Ghrelin does not act as a short-term cognitive enhancer in young male humans

Due to its dual role in appetite and memory-related processes, a function of ghrelin in memory for food-location associations has been suggested. Here we show in a double-blind randomized crossover design that acute administration of ghrelin does not enhance memory function in humans. Twenty-one healthy young male participants had to memorize food- and nonfood-related words presented on a background of a virtual navigational route while undergoing fMRI recordings. Acyl ghrelin or placebo was administered between two runs of this task, thereby testing both encoding and consolidation in a retrieval session after 24 hours. Neither in this spatial-verbal learning task, nor in a subsequently performed cognitive test battery comprising tests for working memory, fluid intelligence, perceptual speed, creativity, and psychomotor vigilance, any differences between conditions could be observed. In conclusion, in contrast to several animal models, ghrelin does not act as a short-term cognitive enhancer in humans.