MEDICAL NEWS:

February 13, 2008 — People who suffer from chronic fatigue syndrome (CFS) often endure months of persistent fatigue, muscle pain, and impaired memory and concentration. Understanding the physiological changes that accompany CFS, however, has been difficult, but a new study accepted for publication in the Journal of Clinical Endocrinology & Metabolism (JCEM) reveals that abnormally low morning concentrations of the hormone cortisol may be correlated with more severe fatigue in CFS patients, especially in women.

"We're learning more and more about the complexities of the illness that is chronic fatigue syndrome," said William C. Reeves, M.D., with the Centers for Disease Control and Prevention in Atlanta, Ga., and lead author of the study. "This research helps us draw a clearer picture in regards to how CFS affects people, which ultimately will lead to more effective management of patients with CFS."

For their study, the researchers screened 19,381 residents of Georgia, selecting 292 people who had CFS, 268 who were considered chronically unwell, and 163 who were considered well to participate. The researchers then measured free cortisol concentrations in saliva, which was collected on regular workdays, immediately upon awaking and 30 minutes and 60 minutes after awakening. The data indicated different profiles of cortisol concentrations over time among the groups, with the CFS group showing an attenuated morning cortisol profile.

Study participants were purposely screened and enrolled from the community, rather than from volunteers identified at a specialty referral clinic. The purpose of this study design was to provide results that would be more generalizable to the population suffering from CFS. In this study, women with CFS exhibited significantly attenuated morning cortisol profiles compared with well women. In contrast, men with and without CFS showed no difference in cortisol levels. This could explain why women are predominately more likely to suffer from CFS.

This study confirms previous research indicating that CFS is related to an imbalance in the normal interactions among the various systems of the body that work together to manage stress. "People with CFS have reduced overall cortisol output within the first hour after they wake up in the morning, which is actually one of the most stressful times for the body," Dr. Reeves said. "We need further studies to better understand the relationship between morning cortisol levels and functional status of a patient suffering from CFS."

Other researchers involved in this study include Drs. Urs M. Nater, Elizabeth Maloney, Roumiana S. Boneva, Brian M. Gurbaxani, Jin-Man Lin and James F. Jones with the Centers of Disease Control and Prevention; and Dr. Christine Heim with the Emory School of Medicine in Atlanta.