Researchers at Stanford University have developed a potentially pathbreaking blood test that, according to preliminary studies, is able to identify patients with Alzheimer’s disease – an ailment that has been notoriously difficult to diagnose
 The test has also shown promise in predicting which patients with mild memory loss are at high risk of developing the dreaded syndrome, which kills 66,000 Americans each year and inflicts incalculable heartache on the families of its victims.
Scientists have been working for years without success to develop a simple way to diagnose Alzheimer’s disease, a degenerative brain disease that saps memory, sows confusion and will eventually kill patients who may have lost the ability to speak, walk or swallow.
In a paper published Sunday in the online edition of the British journal Nature Medicine, a team of scientists led by Stanford neurology Professor Tony Wyss-Coray describe a unique method that can spot Alzheimer’s patients by screening for a set of 18 chemical signals that consistently turn up in the blood of people suffering from the disease.
The 18 different molecules are drawn from a phrase book of chemical chatter that occurs among cells in the body. Together, they present a pattern that with surprising consistency appears in the blood of Alzheimer’s patients.
“These are signaling proteins that cells use to communicate with each other,” Wyss-Coray explained. “Our idea was to ask, ‘What are the most important proteins we could find in Alzheimer’s patients?’ ”
The Stanford professor and his team screened 120 such proteins that commonly circulate in the blood and settled on 18 that showed the signature of Alzheimer’s. Using existing laboratory technology, they developed a test that will light up when the 18 molecules are present in a blood sample.
In one experiment using stored blood samples, the test was positive for Alzheimer’s disease in 38 out of 42 patients who had been independently diagnosed by clinicians as having the disease – a 90 percent accuracy rate. It also classified as non-Alzheimer’s disease 34 out of 39 who did not have the illness, but nevertheless suffered from other dementias or mild cognitive impairments – 87 percent accuracy.
More intriguing is a test that examined stored blood samples and predicted Alzheimer’s disease in 20 of 22 patients who developed the disease two to five years later. Eight patients who subsequently developed other forms of dementia were correctly diagnosed as non-Alzheimer’s.
Although the studies were small in scale, researchers said the experiment proves that the concept of screening for chemical signals is promising and that the first Alzheimer’s blood test might be within reach after further large-scale studies.
“I do see great potential in this technology,” said UCSF professor Dr. Lennart Mucke, director of the Gladstone Institute of Neurological Disease. “This study shows that the chemical fingerprint found in the blood of these patients was pretty reliable. It could be a terrific addition to our diagnostic toolbox.”
Mucke acknowledged that there are very few medical treatments for patients once they are diagnosed with Alzheimer’s. But he said a test showing the likelihood that the disease will develop would help patients and family members prepare for what lies ahead.
“I’m personally a proponent of knowing what is ahead. It is important for us to increase the number of people who realize they are at risk and can still speak out for themselves,” he said.
Mucke has no financial interest in the technology, although Wyss-Coray trained in his laboratory.
The test initially will be used in research labs, where scientists are trying to learn more about the memory-wasting disease that is one of the most feared consequences of aging. An estimated 4.5 million people in the United States are living with the disease.
Wyss-Coray has founded Satoris Inc., a small company headquartered at the UCSF campus in Mission Bay, to commercialize the technology. He said it will take at least two years and additional studies before such a test might reach clinics around the country.
Dr. Jerome Goldstein, director of the San Francisco Alzheimer’s and Dementia Clinic, said there are very few objective tests to diagnose Alzheimer’s disease, and most of them are complex and expensive. MRI scans, for example, can detect shrinkages in parts of the brain targeted by the disease.
Goldstein’s clinic is involved in other experimental tests, such as one to detect ApoE, a protein implicated in Alzheimer’s disease, as well as other uses of MRI and PET scans. While much of the scientific work, including that at Stanford, is promising, Goldstein said all the technologies are a long way from being available in clinics.
Source: San Francisco Chronicle, Sabin Russell, Chronicle Medical Writer
