This is a draft, please feel free to correct me in the discussion... What exactly is Chronic Fatigue Syndrome (CFS)? That depends on how you define it. Around the world different researchers and doctors use very different definitions. The most simple definition only requires the patient to be able to say that he/she has been "tired" for a period of six months. Naturally this definition encorporates a large fraction of society with many different underlying causes - it is therefore not useful to reseachers who are trying to study a single disease. Some definitions overcome this problem by requiring that a range of additional symptoms be present. Other definitions require biomedical abnormalities to be measured. Can you summarise for me the main controversy surrounding CFS? Some doctors maintain that CFS is a psychological disorder that is treatable with counselling and exercise. The main point of contention by patient advocates is that, while this may be true for some people diagnosed with CFS, it isn't true for everyone. Indeed there is a large subset of CFS patients who exhibit a large range of reproducible biological abnormalities that do not respond to councilling and are often made worse by exercise. Patient advocates insist that these patients should receive biomedical treatment specific to their condition. My doctor says that exercise therapy and councilling have been proven as working treatments for CFS. Is this true? Yes and no. Most research psychiatrists use a broad definition for CFS that encompasses people suffering from depression. They are then able to show that some patients within that broad group respond well to counselling and exercise therapy. Other studies using a different set of patients have shown that there is no measurable improvement. One study indicated that placebo was a better treatment. What has never been shown is that all patients respond well. Groups of patients that satisfy narrower defintions of the disease (and have many other symptoms in addition to fatigue) including common measurable biological abnormalities have never been used in psychiatric studies. What is meant by "biomedical"? Biomedical is a term used in medicine to indicate that something is physical in origin (as opposed to psychological). My friend was diagnosed with CFS and recovered after trying councelling/exercising/improving their diet etc. So why shouldn't all patients be able to benefit in a similar way? The definition of CFS most frequently used contains people with more than one illness. Thus what works for someone may not necessarily work for everyone. What is the difference between CFS and ME? Again this depends on definition. Originally, ME was characterised by many of the symptoms of CFS in addition to the identification of brain abnormalities as observed with a special brain scan (known as SPECT scan). Over time ME (along with other illnesses) was gradually merged in with CFS to form the composite term CFS/ME. These days, the actual diagnosis depends entirely on the diagnosing physician. Can you summarise the main biomedical abnormalities that have been observed in patients with CFS?