Any ideas as to why there is such a lack of correlation between symptoms / debilitation and detectability of the disease by scientists / doctors ? for example how some that can barely even leave their bed but it does not show on a standard blood test ?
This discrepancy between the severity of symptoms and the lack of finding anything amiss in normal blood or tissue tests is a characteristic of ME/CFS, and of a number of other diseases, which are collectively called
functional disorders. This contrasts to diseases labelled
structural disorders, in which there are clear visually or physically observable abnormalities (eg, a build up of plaque in the brain of Alzheimer's patients).
Patients understandably don't like the name functional disorder, because some psychiatrists and psychologists have exploited the lack of finding anything structurally wrong in the blood or tissues, and come up with their lazy and crackpot theories that functional disorders must be psychologically caused, and "all in the mind". Which is complete nonsense, but it keeps certain none-too-bright shrinks in employment.
However, in terms of understanding causes, the name "functional disorder' is a good one, because it indicates exactly where the etiology of the disease lies: the cause lies in problems with the
functioning of the body, rather that in problems with the
structure of the body. And that's why in functional disorders, the cause is not detected by normal visual or physical examination, because there is not much wrong structurally.
For example, if you consider multiple sclerosis, this can be classed as a structural disorder, because under a microscope you can see the lesions in myelin sheath of the nerves, and it is then immediately apparently why the nerves cannot function properly in MS.
But you generally don't find any structural pathologies in ME/CFS (although some severe cases do sometimes show a few brain lesions). So it is assumed that the cause of ME/CFS must be functional, meaning there must be problems with the way that the body operates.
One excellent candidate for the functional cause of ME/CFS is autoimmune attack. If your immune system is creating antibodies that attack and disrupt the micro-machinery inside your cells, and antibodies which attack and disrupt receptors on the cells which receive signals, you will generally not see any of that going on under the microscope, and nothing will look visually and structurally wrong, yet such an autoimmune attack may be profoundly altering the
functioning of the body, and thereby causing severe disease.