Chronic Fatigue Syndrome Health Article

Definition

Chronic fatigue syndrome (CFS) is a condition that causes extreme tiredness. People with CFS have debilitating fatigue that lasts for six months or longer. CFS does not have a known cause, but appears to result from a combination of factors.

Description

CFS is the most common name for this disorder, but it also has been called chronic fatigue and immune disorder syndrome (CFIDS), myalgic encephalomyelitis, low natural killer cell disease, post-viral fatigue syndrome, Epstein-Barr disease, and yuppie flu. Reports of a CFS-like syndrome called neurasthenia date back to 1869. Later, people with similar symptoms were said to have fibromyalgia because one of the main symptoms is myalgia, or muscle pain. Because of the similarity of symptoms, fibromyalgia and CFS are considered to be overlapping syndromes.

In the early to mid-1980s, there were outbreaks of CFS in some areas of the United States. Although many CFS patients had high levels of antibodies to the Epstein-Barr virus (EBV), which causes mononucleosis, many healthy people also had high levels of EBV antibodies. Scientists have also found high levels of other viral antibodies in the blood of CFS patients. These findings have led many scientists to believe that a virus or combination of viruses may trigger CFS.

Although CFS can affect people of any gender, age, race, or socioeconomic group, most patients diagnosed with CFS are 25–45 years old and female. Estimates of how many people are afflicted with CFS vary due to the similarity of CFS symptoms to other diseases and the difficulty in identifying it. The Centers for Disease Control and Prevention (CDC) has estimated that 4–10 people per 100,000 in the United States have CFS. According to the CFIDS Foundation, about 500,000 adults in the United States (0.3% of the population) have CFS. This probably is a low estimate since these figures do not include children and are based on the CDC definition of CFS, which is very strict for research purposes.

Causes & symptoms

There is no single known cause for CFS. Studies have pointed to several different conditions that might be responsible. These include:

• viral infections
• chemical toxins
• allergies
• immune abnormalities
• psychological disorders

Many doctors and researchers think that CFS may not be a single illness but a group of symptoms caused by several conditions. One theory is that a microorganism, such as a virus, or a chemical injures the body and damages the immune system, allowing dormant viruses to become active. When these viruses start growing again, the immune system may overreact and produce chemicals called cytokines that can cause flu-like symptoms. Immune abnormalities have been found in studies

of people with CFS, although the same abnormalities are also found in people with allergies, autoimmune diseases, cancer, and other disorders.

In late 2001, a panel of experts convened and concluded that a virus or bacteria acting on the immune system may indeed cause CFS and the experts agreed that the published evidence is now substantial enough to prove that the immune system is involved in CFS. They said infections may also play a role in the condition, but have still not identified one single agent common to all patients with CFS and they have encouraged further research. The panel also concluded that reproductive hormones may play a role in the condition, which might explain a higher prevalence among women.

The role of psychological problems in CFS is very controversial. Because many people with CFS are diagnosed with depression and other psychiatric disorders, some experts conclude that the symptoms of CFS are psychological. However, many people with CFS did not have psychological disorders before getting the illness. Many doctors think that patients become depressed or anxious because of the effects of the symptoms of their CFS. One recent study concluded that depression was the result of CFS, not its cause.

People with CFS have severe fatigue that keeps them from performing their normal daily activities. They may have sleep disturbances that keep them from getting enough rest or they may sleep too much. When they exercise or try to be active in spite of their fatigue, people with CFS experience debilitating exhaustion that can confine them to bed for days.

Other symptoms of CFS include:

• muscle pain (myalgia)
• joint pain (arthralgia)
• sore throat
• headache
• fever and chills
• tender lymph nodes
• trouble concentrating
• memory loss

A recent study at Johns Hopkins University found an abnormality in blood pressure regulation in 22 of 23 patients with CFS. This abnormality, called neurally mediated hypotension, causes a sudden drop in blood pressure when a person has been standing, exercising, or exposed to heat for a while. When this occurs, patients feel lightheaded and may faint. They often are exhausted for hours to days after one of these episodes. When treated with salt and medications to stabilize blood pressure, many patients in the study had marked improvements in their CFS symptoms.