High-fat diet can degrade your brain, cause cognitive impairment

One group of male mice was fed a diet wherein 10 percent of the calories are from saturated fat while the other group consumed 60 percent fat. But as mice become obese, their microglia become focused on overeating.

But it is not all bad news; the research also suggests that switching to a low-fat diet for 2 months can counteract the brain-damaging effects of a high-fat diet.

The findings reveal that when it comes to a high-fat diet, obesity isn't the only risk. The diets contained similar proteins and macronutrients. Researchers found that high-fat diets can cause active immune cells in the brain to become inactive and start consuming neuron connections.

According to the researchers, the diets the mice were fed represented a healthy diet versus a fast-food diet in humans.

During the fourth, eight, and 12th week of the experiment, the researchers assessed the weight, food intake, insulin level and blood glucose level of the two groups of mice. In addition to metabolic measurements, researchers also observed brain functioning like memory, center of learning, levels of synaptic markers, etc.

By 12 weeks, however, the mice fed a high-fat diet had not only become obese, but they also had reduced levels of synaptic markers and increased cytokine levels, indicating that synapses were being destroyed in the hippocampus. "What happens in obesity is they stop moving", explains Dr. Stranahan. "When they stop moving, they basically just sit there and start eating synapses". But by twelve weeks, the scientists began to see cognitive problems in the high-fat group.

"Dr. Stranahan notes that the findings suggest medications now used to treat Crohn's disease and rheumatoid arthritis - which work by blocking certain inflammatory cytokines, some of which were present in the brains of mice fed a high-fat diet - may show promise for neurological conditions involving synaptic loss, though further research is required". Going back to a low-fat diet will not get rid of the obese state, but it can wholly reverse the cognitive shrinking ability in the brain. "Microglia eating synapses are contributing to synapse loss and cognitive impairment in obesity", said corresponding author Alexis M Stranahan, from the Medical College of Georgia in the US. Despite the switch, their overall fat levels remained higher compared to the mice who didn't gain weight.