Chronic fatigue syndrome affects more people than once believed, CDC finds

The number of Americans living with chronic fatigue syndrome is beginning to become more clear. 

An estimated 3.3 million U.S. adults have the disorder, which affects multiple body systems and causes severe exhaustion, according to a report from the U.S. Centers for Disease Control and Prevention. Women are more likely than men to have chronic fatigue syndrome, and the percentage of adults with disorder increases until age 70, when it then declines.

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The CDC report used data from the National Health Interview Survey, which asked 57,000 adults whether a health care professional had ever diagnosed them with chronic fatigue syndrome and whether they still have it. About 1.3% answered yes to both questions, which translates to about 3.3 million Americans, according the CDC. 

And that means chronic fatigue syndrome "is not a rare illness," the CDC's Dr. Elizabeth Unger, one of the study's authors, told the Associated Press.

The CDC's estimate may be an undercount, because some health experts believe only a portion of the people with chronic fatigue syndrome are actually diagnosed, the study notes. 

"It's never, in the U.S., become a clinically popular diagnosis to give because there's no drugs approved for it," Daniel Clauw, director of the University of Michigan's Chronic Pain and Fatigue Research Center, told the AP. "There's no treatment guidelines for it."

The CDC estimate also likely includes some patients suffering from prolonged exhaustion caused by long COVID – lingering symptoms from an acute COVID-19 infection. The symptoms caused by the conditions can differ, but some people with long COVID experience symptoms similar to chronic fatigue syndrome.

Here's what to know about chronic fatigue syndrome:

What causes chronic fatigue syndrome?

Chronic fatigue syndrome, also known as myalgic encephalomyelitis, causes extreme fatigue that lasts for at least six months, according to the Mayo Clinic. It often hinders people from engaging in their daily activities or confines them to bed. Symptoms worsen with physical or mental activity and don't completely improve with rest. 

Experts have yet to identify a cause for chronic fatigue syndrome. Possible causes being studied by scientists include infections, immune system changes, stress that affects body chemistry, changes in energy production and genetic links, according to the CDC.

What are the symptoms and how is it diagnosed?

Chronic fatigue syndrome can be unpredictable, because symptoms may come and go, or change in severity over time. 

According to the CDC, the core symptoms required for a chronic fatigue syndrome diagnosis include:

• A greatly reduced ability to do activities that were usual before the illness. This dropoff must occur along with fatigue and persist for at least six months.
• Post-exertional malaise, the worsening of chronic fatigue symptoms after physical or mental activity that would not have caused a problem before the illness. Some patients describe this as a "crash" or "relapse."
• Sleep problems, such as not feeling less tired after a full night of sleep or having trouble falling or staying asleep.

Other symptoms used to diagnose chronic fatigue syndrome include problems with thinking and orthostatic intolerance, which is the worsening of symptoms while standing or sitting upright. People with chronic fatigue syndrome also may experience muscle or joint pain, headaches, sore throat, digestive issues, shortness of breath and irregular heartbeat.

Even if symptoms are present, chronic fatigue syndrome is difficult to diagnose since there is no test to confirm it and it appears similar to many other illnesses. 

How is chronic fatigue syndrome treated?

There is no treatment or cure approved by the U.S. Food and Drug Administration. But some symptoms can be treated or managed using medications or therapies. Doctors work with patients and their families to isolate the symptom that causes the most problems and then treat that symptom first. Health care providers can help address sleep, pain, dizziness and concentration problems. 

Other strategies include professional counseling, eating a balanced diet, nutritional supplements, gentle massage therapy or meditation.