A blood test that can diagnose chronic fatigue syndrome and that could potentially help identify treatments for the baffling illness has been discovered by Stanford University School of Medicine and U.C. Irvine researchers.
Using a "nanoelectronics assay" they developed, the researchers were able to test how a person's immune cells respond to a particular stressor and successfully identified 100% of the patients who had chronic fatigue syndrome during a pilot study. Using blood samples from 40 people, the test accurately flagged all 20 chronic fatigue syndrome patients and none of the 20 healthy individuals in the control group.
The researchers -- senior author Ronald W. Davis, a professor of biochemistry and of genetics at Stanford School of Medicine; lead author Rahim Esfandyarpour, a University of California-Irvine assistant professor of electrical engineering and computer science, and their colleagues -- published their breakthrough in a paper online in the "Proceedings of the National Academy of Sciences" in late April.
Prior to their assay, no standard test had been devised to diagnose myalgic encephalomyelitis/chronic fatigue syndrome. The disease, which is little understood and often discounted as a psychological condition, causes a constellation of symptoms. The most pronounced aspect is extreme exhaustion exacerbated by stimuli and mental and physical activity. The sufferer cannot recover through normal rest or sleep. The disease appears to affect multiple organ systems in the body.
An estimated 836,000 to 2.5 million Americans have chronic fatigue syndrome, according to the U.S. Centers for Disease Control, but some researchers estimate that more than 91 percent of patients with the illness have not yet been diagnosed.
Several studies have found the disease might be triggered by a combination of factors such as major life stressors, viral infection, stomach viruses, bacterial infections, toxin exposure, immunodeficiency, nutritional deficiencies, genetic susceptibility, and several other contributors, the researchers noted.
Davis, of Palo Alto, has been searching for identification markers for the disease since his son, Whitney Dafoe, came down with the disease a decade ago.
The test could also help others from experiencing what his family has encountered over the years.
"This test clearly distinguishes ME/CFS patients from healthy people, so it should put a stop to doctors telling patients that there is nothing wrong with them or that it's only in their heads or a 'false illness belief'. I believe this will a big step for millions of patients. We are working hard to make it usable easily and cheaply for doctors," Davis said in a email.
Tests that would normally guide a doctor's diagnosis -- of a patient's liver, kidneys, heart function, blood and immune cell counts -- "for chronic fatigue syndrome patients, the results all come back normal," Davis, a genetics researcher who was instrumental in the Human Genome Project, said.
In their study, the researchers chose patients with moderate-to-severe chronic fatigue syndrome. They focused on peripheral blood mononuclear cells, which are blood cells that are critical for the immune system to fight infection and adapt to invasive pathogens.
The assay measured changes in amounts of energy flowing from thousands of sensors in the assay through the plasma and immune cells they extracted from the chronic fatigue and the healthy participants' blood. The scientists stressed the samples using salt, a commonly used stressor in studies on plant, yeast, bacteria, mice, and human cells. They compared how the blood components from the healthy and chronic fatigue patients affected the flow of the electrical current. The blood samples from all of the chronic fatigue syndrome patients showed a clear spike in the electric current, a sign the cells and plasma are incapable of effectively processing the salt stressor. Samples from the healthy patients were relatively even.
"We don't know exactly why the cells and plasma are acting this way, or even what they're doing. But there is scientific evidence that this disease is not a fabrication of a patient's mind. We clearly see a difference in the way healthy and chronic-fatigue-syndrome immune cells process stress," Davis said.
Th researchers are now expanding their testing with more participants to confirm their findings.
Using supervised machine learning algorithms, they also developed a classifier for chronic-fatigue patients that is capable of identifying new patients when their blood is assayed.
The assay is also being used to test FDA-approved drugs or those that will soon be available to the public to find potential treatments.
"Using the nanoelectronics assay, we can add controlled doses of many different potentially therapeutic drugs to the patient's blood samples and run the diagnostic test again," Esfandyarpour said in the statement.
If the blood samples still respond poorly to stress in electrical-current tests, then the drug likely didn't work. A drug that seems to reduce the spike in the electrical current could indicate it is facilitating the immune cells and plasma to process stress, they said.
The researchers have already found a drug that seems to restore healthy function to immune cells and plasma, they said. But the drug is not currently being used in people with chronic fatigue syndrome. The researchers are hopeful they can test the medication in a future clinical trial.
The scientists plan to test the performance of the assay on other diseases manifesting similar conditions. They are also working on adapting the technology to develop a portable, handheld and easy-to-use device that can be operated by researchers and clinicians at any skill level.
The study was funded by the Open Medicine Foundation. Davis is the director of the foundation's scientific advisory board.
• Unraveling the mystery of chronic fatigue syndrome, July 2015