According to the latest research, concentration drains glucose from a key part of the brains of young and old rats, but dramatically more from older brains, which need more recovery time... The research, detailed in two studies published in May, are part of research that may impact "how schools schedule classes and meals as well as our understanding of age-related deficits in memory and learning," said lead researcher Paul E. Gold of the University of Illinois. "The brain runs on glucose," said Ewan C. McNay of Yale University. "Young rats can do a pretty good job of supplying all the glucose that a particular area of the brain needs until the task becomes difficult. For an old rat given the same task, the brain glucose supply vanishes out the window. This correlates with a big deficit in performance. A lack of fuel affects the ability to think and remember."

Glucose is a naturally occurring sugar in the blood and the primary source of energy in human brain metabolism. Last year, Gold, a professor of psychology, and McNay made a significant impact when they reported "declines of hippocampal extracellular glucose concentrations in rates" as they went through a maze. Their finding challenged conventional thinking about levels and stability of glucose in the brain. It has been long thought that the brain always has an ample supply of glucose.

"While this is the case in terms of consciousness, the new findings suggests that glucose is not always present in ample amounts to optimally support learning and memory functions," said Gold, who is also the director of the Medical Scholars Program in the UI College Medicine at the University of Illinois at Urbana-Champaign.

In the May issue of Neurobiology of Learning and Memory, Gold and McNay reported that glucose drainage during a task is site specific. "Hippocampal extracellular levels fell by 30%, but in other brain areas remained stable. Only the part of the brain involved with what the animal is asked to do is affected by changes in glucose usage", Gold said. "This is not simply a reflection of changes in circulating blood levels or drainage in other areas."

Glucose enhances learning and memory not only in rats but in many populations of humans," said Gold. "For school children, this research implies that the contents and timing of meals may need to be coordinated to have the most beneficial cognitive effects that enhance learning.