For decades, sufferers of chronic fatigue syndrome have battled to prove this debilitating illness is not a psychological condition, but in fact an actual biological disease. Now a team from the Stanford University School of Medicine has developed an innovative new type of blood test that could offer doctors the first diagnostic tool to identify it.

Myalgic encephalomyelitis (ME), as many sufferers prefer it called, has no known treatment or cure, is difficult to diagnose, and for much of the 20th century was not even recognized as a physical illness. Over the last few decades doctors have come to accept CFS/ME as a real and serious condition, but the problem physicians face in trying to diagnose patients suffering from it is that there are no biological markers to identify the condition. This means diagnosis tends to be one of exclusion, belatedly offered when other conditions have been ruled out.

The innovative new blood test is based on a "nanoelectronic assay" designed to measure the way tiny samples of blood affect the flow of electrical activity across thousands of electrodes. Using salt the blood samples are "stressed", which causes immune cells in the plasma to disrupt the electrical current. The larger the disruption to the electrical current, the more stressed the cells are.

An early pilot study of 40 blood samples (20 healthy and 20 with CFS/ME) revealed all from the chronic fatigue subjects created a significant disruption to the electrical current. Using these disruptions as a signpost of CFS/ME the test ultimately returned 100 percent accurate results, identifying all 20 CFS/ME patients with no false positives in the healthy cohort.

"We don't know exactly why the cells and plasma are acting this way, or even what they're doing," says Ron Davis, senior author on the new study. "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."

Not only is the new blood test a promising diagnostic tool but it also points researchers toward possible novel drug treatments. Rahim Esfandyarpour, lead author of the new study, suggests the nanoelectronic assay can be used to evaluate the efficacy of drugs that could treat CFS/ME.

"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," says Esfandyarpour.

Andrew Lloyd, from the University of New South Wales and member of the Australian National Health and Medical Research Council's CFS/ME Advisory Committee, suggests it is premature to jump to the conclusion an objective biomarker for the disease has been discovered. Lloyd, who did not work on this new research, notes the small sample size of the study, and stresses the need for broader validation in more patients.

"…the findings firstly warrant independent confirmation (i.e same findings by a different group) and then validation of the test in much larger patient numbers and a range of healthy and disease comparators (notably patients with other fatigue-associated conditions – multiple sclerosis, major depression, SLE, etc etc)," says Lloyd.

It may still be early days for the new diagnostic tool, but the researchers say they have already homed in on one drug candidate that has proven to restore blood immune cell function to normal in the assay test. The researchers claim the drug is not currently being tested on patients for chronic fatigue syndrome but will hopefully be trialed in humans soon. There is no evidence that targeting this specific biomarker will improve CFS/ME symptoms in humans, but the promising new diagnostic breakthrough offers scientists a whole host of new research pathways to work on in the battle against this crippling disease.

The new study was published in the journal PNAS.