A blood test for chronic fatigue syndrome (CFS) could be on the cards after scientists identified the first known biomarker for the condition.
The test, still under development, measures the way immune cells respond to stress.
According to researchers, it offers definitive proof that the illness is real and not imaginary.
CFS, also known as myalgic encephalomyelitis (ME), causes feelings of extreme tiredness often combined with flu-like symptoms and joint pains.
An estimated 250,000 people in the UK suffer from the condition, some affected so badly they cannot work or carry out everyday tasks without help.
Yet because the causes of CFS are largely unknown, it is often perceived as being “in the mind”.
Professor Ron Davis, from Stanford University School of Medicine in the US – who led the new research, said: “Too often, this disease is categorised as imaginary.
“When individuals with chronic fatigue syndrome seek help from a doctor, they may undergo a series of tests that check liver, kidney and heart function, as well as blood and immune cell counts.
“All these different tests would normally guide the doctor toward one illness or another, but for chronic fatigue syndrome patients, the results all come back normal.”
The unusual test, described in the journal Proceedings of the National Academy of Sciences, allows immune cells in a blood sample to interfere with an electric current.
The change in electrical flow reflects the health of the cells.
When blood samples from healthy and ill individuals were stressed using salt, the test produced a clear spike from CFS patients showing that their immune cells were failing.
Prof Davis said: “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.”
The test is also being used to screen candidate drug treatments.
The team claims to have already found one drug, not currently being used to treat CFS, that appears to restore healthy function to immune cells.
