Researchers at the Stanford University School of Medicine have linked chronic fatigue syndrome (also known as CFS or ME) to variations in 17 immune-system proteins, whose concentrations in the blood correlate with the disease’s severity.
The findings, which have been published in the Proceedings of the National Academy of Sciences, provide evidence that inflammation drives the condition, and could lead to improved diagnosis and treatment of the little-understood disorder.
Chronic fatigue syndrome is estimated to affect around 200,000 people in the UK, and typically persists for decades. There is no known cure or reliably effective treatment. Three of every four patients are women, and it usually arises in two major waves; among adolescents between the ages of 15 and 20, and in adults between 30 and 35.
Many, but not all, patients with the condition experience flulike symptoms common in inflammation-driven diseases. But because its symptoms are so diverse – manifesting as anything from heart problems to muscle pain – it often goes undiagnosed.
The researchers analysed blood samples from 192 patients with the condition, as well as from 392 healthy control subjects. They found that some cytokine levels were lower in patients with mild forms of ME/CFS than in the control subjects, but elevated in patients with relatively severe manifestations, particularly those that are pro-inflammatory.
One of the cytokines whose levels corresponded to disease severity, leptin, is secreted by fat tissue. Generally it is more abundant in women’s blood than in men’s, which could help to explain why the condition is so much more common in women.
The researchers say the study results could lead to clinical trials testing immunomodulatory drugs’ potential as therapies for chronic fatigue syndrome.
The study’s senior author, Mark Davis, said: ‘There’s been a great deal of controversy and confusion surrounding ME – even whether it is an actual disease. Our findings show clearly that it’s an inflammatory disease and provide a solid basis for a diagnostic blood test.’