Updated

Helping chronic fatigue syndrome patients to push their limits and try to overcome the condition produces a better rate of recovery than getting them to accept the illness and adapt to a limited life, new research has found.

British researchers conducted the largest trial to date of people with the mysterious and debilitating condition, also known as ME, and found that up to 60 percent of patients improved if therapists encouraged them gradually to do more.

By contrast, patients whose therapists encouraged them to accept the limits of their illness and adapt their lifestyles to live with it showed significantly less improvement when they were followed up after 24 and 52 weeks.

Chronic fatigue syndrome (CFS) is a long-term debilitating condition of disabling physical and mental fatigue, poor concentration and memory, disturbed sleep and muscle and joint pain. It also known as myalgic encephalomyelitis (ME) and affects around 17 million people worldwide.

There is no cure for CSF/ME and scientists don't know what causes it. 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 recent scientific paper to have been based on contaminated samples in a lab.

There is also controversy about what kinds of treatments should be given, with some patients reluctant to accept that psychotherapies might help.

Some patient groups in Britain, where more than a quarter of a million people are estimated to have CFS/ME, have expressed concern that treatments like cognitive behavior therapy (CBT) that encourage patients to try to overcome or push the limits of their condition may even be harmful.

But in this study, which involved 640 patients in Britain, researchers found that CBT and another therapy called gradual exercise therapy (GET) were far more successful than adaptive pacing therapy (APT), in which the patient tries only to match activity levels to the amount of energy they have.

"It is very encouraging that we have found not one but two treatments that are similarly helpful to patients," said Trudie Chalder from King's College London, who worked on the study and published its findings in the Lancet medical journal on Friday.

All patients in the trial received specialist medical care which included advice about managing the illness and prescribed medicines for symptoms such as insomnia and pain.

The success of the added therapies was measured by patient ratings of fatigue, physical function, overall health and the ability to lead a normal life, plus tests of how far the patient could walk in six minutes, and of sleep, mood and fatigue levels after exertion.

The results showed that CBT and GET benefited up to 60 percent of patients, and around 30 percent of patients in each of these treatment groups said their energy levels and ability to function and returned to near normal levels.

External experts commenting on the study said its design was robust and its findings important.

"This study..matters a lot. CFS/ME is common, and causes a lot of suffering," said Professor Willie Hamilton of Britain's Peninsula College of Medicine and Dentistry. "I now know what to suggest to my patients."