’s (based on their apparent symptoms and other existing means) out of a small sample of persons. The test has not yet been proved able to detect the disease in advance, before symptoms appear.
Dr. Nagele expresses hope that his test may eventually be shown able to detect the disease before symptoms appear. His company hopes to make the test commercially available within a year, at a cost roughly projected to be about $200, he told WebMD.
As reported by the Alzheimer’s Association, an estimated 5.4 million Americans have Alzheimer’s disease, the most common form of dementia, and that number is rapidly growing in epidemic proportions, as our population ages.
Currently, there is no definitive way to diagnose the disease, other than by an autopsy examination of brain tissue after the patient dies. Doctors now use observation of apparent symptoms of the disease, brain imaging, psychiatric tests, behavior evaluation, and other means to diagnose the disease indirectly. “None of these methods by themselves or in combination provide for early detection or yield high accuracy,” Dr. Nagele and his colleagues wrote in an introduction to their study.
There has been an increasing push to develop more accurate and less invasive means of reaching an early diagnosis of Alzheimer’s.
According to Heather Snyder, PhD, a spokesperson for the Alzheimer’s Association, while some people may not want to know if they are in the early stages of this dreaded disease, nevertheless knowing in advance has many advantages. With an early diagnosis, “[patients] can plan for their financial future, as well as their care,” she explained to WebMD. “They can participate in clinical trials. When we do have therapeutic options available, the ultimate goal would be intervention,” she said.
Dr. Snyder, who reviewed the test results for the new blood test, termed Dr. Nagele and his colleagues’ research “preliminary.” “It’s a small study and a small sample,” she said.
Dr. Snyder indicated that many other scientists are also working on developing blood tests and other methods, such as cerebral spinal fluid tests, to diagnose Alzheimer’s. For example, at the July 2011 Alzheimer’s Association International Conference, Australian researchers reported positive results for another blood test they are developing. Their test detects Alzheimer’s by determining the amount of amyloid plaque, a substance associated with the disease, found in the patient’s brain.
“Many labs are looking at this,” Dr. Snyder said. “They are all in the very preliminary, very early stages. We all know we need an accurate, relatively noninvasive way to diagnose Alzheimer’s.”
For early diagnosis, however, one may question whether 99.9% to 100% accuracy isn’t crucial in order to avoid potential risks of doing psychological harm to patients by delivering a wrong diagnosis.
The full study report on the new blood test, Diagnosis of Alzheimer’s Disease Based on Disease-Specific Autoantibody Profiles in Human Sera, is available in the August, 2011 issue of PLoS ONE.
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