Could modern medicine be nearing a diagnosis for Alzheimer’s disease (AD)?

A team of international researchers has reported the identification of a group of cell-signaling proteins found in blood that serve as a unique “voiceprint” that can be used not only to diagnose Alzheimer’s disease, but also classify and predict presymptomatic individuals who will eventually develop the memory-robbing disorder.

If the finding is proven effective and accurate in studies across broad populations, it offers a major breakthrough not only in diagnosing but, it is hoped, in finding effective therapeutics for AD.

Thus far, the only sure diagnosis of AD is autopsy, anything earlier than that being subjective guesswork.

The study describing the new test appears in the online version of the journal, Nature Medicine.

The study concludes a year-long effort led by researchers at Satoris (San Francisco), in collaboration with leading dementia centers in the U.S. and Europe. The researchers collected a total of 259 blood samples from individuals with presymptomatic to late-stage AD, and from those without the disease.

Using a so-called “signal profiling,” they were able to simultaneously measure the relative abundance of 120 known proteins found in plasma that function as chemical messengers between blood cells, brain cells, and cells of the immune system.

“We looked at 120 proteins in these blood samples,” Patrick Lynn, CEO of Satoris, told Diagnostics & Imaging Week. “We found that some of these are important in distinguishing AD from non-AD subjects. Most of these proteins are involved in cellular communication from one organ to another.

“These proteins released from one organ can interact with and affect others — they are signals sent out by the body, and are involved in many functional areas, such as neuroprotection and inflammation,” Lynn said.

“Our technology enables us to ‘listen’ to the chatter of cells communicating with each other and determine if there’s anything abnormal,” said Tony Wyss-Coray, PhD, a lead scientist in the study, and a co-founder of Satoris. “Our data indicate blood contains a highly specific, biological signature that can characterize Alzheimer’s disease years before a clinical diagnosis can be made,” he told D&IW.

Wyss-Coray is also associate professor of neurology at Stanford University School of Medicine (Stanford, California).

Statistical analyses of the two groups of blood samples showed there were 18 proteins in the AD samples that expressed distinctly different concentrations from those in normal individuals. The different protein expression pattern found in the AD samples was statistically significant, with nearly 90% accuracy in diagnosing and characterizing the disease.

Lynn said the new blood test will need further testing and corroboration before it is ready for commercialization.

He told D&IW: “Initially, Satoris plans to launch a research use only [RUO] test using a validated clinical platform for the detection of AD. As the name suggests, this first test will be primarily for researchers in academic centers and in pharmaceutical companies. Later, we hope to make an AD test available for use by physicians for their patients ...Our business strategy is two-fold, and centers on a service-based business model.

“First, we hope that the RUO test will be of benefit immediately to researchers of AD, and to pharmaceutical companies developing medicines to treat AD. Second, we hope to make a test available to physicians to aid in the diagnosis of patients who may have AD.

“In the future, we are planning to commercialize a test that will distinguish AD from other dementias, and may put out a test for specific types of dementia, such as Frontotemporal Dementia.”

There is no cure for AD, a degenerative brain disease that affects 4.5 million Americans. Experts predict the toll may more than triple by 2050 as the population gets progressively older. Since its destructive effects may exist years before symptoms are apparent, much damage can occur prior to diagnosis.

Currently, even making the most probable diagnosis of AD is costly, and largely dependent on the subjective judgment of the physician. As a result, it is estimated that only 60% of cases are judged as actual AD, leaving 1.8 million undiagnosed patients. And, as noted, autopsy is the only final determinant of the disease.

“The early diagnosis of Alzheimer’s disease would be greatly improved by the discovery of biological markers that correlate strongly with pathological and clinical signs of the disease, and precede the appearance of clinical symptoms,” said Todd Golde, MD, PhD, professor, chair of the department of neuroscience at the Mayo Clinic (Jacksonville, Florida).

“This blood test, if replicated in larger studies, is a major discovery that may lead to more effective therapies to slow the disease’s progression or improve existing symptoms, reducing overall healthcare costs.”

As to its role in the ultimate goal of finding a cure for AD, Lynn told D&IW that Satoris is focused “on the diagnostic side of the business, although we hope to help pharma develop better medicines. The long-term goal here would be to develop surrogate markers of efficacy related to drugs — that’s a big deal and would require a lot of data from clinical trials.”