HERE'S food for thought: a hormone that triggers hunger might also improve learning and memory. Ghrelin is released by the stomach when it is empty and triggers hunger by binding to the hypothalamus, a part of the brain that controls appetite and metabolism. However, the hormone is also known to interact with the hippocampus, the seat of learning and memory.x-posted to ubergeeken
Tamas Horvath of Yale Medical School and his colleagues injected mice with extra ghrelin and found that they consistently outperformed ordinary mice in standard laboratory tests for memory and learning. "Ghrelin improved the animals' performance by 30 to 40 per cent," says Horvath. Post-mortems also revealed that the treated mice had better-developed brain structure, with around 30 per cent more brain cell connections.
In contrast, mice engineered to lack the gene for ghrelin consistently underperformed in the tests. When injected with the hormone their performance became normal (Nature Neuroscience, DOI: 10.1038/nn1656).
Although the discovery is surprising, it makes evolutionary sense, says Horvath. If an animal is hungry, it needs extra brainpower and ingenuity to find that vital next meal. "Perhaps the cognitive brain is a side-effect of hunger."
If ghrelin does the same thing in humans, it could eventually yield new treatments to stave off mental decline and diseases such as Alzheimer's.
Horvath's team has already begun experiments in people to see if ghrelin improves mental agility, and whether people are sharper if they are hungry. "If you've got a big intellectual workload in the morning, it might be worth skipping breakfast," says Horvath.