Scientists have developed a test for chronic fatigue syndrome that detects the reaction of the immune cells and blood plasma to stress. The findings may also help screen effective drugs for the condition.

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Scientists have developed and tested a new diagnostic tool for ME/CFS.

Myalgic encephalomyelitis, or chronic fatigue syndrome (ME/CFS), is a serious condition that may affect up to 2.5 million people in the United States.

Symptoms include extreme tiredness, difficulty sleeping, trouble with thinking and remembering things, muscle pain and aches, a recurring sore throat, and tender lymph nodes.

Currently, physicians can only diagnose ME/CFS by examining a person's symptoms and medical history, and by excluding other possible illnesses.

This can make the diagnosis process difficult, lengthy, and inaccurate.

However, the results of a new study may soon change this. Scientists at Stanford University School of Medicine in California have discovered a biomarker for ME/CFS and developed a test that could soon diagnose the condition accurately.

Ron Davis, Ph.D. — a professor of biochemistry and of genetics at Stanford University School of Medicine — devised the test together with his team, which includes first study author Rahim Esfandyarpour.

Prof. Davis and colleagues published their findings in the journal Proceedings of the National Academy of Sciences.

How does the test work?

Prof. Davis shares the motivation for his research, saying, "Too often, [ME/CFS] is categorized as imaginary." He goes on to explain that physicians often misguidedly test liver, kidney, and heart function, as well as take blood samples and immune cell counts from people who seek help for ME/CFS.

"All these different tests would normally guide the doctor toward one illness or another," says Prof. Davis, "but for [people with ME/CFS], the results all come back normal." The issue, he adds, is that none of these tests look deep enough.

Instead, their new diagnostic test looks at how a person's immune cells react to stress. Specifically, the scientists used a nanoelectronic assay, which measures small changes in energy to assess the health of immune cells and blood plasma, to see how the immune cells and blood plasma process stress.

To develop the test, the team took advantage of "advancements in micro/nanofabrication, direct electrical detection of cellular and molecular properties, microfluidics, and artificial intelligence techniques."

The test detects "biomolecular interactions in real time" by using thousands of electrodes to create an electrical current, and by using small chambers that contain blood samples with only immune cells and blood plasma.

Inside the small chambers, the immune cells and plasma interact with the electrical current, altering its flow.

The scientists used salt to stress the blood samples of some people with ME/CFS and some people without the condition. They then assessed the changes in electrical current.

The bigger the changes, the less healthy the blood sample, explain the scientists; the changes in electrical current reflect the changes on a cellular level. A significant change indicates that the immune cells and blood plasma do not react well to stress and cannot process it effectively.

In the experiments that Prof. Davis and team carried out, all of the blood samples that came from people with ME/CFS showed a clear spike indicating large changes in electrical current, whereas blood samples from people who did not have the condition showed an even course.

"We don't know exactly why the cells and plasma are acting this way, or even what they're doing," says Prof. Davis. However, the findings offer "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."

Prof. Ron Davis

The researchers applied the test to the blood samples of 40 people, 20 of whom had ME/CFS and 20 whom did not.

Their test accurately identified all of the people with ME/CFS without misidentifying any of the people who did not have the condition.

Also, they wish to apply the test to identify effective drugs for ME/CFS. "Using the nanoelectronics assay," explains Esfandyarpour, "we can add controlled doses of many different potentially therapeutic drugs to the patient's blood samples and run the diagnostic test again."

This way, if the test still finds spikes in electrical current after the treatment, it means that the drug didn't work and the immune cells still respond poorly to stress. However, if the drug smoothes out the spikes, it could mean that they are helping the immune cells and blood plasma process stress more effectively.