Many people, including some doctors, still believe that the illness known as “chronic fatigue syndrome” is a psychiatric or psychosomatic disorder. But scientists and health officials have increasingly recognized in recent years that the condition is a serious disease marked by significant immunological and neurological dysfunction. In many, if not most, cases it is triggered by an infectious illness, although exposure to environmental toxins, mold, or other physiologic traumas could also play a role.
In the U.S., an estimated one million people suffer from the illness, some of them largely unable to leave their homes. Most remain undiagnosed. Patients tend to dislike the term “chronic fatigue syndrome” because they believe it misrepresents and trivializes the illness. The core symptom, according to a major 2015 report from the Institute of Medicine (now the National Academy of Medicine) is not “fatigue” per se but the fact that patients experience serious relapses after even minimal exertion—a phenomenon the report called “exertion intolerance” but that is also often called “post-exertional malaise.”
Many patients therefore prefer to call the disease “myalgic encephalomyelitis,” or ME, which translates as “inflammation of the brain and central nervous system, accompanied by muscle pain.” That name was coined after an outbreak of illness at a London hospital in the mid-1950s and has been used since 1969 by the World Health Organization, which classifies it as a neurological disorder. In the U.S., government agencies now often refer to the illness as ME/CFS.
