To make matters worse, some people with fibromyalgia also suffer from chronic fatigue and immune dysfunction syndrome, or CFIDS. It isn't easy to always distinguish one condition from the other. Some people with fibro may have symptoms of CFIDS, while others with CFIDS may experience the pains of fibromyalgia. The two conditions also share many other overlapping conditions, such as irritable bowel syndrome, depression, and cognitive dysfunction.

People who have CFIDS suffer from debilitating exhaustion and extremely poor stamina. They have problems with memory and concentration and often experience flu-like symptoms as well. One of the telling signs of CFIDS is how you fare after even the slightest exertion. Within twelve to forty-eight hours of any sort of physical or mental exertion, people with CFIDS typically experience a worsening of their symptoms and require an abnormally long period of time to recover.

Getting diagnosed with CFIDS isn't easy. To make matters worse, there are no blood tests, X-rays, or diagnostic markers that can help determine whether you have CFIDs. Instead, diagnosis depends on the patient's self-reported symptoms. For a list of criteria, see Chapter 3.

Anyone can get CFIDS, but the condition is three times more common in women than it is in men. In women, it is more common than multiple sclerosis, lupus, HIV infection, and lung cancer. It can also occur, albeit rarely, in children and adolescents. In all, an estimated 800,000 people in the United States suffer from this mysterious condition.

Like fibromyalgia, no one knows exactly what causes CFIDS. But many people report the onset of symptoms shortly after a flu-like illness.

Could It Be a Virus?

In its earliest stages, CFIDS resembles the flu, with aches, fever, and chills accompanying the fatigue. These symptoms have prompted many scientists to question whether a virus is the infectious agent that triggers CFIDS.

In the 1980s, researchers thought CFIDS was brought on by the Epstein-Barr virus, the culprit behind the yuppie flu, only to later discount that idea after antibodies to the virus turned up in healthy people, too. Some scientists have since thought that CFIDS was the result of other viruses, such as the human herpesvirus6, a common virus that has been linked to multiple sclerosis and that lies dormant until reawakened. But that connection has not been firmly established in CFIDS.

Other microorganisms that have been suspected of causing CFIDS include mycoplasmas, a form of bacteria best known for causing walking pneumonia. Viruses linked to Coxsackie virus and polio have also come under scrutiny. But so far, researchers can find no solid evidence that CFIDS is caused by a specific virus.

Immune System Problems

Although no particular immune dysfunction has been singled out in people with CFIDS, research suggests that there may be abnormalities in the immune system that contribute to the symptoms. In most cases, the immune system of people with CFIDS appears to be weaker. A large percentage of people with CFIDS have also been found to carry autoantibodies, which suggests that CFIDS may be an autoimmune disorder.

Autonomic Nervous System (ANS)

The part of the central nervous system that controls your body's involuntary functions — such as heart rate, breathing, and digestion — may be faulty in people who have CFIDS. Studies have shown that people with CFIDS have trouble regulating blood pressure and are particularly susceptible to low blood pressure. Research has found that CFIDS sufferers are likely to faint when their bodies are tilted at a 60-degree angle.

Another indicator of a link to the ANS is that a large number of people who have CFIDS also have orthostatic intolerance, an ANS-related condition in which changes in posture also cause dramatic changes in heart rate and blood pressure. The result is often dizziness upon standing and sometimes even fainting.

Too Many Cytokines

In people who have CFIDS, there appears to be an imbalance of cytokines, proteins produced by white blood cells that help regulate immune function. Many people with CFIDS have elevated levels of interleukin-1-alpha (IL-1 alpha), a type of cytokine that promotes inflammation. IL-1 is the same cytokine that causes the inflammation seen in rheumatoid arthritis. Other cytokines cause fatigue, which is why all you want to do when you're sick is lie in bed.

Thyroid Troubles

Many people who have fibromyalgia or CFIDS resemble patients with hypothyroidism. They're sluggish, slow, and prone to weight gain. They lack any energy and crave sleep. And yet tests show that their thyroids are functioning fine. Some doctors believe that people with CFIDS or fibromyalgia have an abnormally low metabolism. Although the thyroid is churning out the right amount of hormones, the body is unable to recognize them. Since thyroid hormone increases metabolism, this malfunction results in less energy in the body cells.

Adenosine Triphosphate (ATP) Shortage

Some experts believe that people with CFIDS or fibromyalgia have a shortage of adenosine triphosphate (ATP). ATP, the body's primary source of fuel, is produced in the mitochondria of body cells. All carbohydrates, proteins, and fats from food are converted into ATP. When there is enough oxygen in supply, more ATP can be produced. But when oxygen is limited, the normal mechanism shuts off, and the body switches to a process called anaerobic glycolysis, which produces considerably less ATP and more undesirable byproducts. Think of the burning feeling you get when you're working a muscle really hard. That burn comes from the release of acids caused by anaerobic glycolysis. Experts believe that people with fibromyalgia have less oxygen in their muscles and reduced capacity for ATP production. The result? Fatigue.