We don't know what causes CFS, a number of different theories and models have been put forward but we are not yet able to attribute CFS to a single cause. It
may be that CFS has more than one cause or that what we term CFS is actually a group of separate and distinct conditions.
There is also some dispute as to whether the cause is physical, viral or neurological or a combination of all three.
The following (not necessarily exclusive) possibilities have been put forward as explanations of the occurrence of CFS-
- CFS is an umbrella term for several different illnesses.
- One (or more) "core" disorder(s)
- Several different causative factors trigger a common disease process.
- The cause and/or pathophysiology are multifactorial.
- Certain factors are necesssary but not sufficient to cause CFS.
- Certain factors can infuence individual manifestations or duration.
- Some features are "downstream" consequences of the primary disease process.
Listed below are a number of possible triggers for CFS as identified by the Working Group report in 2002:
- Infections.10% of cases of glandular fever, viral meningitis and viral hepatitis are followed by CFS. CFS can follow infections with herpes, entero
viruses and hepatitis viruses.It is thought that infuenza and 'flu-like infections can also trigger CFS.
- There is some evidence to suggest that CFS may have occurred after immunisation.
- There is evidence to indicate that increased levels of stress have accompanied the onset of CFS. It is not yet known whether this is a causal
link or not. What is known is that periods of stress can trigger a setback in someone who already has CFS.
- Cases of CFS following physical trauma and surgery have been noted.
Listed here are a number of possible causes for CFS:
- Initailly CFS was thought to be caused by a virus infection, the Epstein Barr Virus was thought to be the most likely choice. However the American
Centers for Disease Control and Prevention have been unable to find a link between CFS and a wide variety of human pathogens, including the Epstein-Barr
virus. This does not preclude the possibility that viruses of infection may play a contributory factor if CFS has multiple causes instead of just one.
- It has been proposed that CFS is the result of an immunologic dysfunction. However, no tissue damage that is normally associated with autoimmune
disease has been found in CFS patients nor has there been an increased risk of cancer and opportunistic infections.
- Some studies have found a lower number
of killer cells in CFS patients whereas others have found no difference at all between those with CFS and the general population.
- Tests on the spinal cord fluid of those people with CFS and related conditions have found 16 proteins which were missing from the control group. This
would seem to concur with the World Health Organisation's classification of CFS as a neurological disorder.
- Many people with CFS feel dizzy, faint or nauseous when they stand up. This is thought to be the result of a reduced blood flow to the brain. It is felt that
this shows that the autonomic nervous system has been disrupted in some way.
- It is felt that damage to the reticular activating system (which is connected with sleep function) may be responsible for at
least some cases of CFS.
- Some cases of CFS are mistakenly attributed to depression. The main difference is that people with clinical depression respond well to physical exercise
whereas people with CFS have exercise intolerance. some people with CFS are also depressed but many are not which would suggest that depression is not a causal
factor.
- A more traditional view is that CFS is a complex psychsomatic disorder (ie an illness whose symptoms are caused by mental processes of the sufferer
rather than any immediate physiological cause) which is caused by chronic stress.
- There is some evidence to suggest a causal link between stress or trauma and the development of CFS. One study has found that both stress and emotional
instability are significant risk factors. If stress does play a role then we do not yet understand how this contributes to the development of the illness
nor can we explain the huge numbers of people who experience high levels of stress but do not go on to develop CFS.
- Oxidative stress has been shown in some studies to be a factor in fatigue,
pain, postexertional malaise and exercise intolerance.
It is felt that the immune system has some role to play in the development of CFS, there is also evidence to suggest that CFS patients have both
over and under expression of genes involved in the immune system.
