Glucocorticoid receptor mediated negative feedback in chronic fatigue syndrome using the low dose (0.5 mg) dexamethasone suppression test.
BACKGROUND
Chronic fatigue syndrome (CFS) is associated with hypocortisolism, but it is not yet clear the extent to which enhanced negative feedback may underlie this finding.


METHODS
We undertook a low-dose dexamethasone (0.5 mg) suppression test in 18 CFS patients and 20 matched, healthy controls. We measured salivary cortisol levels at 0800 h, 1200 h, 1600 h and 2000 h before and after the administration of 0.5 mg of dexamethasone.


RESULTS
Basal cortisol output was raised in this group of CFS patients compared to controls. Overall, the percentage suppression following dexamethasone administration was no different between CFS (mean+/-sem: 80.4+/-4.4%) and controls (76.2+/-4.9 %). However, the sub-group of patients with CFS and comorbid depression (n=9) showed a significant hypersuppression of salivary cortisol in response to dexamethasone (89.0+/-1.9%; p<0.05 v controls).


CONCLUSIONS
The sub-group analysis was on small numbers and should be considered preliminary. Dexamethasone probes only glucocorticoid medicated negative feedback but does not probe mineralocorticoid feedback, the other main physiological feedback mechanism.


CONCLUSIONS
We found partial support for the hypothesis of enhanced negative feedback in CFS but only in patients with comorbid depression and also in the context of a sample of patients with elevated basal cortisol levels, which is an atypical finding in the literature.
King's College London, Institute of Psychiatry, Section of Neurobiology of Mood Disorders, Division of Psychological Medicine, London SE5 8AF, United Kingdom.
Andrew
A
Papadopoulos
Marcel
M
Ebrecht
Amanda D L
AD
Roberts
Lucia
L
Poon
Nicolas
N
Rohleder
Anthony J
AJ
Cleare
D000293:Adolescent; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D015897:Comorbidity; D035061:Control Groups; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D003907:Dexamethasone; D039721:Diagnostic and Statistical Manual of Mental Disorders; D015673:Fatigue Syndrome, Chronic / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D011569:Psychiatric Status Rating Scales; D011965:Receptors, Glucocorticoid / Q000378:metabolism / Q000502:physiology*; D012463:Saliva / Q000737:chemistry*
D011965:Receptors, Glucocorticoid; D003907:Dexamethasone; D006854:Hydrocortisone