A glimmer of hope for people living with chronic fatigue syndrome
Myalgic encephalomyelitis (ME), long known as chronic fatigue syndrome, is now recognized as a complex, multi-system disease. However, it remains a medical enigma whose underlying causes are poorly understood, leaving those affected with few effective treatment options.
Alain Moreau, a professor in the Department of Biochemistry and Molecular Medicine and the Department of Stomatology at Université de Montréal and a researcher at the CHU Sainte-Justine Research Center, has been working to solve this puzzle.
Moreau now devotes much of his research to shedding light on the many unresolved issues surrounding ME, such as the role of genetic predisposition and the underlying biological mechanisms of the disease.
Cluster of interconnected symptoms
ME affects many body systems and produces a wide range of symptoms, including muscle pain and weakness, cognitive difficulties (often described as brain fog), autonomic disorders such as digestive problems, postural hypotension and sleep disturbances.
But the defining symptom of ME is post-exertional malaise, a state in which minor exertion—physical, mental or emotional—precipitates a significant worsening of symptoms that can last for hours, days or even weeks.
One of the greatest challenges in studying ME is the heterogeneity of triggers, symptom clusters and disease progression.
“ME is not a single disease but rather a spectrum comprising several subgroups,” said Moreau. “Accurate diagnosis is difficult because ME and fibromyalgia present with very similar symptoms that can fluctuate over time. Our molecular analyses have shown that up to 40% of individuals diagnosed with ME are in fact suffering from fibromyalgia—and it’s possible to have both conditions at the same time.”
Long COVID and epigenetics
In about 75% of cases, ME develops after a viral infection. Common triggers include the Epstein-Barr virus (mononucleosis), the influenza virus (the flu), West Nile virus, chikungunya, Zika and, more recently, SARS-CoV-2 (COVID-19).
“Long COVID is a good example,” said Moreau. “It isn’t an entirely new disease but more an intersection of various post-infectious pathways. Among those with the most persistent and severe symptoms, a significant proportion eventually meet the criteria for ME.
“In other words, with COVID-19, medicine is rediscovering a condition already known to follow other infections, such as mononucleosis or the flu. It’s surprising that so many people think long COVID is a new disease. Actually, it’s just another post-infectious syndrome similar to conditions such as Lyme disease.”
Despite considerable effort, genetic research has yet to identify a clear cause of ME. Genetic variations explain only a small fraction of sporadic cases, although some families are clearly more genetically predisposed than others.
In a recent study published in DNA, Moreau and his team demonstrated that epigenetics, which examines how environmental factors change gene expression without altering the DNA sequence itself, is a more promising avenue for understanding the cause of ME. Factors such as infections and toxins, including heavy metals and molds, can effectively reprogram specific biological mechanisms
