Key points:
- Rats that were fed a diet chock-full of fat and sugar in their adolescence suffered memory impairment later in life.
- The research focuses on a neurotransmitter called acetylcholine that is essential for memory and functions such as learning, attention, arousal and involuntary muscle movement.
- Memory damage in rats was found to be reversible with specific drugs.
A new study on rats that feasted on a high-fat, sugary diet raises the possibility that a junk food-filled diet in teens may disrupt their brains’ memory ability for a long time.
Prior research has shown a link between poor diet and Alzheimer’s disease. Those who suffer from Alzheimer’s disease tend to have lower levels of a neurotransmitter called acetylcholine that is essential for memory and functions, such as learning, attention, arousal and involuntary muscle movement. Researchers at the University of Southern California wondered what this could mean for younger people who had a similar diet, particularly during adolescence when the brain is undergoing significant development.
In the study, published in Brain Behavior and Immunity, researchers tracked the acetylcholine levels of a group of rats on a fatty, sugary diet by analyzing their brain responses to memory-testing tasks. The tasks involved letting the rats explore new objects in different locations. Days later, the researchers reintroduced the rats to the scene that was nearly identical except for the addition of one new object. Rats on the junk food diet showed signs they could not remember which object they had previously seen and where, while those in the control group showed familiarity.
“Acetylcholine signaling is a mechanism to help them encode and remember those events, analogous to ‘episodic memory’ in humans that allows us to remember events from our past,” said lead author and postdoctoral research fellow Anna Hayes. “That signal appears to not be happening in the animals that grew up eating the fatty, sugary diet.”
In another round of the study, the research team was able to reverse the memory damage using medication that induces the release of acetylcholine. When they injected two drugs—PNU-282987 and carbachol—directly into the rats’ hippocampus, memory ability was restored.
Study author Scott Kanoski, a professor of biological sciences, emphasized that adolescence is a very sensitive period for the brain when important changes are occurring in development.
“Unfortunately, some things that may be more easily reversible during adulthood are less reversible when they are occurring during childhood,” he said.