Experiment of the Week: Hunger hormone linked to learning disabilities

For many of us, exam time is synonymous with binge-eating time. Well, apart from making you fat, this could also affect your learning. A recent study completed at the Yale University School of Medicine shows that you could actually learn better on an empty stomach.

The Yale study has shown that the hormone ghrelin has a direct, rapid, and powerful influence on the hippocampus, the part of the brain associated with learning and memory. Ghrelin, produced in the stomach, was previously associated with growth hormone release and appetite. It is released primarily from stomach epithelial cells when the stomach is empty, and it binds to receptors in several areas of the body.

The research team, led by Tamas L. Horvath, chair and associate professor of the Section of Comparative Medicine at Yale’s School of Medicine, first observed that peripheral ghrelin can enter the hippocampus and bind to local neurons. It promotes alterations in connections between nerve cells in mice and rats. The changes in neural connectivity are linked to enhanced learning and memory performance.

In other words, the hunger hormone ghrelin can increase the number of nerve connections in the area of the brain where new memories are formed, thus enhancing it.

“Based on our observations in animal models, a practical recommendation could be that children may benefit from not overeating at breakfast in order to make the most out of their morning hours at school,” Horvath said in a Yale press release. “The current obesity epidemic among American schoolchildren, which to some degree has been attributed to bad eating habits in the school environment, has been paralleled by a decline of learning performance. It is however too early to speculate if hormonal links between eating and learning are involved in that phenomenon.”

High ghrelin levels or administration of ghrelin-like drugs could also protect against certain forms of dementia, because aging and obesity are associated with a decline in ghrelin levels and an increased incidence of conditions of memory loss like Alzheimer’s disease.

The researchers also say it might be possible to use the hormone to develop new drugs to combat impaired learning and memory, but warn that weight gain may be a side effect.

The study has provided an advantage by boosting memory skills during food searches when animals are hungry. Learning and memory may be enhanced by high levels of ghrelin during food deprivation because animals need increased cognitive skills to track down food sources.