By Kate Kelland
LONDON (Reuters) - Helping patients with chronic fatigue syndrome to overcome their fears that exercise or activity will make their symptoms worse is one of the most important factors behind therapies that can make them better, scientists said on Wednesday.
Presenting an analysis on a trial showing how cognitive behavior therapy (CBT) and graded exercise therapy (GET) help reduce fatigue and improve physical function in people with chronic fatigue syndrome (CFS), the researchers said misguided but understandable fears about being active were key.
"You're not going to ask somebody who hasn't been going out or engaging in any exercise for several years to suddenly get on their bike -- you would want to do these things very gradually and carefully," Trudie Chalder of King's College London's Institute of Psychiatry told a briefing.
"(But) our results suggest that fearful beliefs can be changed by directly challenging such beliefs, or by simple behavior change with a graded approach."
CFS, sometimes called myalgic encephalomyelitis or ME, is a debilitating condition characterized by disabling physical and mental fatigue, poor concentration and memory, disturbed sleep and muscle and joint pain.
There is no cure and scientists don't know what causes it, but it affects around 17 million people worldwide.
Many sufferers say they think their illness started after a viral infection. But suggested links to a virus known as XMRV were shown in a scientific paper in 2010 to have been based on contaminated samples in a lab.
Calder worked on a 2011 study called the PACE trial. It found that CBT, where a health professional helps patients understand and change the way they respond to symptoms, and GET, a personalized, gradually increasing exercise program, helped around 60 percent of CFS patients improve.
In this latest study, Calder's team sought to find out how the treatments worked for some patients, with a view to allowing therapies to be improved or adapted to help more.
Of all the mediating factors analyzed, the researchers found the strongest -- accounting for up to 60 percent of the effect -- was reducing fears that exercise would make symptoms worse, something they described as "an understandable reaction to having CFS".
Professor Peter White of Queen Mary, University of London, who worked on Calder's team, stressed that neither this nor the original PACE study was able to find the root causes of CFS, but only to analyze how therapies can improve symptoms.
(Editing by Mark Heinrich)