GLUCOSE, MEMORY, AND AGING

Circulating glucose concentrations regulate many brain functions, incl uding learning and memory. Much of the evidence for this view comes fr om experiments assessing stress-related release of epinephrine with su bsequent increases in blood glucose concentrations. One application of this work has been to investigate whether age-related memory impairme nts result from dysfunctions in the neuroendocrine regulation of the b rain processes responsible for memory. Like humans, aged rodents exhib it some memory impairments that can be reversed by administration of e pinephrine or glucose. In elderly humans, ingestion of glucose enhance s some cognitive functions, with effects best documented thus far on t ests of verbal contextual and noncontextual information. Glucose also effectively enhances cognition in persons with Alzheimer disease or Do wn syndrome. Although earlier evidence suggested that glucose does not enhance cognitive function in healthy young adults, more recent findi ngs suggest that glucose is effective in this population, provided the tests are sufficiently difficult. In college students, glucose consum ption significantly enhanced memory of material in a paragraph. Glucos e also appeared to enhance attentional processes in these students. Ne ither face and word recognition nor working memory was influenced by t reatment with glucose. The neurobiological mechanisms by which glucose acts are under current investigation. Initial evidence suggests that glucose or a metabolite may activate release of the neurotransmitter a cetylcholine in rats when they are engaged in learning. Consequently, the issue of nutrition and cognition becomes increasingly important in light of evidence that circulating glucose concentrations have substa ntial effects on brain and cognitive functions.