“ME/CFS is not synonymous with depression or other psychiatric illnesses. The belief by some that they are the same has caused much con- fusion in the past, and inappropriate treatment.
Nonpsychotic depression (major depression and dysthymia), anxiety disorders and somatization disorders are not diagnostically exclusionary, but may cause significant symptom overlap. Careful attention to the timing and correlation of symptoms, and a search for those characteristics of the symptoms that help to differentiate between diagnoses may be informative, e.g., exercise will tend to ameliorate depression whereas excessive exercise tends to have an adverse effect on ME/CFS patients.”