Dose-dependent action of glucose on memory processes in women: effect on serial position and recall priority

Previous research has shown that glucose can enhance memory in animals and humans. In humans, the facilitative effect of glucose is best observed with declarative memory tasks in older subjects. While the memory-enhancing action of glucose is well established, the underlying physiological mechanisms and the specific aspects of memory that are modulated by glucose in humans are not well understood. The present study sought to examine the effects of glucose on memory in young women using a memory paradigm sensitive to specific encoding and retrieval strategies. The glucose dose was adjusted for the weight of each participant in order to generate a dose response curve covering most doses used in previous studies. The results showed that 300 mg/kg glucose enhanced the primacy effect as defined by the recall of the first five items of the lists. However, none of the doses of glucose produced changes in the recall priority given to primacy items. The effect of glucose appears to be localized on the recall primacy effect, suggesting that glucose acts on precise memory operations. This improvement, however, is independent of the order in which subjects recalled the words. Cholinergic drugs have been shown to alter the recall of the primacy part of word lists and this observation is consistent with the hypothesis that glucose acts on memory through an interaction with brain cholinergic systems.