An overactive immune system could trigger the debilitating condition chronic fatigue syndrome (CFS), a study has found.
CFS – also known as ME (myalgic encephalomyelitis) – is a long-term illness characterised by extreme tiredness, and affects approximately 250,000 people in the UK.
The underlying biology of the condition has remained a mystery, although many patients report their illness starting following an infection such as a viral illness.
Scientists at King’s College London have found that an immune system overreacting to an infection could help explain how the condition is contracted.
Lead researcher Dr Alice Russell said: “For the first time, we have shown that people who are prone to develop a CFS-like illness have an overactive immune system, both before and during a challenge to the immune system.
“Our findings suggest that people who have an exaggerated immune response to a trigger may be more at risk of developing CFS.”
Researchers from the university’s Institute of Psychiatry, Psychology and Neuroscience studied the responses of 55 patients who were given the drug interferon-alpha as a treatment for hepatitis C.
The drug activates the immune system in the same way as a powerful infection.
The 18 patients who went on to develop lasting fatigue and CFS-like symptoms had a stronger immune response to the medication.
Even before the treatment began, these patients had overactive immune systems which showed signs they may have been “primed” to over-respond, the scientists said.
Once the CFS-like illness had developed, however, there were no differences between the immune system of these patients and those who recovered as normal.
Senior researcher Professor Carmine Pariante said the results were the “first step in identifying those at risk and catching the illness in its crucial early stages”.
Dr Neha Issar-Brown, of the Medical Research Council (MRC), which funded the research, said: “CFS/ME is a serious condition and its underpinning biology is poorly understood.
“Encouragingly, this work sheds light on potential mechanisms of immune dysregulation underlying early stages of chronic fatigue syndrome.
“The MRC strongly encourages more research to better understand this condition in order to address an area of unmet clinical need.”