(CNN) – According to a study, chronic fatigue syndrome, a condition that causes extreme fatigue, can be triggered by an overactive immune system.
Researchers in Britain have found that excessive immune response can trigger long-term fatigue, suggesting that this is how the condition begins, also called myalgic encephalomyelitis or MS.
The study, published on Monday, is the first to collide the role of the immune system in disease development, a multi-systemic disease not very well-known, according to leading researcher Carmine Pariante, Professor of Biological Psychiatry King's College of London.
The limited information so far has made the treatment a challenge.
Pariante explained that patients in many cases of chronic fatigue recall an infection, such as a very bad cold or other viral infection, in early stages of the disease.
"We had this information quite a while, but we did not know what was happening in the body of those patients," he said.
According to the British organization Action on ME, about 250,000 people in the United Kingdom and 17 million people around the world are affected by chronic fatigue. An estimated 836,000 to 2.5 million Americans struggle with the syndrome, according to the US Center for Disease Control and Prevention. (CDC, for its acronym in English).
To try to get more information about it, the team modeled a possible pathway to the condition based on a treatment for chronic hepatitis C infections called interferon alfa, as it is known that treatment causes sustained fatigue in some people.
The study explains that interferon alfa affects the immune system in a similar manner to a strong infection.
The researchers measured fatigue and immune activity in 55 patients receiving hepatitis C with interferon alfa.
Patients were monitored before, during and after hepatitis C treatment. Of the participants, 18 patients developed approximately one third of sustained fatigue, defined as fatigue lasting more than six months after treatment.
The long-term fatigue group also experienced a greater immune response, which is demonstrated by doubling the levels of messenger molecules in the immune system interleukin-10 and interleukin-6.
Immune markers were measured with a blood sample during the study.
The team also observed higher levels of these molecules in these patients before treatment had begun.
"What these data strongly suggest is that people who develop chronic fatigue syndrome in response to an infection do so because their immune system is ready to react in an overactive manner, Pariante explains.
It is not clear why a person's immune system may be prepared to react hyperactively, but genetics may be a possible reason, he added.