High-fat diets slim down learning

Science News, Nov 6, 2004

It's well accepted that eating a high-fat diet has numerous detrimental effects on the body from the neck down. Now, preliminary findings in mice suggest that a high-fat diet can also harm the brain.

Lih-Chu Chiou and her colleagues at the National Taiwan University in Taipei fed male and female mice either high-fat chow, with about 45 percent of calories from fat, or normal chow, with about 13.5 percent of calorics from fat. The researchers kept the mice on the diets for 9 to 12 months before killing the animals and examining thin slices of their brains.

The focus of the study was the hippocampus, a part of the brain associated with learning and memory. In slices from male mice fed a normal diet, repeated electrical shocks to the slices caused hippocampal cells to fire with a strong electrical pulse, a response that seems to cement new experiences into long-term memory. Hippocampal cells from male mice fed a high-fat diet responded to shocks with a significantly weaker electrical pulse, an indication that the high-fat mice had poorer memory and learning skills.

Supporting these results, other male mice on the high-fat diet scored lower than normal-chow males when trained to avoid stepping on an electrically charged platform and then tested on their memory of that experimenters' trick.

Interestingly, hippocampal sections from female mice on either diet responded much like those of normal-chow male mice, suggesting that a high-fat diet had no effect on learning and memory in the female brain. Chiou's team plans to perform further tests to elucidate why a high-fat diet might affect male and female brains differently.