The Impact of Glucose Ingestion and Gluco-Regulatory Control on Cognitive Performance: a Comparison of Younger and Middle Aged Adults (original) (raw)
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Effects of glucose on memory processes in young adults
Psychopharmacologia, 1991
Recent studies suggest that glucose enhances memory in rodents and humans. The present experiment investigated the effects of glucose on memory performance and blood glucose changes in young adults (19-25 years). Subjects ingested (300 ml beverage) three doses of glucose (0, 30, 100 g) in a random, double-blind, triple crossover design. Thirty minutes post-glucose, subjects were shown nouns on a computer monitor and then administered recall and recognition memory tests. Blood samples were drawn at regular intervals. There was no effect of glucose on memory performance, and plasma glucose measures did not correlate with memory test scores. Statistical power was adequate to detect a medium effect. The results contradict the hypothesis that glucose enhances memory performance in young, healthy normal adults.
Preliminary evidence that glucose ingestion facilitates prospective memory performance
Nutrition Research, 2011
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, F 1,41 = 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, F 1,35 = 4.8, P b .05, d = 0.6. In addition, elevated baseline blood glucose (indicative of poor glucose regulation) was associated with slower prospective memory responding, F 1, 35 = 4.4, P b .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.
Behavioural Brain Research, 2002
Memory for a list of 20 words can be enhanced by preceding learning by consumption of 25 g of glucose, compared with consumption of an equally sweet aspartame solution (Psychopharmacology 137 (1998) 259; Psychopharmacology 157 (2001) 46). However, using this anterograde administration procedure, it is impossible to separate whether glucose affects encoding, consolidation, or retrieval. The present placebo-controlled, double-blind study investigated the effect of anterograde and retrograde administration on memory performance in healthy young participants. In order to evaluate whether post-acquisition administration of glucose can improve memory performance and to compare possible differences in the size of the effect, participants were administered 25 g of glucose immediately before or immediately after presentation of a word list. Moreover, in order to investigate whether the effect of glucose administration on memory performance is time-dependant, a third group received 25 g of glucose 15 min before learning the word list. Word-list recall was tested 30 min and 24 h after word list presentation. Measures of spatial memory performance and working memory were also evaluated. The results of this study showed that both pre-and postacquisition oral glucose administration (25 g) can improve memory performance. However, as the time interval between anterograde glucose administration and memory encoding increased, the glucose memory facilitation effect decreased. This study provides evidence that glucose enhances memory performance in healthy young people even when it is given after learning has taken place, and that this effect is observed at least up to 24 h after glucose administration. Moreover, it provides evidence that the effect of glucose on memory performance may be time-dependent, as the enhancement of retention was decreased when the administrationlearning interval was increased. #
Blood glucose and human memory
Psychopharmacology, 1993
As it has been suggested that blood glucose might play a role in the action of some cognitive enhancing drugs, the influence of glucose containing drinks on human memory was examined. In a double-blind study the influence was examined of a drink containing 50 g glucose, or a placebo, on the ability to recall a word list. There was a significant correlation between blood glucose values and the number of words recalled. Those whose blood glucose levels were increasing remembered significantly more words than those whose blood glucose levels were falling. No relationship was found between blood glucose and performance on a test of spatial memory. In a second study blood glucose levels were raised for 2 h by taking a series of glucose-containing drinks. The number of words recalled from a word list correlated significantly with blood glucose levels but not with recall of a Wechsler story. The glucose-induced improvement in memory did not occur only in those whose blood glucose levels were initially low; rather it occurred irrespective of initial blood glucose level.
Glucose effects on declarative and nondeclarative memory in healthy elderly and young adults
Psychobiology, 1997
Peripheral glucose ingestion enhances performance on explicit declarative verbal memory tasks in healthy elderly people. In the present experiment, healthy young and elderly adults were administered glucose (50 g) or saccharin followed by tests of declarative verbal memory (free recall and recognition of a word list) and a nondeclarative priming test (word-stem completion). In the elderly, glucose significantly enhanced performance on the declarative but not on the nondeclarative portions of the test. Performance by the young subjects was equivalent in the glucose and saccharin conditions. These fmdings, that glucose enhances memory for a declarative/explicit but not nondeclarative/implicit task, support the notion that declarative and nondeclarative memory systems are separate functional and anatomic systems.
Blood glucose influences memory and attention in young adults
Neuropsychologia, 1994
There is evidence from animal studies that increased blood glucose levels are associated with improved memory and attention. Although previous studies have found human memory to be facilitated by the administration of glucose, attentional measures have been largely ignored. Therefore the impact of a glucose drink, or a placebo, on the Rapid Information Processing Task and the Stroop Task was examined. The reaction times of those taking the Rapid Information Processing Task were faster both during the baseline period and after a glucose drink if the blood glucose values were high. With the Stroop task the ability to perform the most cognitively demanding sub-test was selectively enhanced if blood glucose values were increasing prior to starting the test. The ability to recall words from a word list was greater if a glucose drink had been consumed, although primacy and recency were not differentially influenced. The possibility is discussed that higher levels of brain glucose are associated with better memory and attention.
Glucose enhancement of performance of memory tests in young and aged humans
Neuropsychologia, 1989
Recent findings indicate that glucose administration enhances memory processes in rodents. This study examined the effects of glucose on memory in humans. After drinking glucose-or saccharin-flavored beverages, college-aged and elderly humans were tested with modified versions of the Wechsler Memory Scale. Beverages and tests were administered in a counter-balanced, crossover design, enabling within subject comparisons.