Glucose facilitation of cognitive performance in healthy young adults: examination of the influence of fast-duration, time of day and pre-consumptionplasma glucose levels

Rationale: Previous investigations have demonstrated increased performance after the administration of a glucose-load on certain aspects of cognitive functioning in healthy young adults. Generally these studies have used a pr ocedure where participants were tested in the morning after an overnight fa st. Objective: The aim of the present study was, for the first time, to inv estigate the glucose cognitive facilitation effect under more natural testi ng times and with shorter duration of the previous fast. Methods: Measures of verbal and non-verbal memory performance were compared under different f asting intervals (2-h fast versus overnight fast), times (morning versus af ternoon) and glycaemic conditions (glucose versus aspartame drinks) in heal thy young participants. Results: There was a significant glucose facilitati on effect on long-term verbal memory performance. In addition, glucose sign ificantly enhanced long-term spatial memory performance. The effect of gluc ose was essentially equivalent whether it was given after an overnight fast or a 2-h fast following breakfast or lunch. There was no effect of drink a nd time of day on working memory performance. Conclusions: The results of t his study further support the hypothesis that glucose administration can en hance certain aspects of memory performance in healthy young adults. More s ignificantly, the findings indicate that this cognitive facilitation effect persists under more naturalistic conditions of glucose administration and is not restricted to long fast durations or morning administration.