Blood test to help detect Alzheimer’s disease developed

18 October, 2007

A revolutionary blood test that is able to identify patients with Alzheimer’s disease has been developed.

Alzheimer’s disease, which is difficult to diagnose, takes about 66,000 lives in the United States each year and inflicts immense agony on the families of its victims. The degenerative brain disease takes away memory, sows confusion and eventually kills the patient who may have lost the ability to speak, walk or swallow.

The new test, developed by researchers at Stanford University, located in Palo Alto, California, the United States, has also shown the potential in predicting which patients with mild memory loss are at high risk of developing the dreaded syndrome.

Scientists have been working for years without success to develop a simple way to diagnose Alzheimer’s disease.
In a paper published on October 15, 2007, in the online edition of the British journal Nature Medicine, a team of scientists led by Tony Wyss-Coray, professor of neurology at Stanford University, 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 which, with surprising consistency, appears in the blood of Alzheimer’s patients.

Prof Wyss-Coray explained: “These are signaling proteins that cells use to communicate with each other. Our idea was to ask, ‘what are the most important proteins we could find in Alzheimer’s patients?”


Prof Wyss-Coray and his team screened 120 such proteins that commonly circulate in the blood and settled on 18 that showed the signature of Alzheimer's disease. 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 – which is a 90% 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 – with 87% accuracy.

According to the researchers, more intriguing was a test that examined stored blood samples and predicted Alzheimer’s disease in 20 out of 22 patients who developed the disease 2 to 5 years later. Eight patients who subsequently developed other forms of dementia were correctly diagnosed as non-Alzheimer’s.

Admitting that the studies they conducted were small in scale, the researchers said the experiment proves that the concept of screening for chemical signals is promising and that the first blood test for Alzheimer’s disease might be within reach after further large-scale studies.