A new study shows that even a short-term diet of junk food can damage brain function permanently. "We know obesity causes inflammation in the body, but we didn't realize that [junk food] also causes changes in the brain," says study author Margaret Morris.
Researchers at the University of New South Wales in Australia discovered that rats fed high-fat, high-sugar diets had significantly impaired special memory skills after only one week compared to rodents given healthier diets. The junk food–fed rats weren't able to find objects that the researchers moved around, which was no problem for the other rats. Plus, these animals had inflammation around the hippocampus, the part of the brain that controls special memory.
The scientists were shocked at how quickly the unhealthy diets derailed brain function. "What is so surprising about this research is the speed with which the deterioration of the cognition occurred," Morris says. "Our preliminary data also suggests that the damage is not reversed when the rats are switched back to a healthy diet, which is very concerning."
Morris suspects these findings would extend to humans, especially older adults. "While nutrition affects the brain at every age, it is critical as we get older, and it may be important in preventing cognitive decline," she says.