New York, Feb 28 (IANS): Researchers have found evidence that chronic fatigue syndrome (CFS) is a result of immunological dysfunction, meaning it is a biological illness and not a psychological disorder as commonly thought.

People with CFS or systemic exertion intolerance disease experience extreme fatigue and difficulty concentrating due to headaches and muscle pain.

"We now have evidence confirming what millions of people with this disease already know, that CFS is not psychological," stated lead author Mady Hornig, director of translational research at the Center for Infection and Immunity, Columbia University.

"Our results should accelerate the process of establishing the diagnosis after individuals first fall ill as well as discovery of new treatment strategies focusing on these early blood markers," Hornig added.

The researchers identified distinct immune changes in patients diagnosed with chronic fatigue syndrome, known medically as myalgic encephalomyelitis (ME/CFS).

They used immunoassay testing methods to determine the levels of 51 immune biomarkers in blood plasma samples collected through two multicenter studies that represented a total of 298 ME/CFS patients and 348 healthy controls.

They found specific patterns in patients who had the disease for three years or less that were not present in controls or in patients who had the disease for more than three years.

Short duration patients had increased amounts of many different types of immune molecules called cytokines.

The association was unusually strong with a cytokine called interferon gamma that has been linked to the fatigue that follows many viral infections, including Epstein-Barr virus (the cause of infectious mononucleosis).

"This study delivers what has eluded us for so long: unequivocal evidence of immunological dysfunction in ME/CFS and diagnostic biomarkers for disease," senior author W. Ian Lipkin from Columbia University's Mailman School of Public Health noted.

The study appeared in the journal Science Advances.