Chronic fatigue syndrome, a condition where normal exertion leads to debilitating fatigue that isn’t alleviated by rest, has long mystified scientists. There are no known triggers, and diagnosis requires lengthy tests.
Some have suggested the disease may be psychosomatic.
Now, for the first time, researchers report they have identified biological markers of the disease in gut bacteria and inflammatory microbial agents in the blood.
In a new study published in the journal Microbiome, scientists describe how they correctly diagnosed myalgic encephalomyeletis/chronic fatigue syndrome (ME/CFS) in 83 percent of patients through stool samples and blood work, offering a noninvasive diagnosis and taking a step toward understanding the cause of the disease.
“Our work demonstrates that the gut bacterial microbiome in ME/CFS patients isn’t normal, perhaps leading to gastrointestinal and inflammatory symptoms in victims of the disease,” says lead author Maureen Hanson, professor of molecular biology and genetics. “Furthermore, our detection of a biological abnormality provides further evidence against the ridiculous concept that the disease is psychological in origin.”
“In the future, we could see this technique as a complement to other noninvasive diagnoses, but if we have a better idea of what is going on with these gut microbes and patients, maybe clinicians could consider changing diets, using prebiotics such as dietary fibers or probiotics to help treat the disease,” says postdoctoral researcher Ludovic Giloteaux, first author of the study.
Researchers have evidence that an overactive immune system plays a role in chronic fatigue. Symptoms include fatigue even after sleep, muscle and joint pain, migraines, and gastrointestinal distress. One hallmark of the condition is post-exertional malaise, meaning patients may take weeks to recover from minor exertion. To test for ME/CFS, clinicians may give patients a cardio-pulmonary exercise test where they ride a bike until they become fatigued. If the test is repeated the following day, ME/CFS patients usually cannot reproduce their performance from the first day.
“That’s very typical and specific of people with ME/CFS, because healthy people, or even people who have heart disease, can reproduce the exercise on the second day, but these people cannot,” Giloteaux says.
The study included 48 people diagnosed with ME/CFS and 39 healthy controls to provide stool and blood samples. Researchers sequenced regions of microbial DNA from the stool samples to identify different types of bacteria. Overall, the diversity of types of bacteria was greatly reduced and there were fewer bacterial species known to be anti-inflammatory in ME/CFS patients compared with healthy people, an observation also seen in people with Crohn’s disease and ulcerative colitis.
At the same time researchers discovered specific markers of inflammation in the blood, likely due to a leaky gut from intestinal problems that allow bacteria to enter the blood. Bacteria in the blood will trigger an immune response, which could worsen symptoms.
The researchers have no evidence to distinguish whether the altered gut microbiome is a cause or a whether it is a consequence of disease, Giloteaux says.
In the future, the team will look for evidence of viruses and fungi in the gut, to see whether one of these or an association of these along with bacteria may be causing or contributing to the illness.
The National Institutes of Health funded the work.
Source: Cornell University