I first learned about Chronic Fatigue Syndrome (CFS) from a popular magazine that called it "Yuppie flu." I should have looked for better sources of medical information, because that term clouded my view of the condition for years. And I wasn't the only one.
A number of misconceptions and much speculation surround this mysterious disorder. Here are a few of the most common. Each is currently either unproven or untrue. But that could change over time. So, rather than calling them "myths," let's call them "claims."
Claim #1: There is no set definition of CFS.
This used to be true. But in 1994 the U.S. Centers for Disease Control and Prevention (CDC) and other international experts developed criteria to help define the condition partly to be reasonably confident that different researchers were studying the same disease. Practicing physicians may not routinely use these criteria in diagnosing an individual patient, but they are still the best definition of the condition we have.
Besides persistent unexplained fatigue that is severe enough to impair activity, the diagnosis requires at least four of the following symptoms:
- Poor memory or reduced concentration
- Sore throat
- Sore lymph nodes in the neck or under the arms
- Pain in the muscles
- Joint pain, without evidence of swelling or warmth
- Headaches (either increasing in severity or of recent onset)
- Need for more sleep despite getting plenty of sleep
- Feeling unwell for a day or more after physical activity
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Claim #2: CFS is a new disease.
Actually, conditions with symptoms strikingly similar to CFS go back at least several hundred years, although they went by different names. For example, it the mid-1700s, a condition called "Febricula" (little fever) was popular, while in the 1870s, a similar disorder was called "DaCosta's syndrome" (named for the American internist who described "utter fatigue with effort"). At the turn of the last century, "neurasthenia" was the accepted name, while "myalgic encephalitis," "Iceland disease," and "Royal Free disease" were used in different parts of the 1900s in different parts of the world. Names based on presumed causes were also common, including:
- Chronic brucellosis — Brucella is a bacteria that can be transmitted to humans from cattle, most commonly through unpasteurized milk; symptoms include fever and fatigue; the connection between brucella infection and CFS was popular in the 1930s to 1950s but has since been discounted.
- Hypoglycemia — Low blood sugar was thought to be a common cause of fatigue, including CFS during the 1950s to 1970s.
- Chronic Epstein-Barr Virus (EBV) — The virus that causes mononucleosis was thought to persist in the body.
- Multiple Chemical Sensitivity Syndrome — Many people (and some physicians) believe that extensive allergies or reactions to minute amounts of chemicals in the air or by contact may cause a CFS-like illness.
- Chronic candidiasis (or chronic yeast infection)
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Claim #3: CFS is due to an infection.
As the names above suggest, infection has long been considered a possible cause of CFS. This hasn't been proven, but it’s understandable that an infection — one that the immune system cannot completely eliminate — would be the prime suspect. Part of the appeal of this theory is that CFS can begin suddenly in a previously healthy person, much the way that the flu or other severe, acute infections begin.
There are many infectious diseases that cause prominent fatigue for prolonged periods: mononucleosis, hepatitis B and C are good examples. However, despite extensive research to identify an infectious cause, there is no conclusive evidence that CFS is an infectious illness.
Even so, that does not rule out the possibility that a chronic infection (or the “fallout” from an infection) is to blame. In fact, recent research has focused on a herpes virus (called HHV-6), a common viral cause of rash and fever in infants and young children. Because most adults (95%) have been infected with this virus during childhood and because it can persist in the body for many years, it should not be surprising that this virus would be a focus of study for CFS researchers. Perhaps the virus is contained enough by the body to prevent damage to vital organs. But its persistence in the body might cause symptoms of low grade fever, fatigue and the other symptoms of CFS.
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Claim #4: CFS only affects women.
It's true that there's a higher incidence of CFS among women than among men, but the ratio is only 2 to 1. And while those most affected are between the ages of 25 and 45, it can affect people of all ages, ethnic groups and economic backgrounds in addition to either gender. So, the idea that it only affects women or "yuppies" (young urban professionals) is not true.
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Claim #5: All test results are normal.
Many routine tests for causes of fatigue are normal in CFS. In fact, that's part of the definition of the disease: to make the diagnosis of CFS, a doctor must rule out other causes of fatigue. So, blood counts, kidney function, liver tests, and thyroid tests are routinely checked to rule out anemia, kidney failure, hepatitis or thyroid disease as the cause of symptoms. These normal findings have led some physicians and patients to question whether CFS is "real."
However, normal test results for common causes of fatigue doesn't mean all tests are normal. Actually, tests of brain function are often abnormal. For example, the hypothalamus and pituitary gland, key parts of the brain that control a number of hormones and many of the body's vital functions, frequently demonstrate abnormal activity in people with CFS. In addition, many people with CFS have abnormal blood pressure responses to changes in position, suggesting that brain signals to the nerves controlling blood pressure are not functioning properly. Some researchers have found abnormal numbers or types of white blood cells, antibodies, or tests of immune function.
Despite these findings, abnormal test results are not consistent or unique enough to suggest a cause or a treatment for CFS; and many people without CFS have similarly abnormal test results. So far, it’s still uncertain if the abnormalities found in some people with CFS are related to the cause or an effect of the disease. In other words, we don't know if abnormal hypothalamus function triggers some cases of CFS or if CFS sometimes leads to abnormal hypothalamus function.
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Claim #6: CFS is due to an undiagnosed medical illness.
This one is tricky. It's true that no specific medical illness has yet been identified as a cause of CFS. So at the present time, most physicians will consider this claim as false. In fact, researchers have noted more persistent and debilitating symptoms among people who believe an overlooked medical disease caused their CFS. But maybe these people are right! Just because no cause has been found yet doesn't mean one won't be found in the future. For a condition that can create such debilitating symptoms, physicians and researchers should acknowledge the lack of proof or disproof and at least consider the possibility that an underlying medical illness is to blame for CFS.
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Claim #7: People with CFS can't exercise.
While exercise often makes symptoms worse in the short run, exercise is a mainstay of treatment for CFS. It's important that a person with CFS starts working out slowly and very gradually increases the amount of exercise over time. Some people suffering with CFS can't even tolerate minimal amounts of activity. But for most, it's beneficial. While a number of medications have been studied in the treatment of CFS, the best documented treatments for CFS don't involve medication: exercise and cognitive behavior therapy (a form of counseling).
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The Bottom Line
While fatigue is a particularly common complaint, not all fatigue is CFS. There is much we do not understand about this condition. Separating what is known and what is unsubstantiated is not easy, but it's worth the effort. Maybe someday soon, we'll have a much better understanding about this mysterious condition.
To find out more about CFS, go to www.cdc.gov/cfs/.
Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.