Some critics go after sucrose, and some go after fructose, but new research at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB) says it's all bad; daily consumption of beverages sweetened with high-fructose corn syrup or sucrose were shown to impair the ability to learn and remember information, particularly when consumption occurs during adolescence.

For the research, both adult and adolescent rats were given daily access to sugar-sweetened beverages that mirror sugar concentrations found in common soft drinks. Adult rats that consumed the sugar-sweetened beverages for one month performed normally in tests of cognitive function; however, when consumption occurred during adolescence the rats were impaired in tests of learning and memory capability.

Lead author Dr. Scott Kanoski from the University of Southern California, said, "It's no secret that refined carbohydrates, particularly when consumed in soft drinks and other beverages, can lead to metabolic disturbances. However, our findings reveal that consuming sugar-sweetened drinks is also interfering with our brain's ability to function normally and remember critical information about our environment, at least when consumed in excess before adulthood."

In 2010, Elyse Powell, psychology professor Bart Hoebel, visiting research associate Nicole Avena and graduate student Miriam Bocarsly of Princeton found that high-fructose corn syrup led to more weight gain than water sweetened with table sugar, even if calories are the same. The new work finds it's all bad for the brain. Photo: Denise Applewhite

In addition to causing memory impairment, adolescent sugar-sweetened beverage consumption also produced inflammation in the hippocampus, an area of the brain that controls many learning and memory functions.

"The hippocampus is such a critical brain region for memory function," says Kanoski. "In many ways this region is a canary in the coal mine, as it is particularly sensitive to insult by various environmental factors, including eating foods that are high in saturated fat and processed sugar."