Memory enhancement in elderly humans: effects of glucose ingestion

Recent findings demonstrate that, in rats, posttraining injections of glucose can enhance subsequent memory performance. The purpose of this study was to extend these findings to an elderly human population by testing the hypothesis that acute increases in peripheral blood glucose levels would enhance performance on memory tasks. Eleven subjects ranging in age from 58 to 76 years participated in the study. A within-subject, repeated-measures design was used in which each subject was tested under two different glycemic conditions: with fasting blood glucose levels and with increased blood glucose levels. Blood glucose was manipulated via consumption of beverages sweetened with either saccharin or glucose powder. After beverage consumption, subjects took four tests from the Wechsler Memory Scale. Comparisons of performance under the two glycemic conditions showed that scores were higher after the glucose beverage on narrative memory tests and the total Wechsler Scale. Nine of the eleven subjects had higher total Wechsler Scale scores. These results contribute to the growing evidence that glucose metabolism should be considered in the study of memory processes. The implications of such relationships for age-related memory deficits are discussed.