Causes

Theories abound about the causes of chronic fatigue syndrome. No primary cause has been found that explains all cases of CFS, and no blood tests or brain scans can definitively diagnose the condition.

Convergence of Factors. A number of experts believe that CFS develops from a convergence of conditions that may include the following:

• Viral or other infectious agents
• Genetic factors
• Brain abnormalities
• A hyper-reactive immune system
• Psychiatric or emotional conditions
• Stress-related hormonal abnormalities

Most patients report some moderate-to-serious physical illness (such as a chronic viral infection) or emotional event (like an episode of depression) before CFS. Some experts theorize that such events, alone or in combination, may interact with certain neurologic and genetic abnormalities to trigger CFS.

Still, it is not clear what sequence of events actually leads to the fatigue and other prominent symptoms of this disorder. Nor is there any specific brain or nervous system problem that experts can point to with assurance.

Infections

Because most of the features of CFS resemble those of a lingering viral illness, many researchers have focused on the possibility that a virus or some other infectious agent causes the syndrome in some cases.

Still, not all CFS patients show signs of infection. Although experts have long been divided on whether infections play any role in this disorder, subtypes of viral-related and non-viral CFS may both exist.

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Review Date: 01/10/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)