I was however struck not by the overlaps with muscle disorders but with some of the symptoms that I had seen in depressed patients before I came to Queen Square. It dawned on me that I had a wonderful opportunity to test this out, since one thing that the Square was not short of was people with well characterised neuromuscular disorders. So I decided to carry out a simple clinical study, comparing the pattern of fatigue and fatigability in the CFS patients compared with those with illnesses such as myasthenia gravis. I enlisted the help of Robin Powell, another psychiatric trainee, to recruit a second control series of patients with major depression who were being treated at the Royal Free Hospital London.
There was no instrument available to measure subjective fatigue, so I simply invented one, which would later get modified into the Chalder Fatigue Scale, which also became a citation ‘hit’. And basically that was that.
What we showed was clear. The pattern of fatigue in the CFS patients was different to that seen in those with peripheral neuromuscular diseases, and instead was similar to those in the affective controls. The only time when the neuromuscular patients did look like the ME patients was when the former group also had comorbid depression. But there were also differences between the ME patients and the depressed control group that Robin had recruited, although these differences were not as great as those between the CFS patients and those with myasthenia. The CFS patients did not show core cognitive features of depression, such as guilt or self blame. We wondered if this was a reflection of their different pattern of attribution (blaming an external cause, namely a virus, rather than an internal cause, as the depressed patients did). Overall, however, our principal conclusion was that the fatigue in the ‘chronic postviral fatigue’ patients (as we labelled them, knowing that ME would be unacceptable to the journal) had a central, not peripheral, origin, and that primary muscle disease was therefore an unlikely explanation for the symptoms and disability that the patients showed.
No wonder it's a pile of doo-dah (or s**t if you prefer). Chalder is a piece of work too. 
. This man's ego knows no bounds - he is completely happy to re-frame any neuro-medical condition - regardless of scientific evidence to the contrary or his own lack of professional expertise in it - to suit his own narrative and agenda, muddying the waters in the process. It appears that he wants to expand the domain of psychiatry to subsume neurological conditions (but not vice versa). Just because a particular neurological condition may cause additional problems in patients that may be helped by behavioural interventions, doesn't therefore make it a 'psychiatric disorder'.
