Sweet remembrances.

Sweet remembrances

Scientists hoping to promote better memory through chemistry say the simple sugar glucose provides some sweet clues. In fact, a drink of glucose-flavored lemonade markedly improves the performance of elderly volunteers on tests of long-term verbal memory, according to a report in the September PSYCHOLOGICAL SCIENCE.

Proper glucose regulation apparently plays an important role in verbal memory and possibly other types of recall, assert psychological Carol A. Manning of the University of Virginia in Charlottesville and her colleagues. For example, the researchers found that nondiabetic, elderly individuals who display unusually large jumps in blood glucose after consuming a glucose drink, indicating poor regulation, displayed the poorest verbal memories.

Manning and her co-workers recruited 17 healthy volunteers between the ages of 62 and 84. On two consecutive mornings, each participant entered the laboratory after fasting the previous night and drank and 8-ounce glass of lemonade sweetened with either glucose or saccharin. Blood glucose levels were monitored for the next 90 minutes while the volunteers took tests measuring memory, intelligence, attention and finger dexterity.

Glucose ingestion substantially enhanced scores on two tests of long-term verbal memory. On one test, participants listened to an audiotaped narrative passage and recounted the passage 5 minutes and 40 minutes later. On the other test, volunteers attempted to repeat a list of 12 words. Those who failed were given up to 11 more chances, and after each try an experimenter repeated those words they forgot.

The findings support a report published last year by the University of Virginia team noting glucose-stimulated verbal memory improvement among 11 elderly people, observes coauthor Paul E. Gold. However, he says, the ways in which glucose sparks memory remain unclear. Animal studies indicate that blood glucose increases improve the ability of cholinergic brain cells to transmit acetylcholine. This chemical messenger, involved in memory, may become less available as people age, Gold says.

Frequent glucose consumption presents dangers to the elderly -- such as increasing the risk of diabetes -- that discourage its use as a memory booster, Gold asserts. In future studies, the scientists plan to monitor blood glucose levels of elderly volunteers throughout the day, target specific glucose deficits and identify substances that reset glucose levels.