Preliminary evidence that glucose ingestion facilitates prospective memory performance

Previous research has found that the ingestion of glucose boosts task performance in the memory domain (including tasks tapping episodic, semantic, and working memory). The present pilot study tested the hypothesis that glucose ingestion would enhance performance on a test of prospective memory. In a between-subjects design, 56 adults ranging from 17 to 80 years of age performed a computerized prospective memory task and an attention (filler) task after 25 g of glucose or a sweetness-matched placebo. Blood glucose measurements were also taken to assess the impact of individual differences on glucose regulation. After the drink containing glucose, cognitive facilitation was observed on the prospective memory task after excluding subjects with impaired fasting glucose level. Specifically, subjects receiving glucose were 19% more accurate than subjects receiving a placebo, a trend that was marginally nonsignificant, F1,41 = 3.4, P = .07, but that had a medium effect size, d = 0.58. Subjects receiving glucose were also significantly faster on the prospective memory task, F1,35 = 4.8, P < .05, d = 0.6. In addition, elevated baseline blood glucose (indicative of poor glucose regulation) was associated with slower prospective memory responding, F1, 35 = 4.4, P < .05, d = 0.57. These data add to the growing body of evidence suggesting that both memory and executive functioning can benefit from the increased provision of glucose to the brain.