Imagine feeling horribly sick, day after day, yet doctors repeatedly tell you they can't find anything wrong. That typically happens to people with the mysterious illness commonly known as chronic fatigue syndrome. Research findings from Stanford University released Monday could point the way to a long-sought diagnostic laboratory test for the condition, and possibly a first-ever treatment.
Believed to affect at least a million people in the U.S., the condition is now increasingly termed myalgic encephalomyelitis/chronic fatigue syndrome, or ME/CFS for short.
Many patients see the name "chronic fatigue syndrome" as trivializing and misleading, giving the impression that they're simply tired or depressed. In fact, they're experiencing profound exhaustion that isn't relieved with sleep, flu-like symptoms, muscle pain, "brain fog" and various other physical symptoms, all of which characteristically worsen with even minor exertion. (A 2015 Institute of Medicine report proposed the name "systemic exertion intolerance disease," but it hasn't really stuck.)
The symptoms can range from mild to extremely severe, with about a quarter of patients so ill they're mostly or completely confined to bed. Now, the Stanford researchers have linked ME/CFS to variations in certain cytokines, immune-signaling proteins, that track with illness severity. The study results were published online Monday in the the Proceedings of the National Academy of Sciences.
The link to gradation in severity, rather than simply seeking a positive versus negative result, represents a new approach to the search for biological markers for the illness. The study involved 192 ME/CFS patients and 392 healthy controls matched for age and sex. Out of 51 cytokines investigated via sophisticated fluorescence-based testing, only two of the cytokines differed, in their total concentrations, between the ME/CFS and control groups.
But, levels of 17 of the cytokines varied dramatically between the patients with mild versus severe ME/CFS symptoms. Of those 17 cytokines, 13 were types that promote inflammation. This is significant because symptoms in these patients and findings from other studies also suggest that chronic inflammation plays a major role in the illness.