Predicting Who Will Get Chronic Fatigue

Medically Reviewed by Jacqueline Brooks, MBBCH, MRCPsych
From the WebMD Archives

Dec. 7, 2001 -- Unraveling the mystery behind chronic fatigue syndrome continues to come in baby steps. The latest study shows that a blood test and physical fitness may predict who goes on to develop this puzzling problem.

Peter D. White and colleagues have shown in previous studies that certain infections -- especially mononucleosis or "mono" -- can trigger chronic fatigue syndrome (CFS) in certain people. But figuring out the reason has been a challenge.

The researchers took the next step toward discovering the link between mononucleosis infection and CFS by looking at 250 people who had either mono or your average viral upper respiratory infection. They studied them for six months after their infection was diagnosed.

The researchers found that what seems to be linked to CFS depends on how you define the disease. But when depression and anxiety were taken out of the definition, having mono definitely played a big role. Those with a positive mono blood test were twice as likely to come down with CFS.

But why do some people with mono develop CFS and not others?

The researchers looked at many variables including the speed with which CFS came on, antibiotics or other medications taken after the initial infection, how many friends and confidants the infected person had, and multiple blood tests. But none of these seemed to play a role.

In addition to having had mono, the only factor that seemed to make much of a difference to whether someone developed CFS was physical fitness. People with a lower level of physical activity within the months following the initial infection were much more likely to develop CFS.

The physical activity finding is a bit hard to decipher since having CFS may make you less likely to be active in the first place. However, the other possibility is that increasing your physical activity during the months following a mono infection might help beat CFS.

Contrary to other studies, these researchers did not find that having depression or anxiety before becoming infected with mono increased the chance of developing CFS.

"The particular virus causing the infection and the body's immune reaction to it may play an early role, but physical deconditioning may also be important," White says in a news release.

"The study also implies that CFS after infectious mononucleosis might be partially prevented or treated with an early and graded return to appropriate physical activity in order to prevent or treat physical deconditioning," he adds.