Objective: Major depressive disorder (MDD) has been associated with hypercortisolism, reduced glucocorticoid feedback sensitivity, and impaired memory function. In healthy subjects, administration of hydrocortisone impairs declarative memory. The aim of this study was to examine the effects of acute hydrocortisone administration on memory retrieval in MDD patients and healthy controls. We further tested whether the enhancing or impairing effects of hydrocortisone would prevail when it was given after encoding and when delayed retrieval was tested at a time point when glucocorticoid levels were still elevated.
Method: In a placebo-controlled, double-blind crossover study, 44 patients with DSM-IV MDD and 51 healthy control participants received either placebo or 10 mg of hydrocortisone orally before memory testing. A word list paradigm and the Logical Memory Test from the Wechsler Memory Scale were applied. The study was conducted from April 2008 until April 2010 at sites in Bielefeld and Hamburg, Germany.
Results: In both memory tests, patients with MDD performed worse than controls. Healthy controls showed impaired memory performance after hydrocortisone administration compared to placebo. In contrast, hydrocortisone had no effects on memory in MDD patients. Furthermore, in healthy controls we found that administration of hydrocortisone immediately after learning did not lead to an enhanced free recall during increased cortisol levels.
Conclusions: It appears that the impairing effects of hydrocortisone on memory performance are missing in patients with MDD. This might be interpreted in the context of reduced central glucocorticoid receptor functioning.
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