Obesity Could Affect Learning and Memory, Research Finds

A new study found that obesity can harm the ability to remember and learn things.

Researchers from Princeton University's Princeton Neuroscience Institute study how obesity can affect brainpower. Published in The Journal of Neuroscience on Monday, the study revealed that rats who were obese couldn't complete obstacles as well as mice who were not obese because of rogue immune cells.

In America, 39.8 percent of adults are obese, according to the Centers for Disease Control and Prevention. That's about 93.9 million people in just the United States. Worldwide, about 600,000 million people are obese. Obesity is known to be related to conditions such as stroke, type 2 diabetes, heart disease and some cancers.

For this study, the scientists studied two groups of male mice: one that was fed a high-fat diet and weighed 40 percent more than mice who ate standard food, and another that was of normal weight. The obese rats weren't able to escape mazes as well as the non-obese rats, and they were less capable of remembering an object's location.

Microscopic knobs called dendritic spines sit on nerve cells and receive signals. The mice that were obese had fewer dendritic spines the part brain that is important for learning and memory, called the hippocampus. The dendritic spines loss was apparent in multiple parts of the hippocampus.

The dendritic spines are destroyed because the number of microglia, which are immune cells, increase around the nerve cell connections in obese mice. The researchers interfered with the microglia in the obese mice and found that the dendritic spines were protected and the mice started improving on their tests.

An aerial view shows visitors walking in a maze at a tourist resort in Zunyi, China. Mice who were obese were unable to complete mazes as well. STRINGER/REUTERS

Previously, scientists have found that obesity may contribute to Alzheimer's disease. A February 2018 study found that obesity may be a cause of Alzheimer's disease and recommended that obesity prevention and treatment could be a way to avoid the disease. Other studies have linked microglia with Alzheimer's disease, including one published in December 2017. The scientists found that microglial dysfunction is a contributing factor to the disease.

This research is beneficial because scientists could potentially create a way to stop microglia from damaging the dendritic spines, helping to protect humans against brain trouble that could be related to obesity, such as Alzheimer's disease. If they're able to stop the over-active microglia in humans like they were in mice, then there may be some treatment options. Even if the cognitive issues are unrelated to obesity, the research still may help scientists develop potential solutions.