Causes of chronic fatigue syndrome

Exactly what causes chronic fatigue syndrome (CFS) is unknown, but there are several theories.

Some experts think a viral infection such as Mononucleosis can trigger the condition. Certain bacteria have also been suggested as a cause of CFS in some people, including types ofbacteria responsible for pneumonia .

However, while tiredness is normal after a viral infection, this doesn't explain why symptoms persist and get worse in CFS. Also, many cases of CFS don't start after an infection, and this theory doesn't explain why the condition sometimes develops gradually.

Other suggested causes of CFS include:

• problems with the immune system
• a hormone imbalance
• psychiatric problems some cases have been linked to mental exhaustion, stress, depression and emotional trauma
• genes some people mayhave an inheritedtendency to develop CFS as it's more common in some families
• traumaticevents some cases have been linked to events such as surgery or a serious accident

It's possible CFS is caused by acombination of factors. Further research is necessary toconfirm whatcauses the condition.

Debate over classification

The World Health Organization (WHO) has classified CFS as a chronic (long-term) neurological condition and this classification has been accepted by the Department of Health. However, the WHO's decision remains controversial and isn't accepted by everyone working in the field.

Members of the team of health professionals who drew up theNational Institute of Health and Care Excellence (NICE) guidelines for CFS couldn't agree that this classification is the right decision, and 84% of members of the Association of British Neurologists surveyedin 2011 said they didn't view CFS as a neurological condition.