Glucose enhancement of memory in elderly humans: an inverted-U dose-response curve.

In animals, enhancement of memory with glucose and many other treatments is characterized by an inverted-U dose-response curve. The present experiment examined the dose-response curve for glucose enhancement of memory in elderly humans. Using a repeated measures, counterbalanced, crossover design, the subjects (60-82 year olds) were tested on four sessions, separated by 1 week or more, for performance on the Wechsler Logical Memory Test after ingestion of a fruit drink sweetened with glucose (0, 10, 25, and 50 g) and saccharin matched to comparable taste. The findings indicate that glucose enhanced performance on this test in an inverted-U dose-response manner, with optimal enhancement obtained at the 25 g glucose dose. These findings provide further demonstration of glucose enhancement of memory in elderly humans and also describe an additional analogy between the characteristics of glucose enhancement of memory in animals and humans.