Deficits in hippocampus-mediated Pavlovian conditioning in endogenous hypercortisolism.
BACKGROUND
Elevated endogenous levels of corticosteroids cause neural dysfunction and loss, especially within the hippocampus, as well as cognitive impairment in hippocampus-mediated tasks. Because Cushing's syndrome patients suffer from hypercortisolism, they represent a unique opportunity to study the impact of elevated glucocorticoids on cognitive functions. The aim of this study was to examine the performance of Cushing's syndrome patients on trace eyeblink conditioning, a cross-species, hippocampal-mediated test of learning and memory.


METHODS
Eleven Cushing's syndrome patients and 11 healthy control subjects participated in an eyeblink trace conditioning test (1000-msec trace) and a task of declarative memory for words. Salivary cortisol was collected in both the patients and the control subjects, and urinary free cortisol was collected in the patients only.


RESULTS
The patients exhibited fewer conditional responses and remembered fewer words, compared with the control subjects. Cortisol levels correlated with immediate and delayed declarative memory only. Conditional response correlated with delayed recall after controlling for the magnitude of unconditional response.


CONCLUSIONS
The integrity of the hippocampus seems to be compromised in Cushing's syndrome patients. Trace eyeblink conditioning might be useful both as a clinical tool to examine changes in hippocampus function in Cushing's disease patients and as a translational tool of research on the impact of chronic exposure of glucocorticoids.
Grillon
Christian
C
Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD 20892-2670, USA. Grillon.christian@nih.gov
Smith
Kathryn
K
Haynos
Ann
A
Nieman
Lynnette K
LK
D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D003214:Conditioning, Classical / Q000502:physiology*; D003480:Cushing Syndrome / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006624:Hippocampus / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000652:urine; D008297:Male; D008569:Memory Disorders / Q000378:metabolism / Q000503:physiopathology; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D012043:Regression, Psychology; D012463:Saliva / Q000378:metabolism; D013997:Time Factors; D014706:Verbal Learning / Q000502:physiology
D006854:Hydrocortisone