Scientists conducted an experiment on rodents. He showed that drinks with added sugar provoke memory problems associated with the hippocampus, and also helped to find a connection between specific changes in gut bacteria and impaired brain function.
Neuroscientist Scott Kanoski has studied the connection between nutrition and brain function for many years. His work showed that drinking sugary drinks impairs memory function in rats. And that those same drinks are altering the gut microbiome. Now he, along with scientists from the University of California and the University of Georgia, has found out if there is a direct connection between changes in the microbiome and memory. Details are published in the journal Translational Psychiatry.
Scientists have given adolescent rats free access to a sugary beverage similar to those found in humans. When the rodents became adults about a month later, the researchers tested their memory using two methods. One examined memory associated with the hippocampus, the other explored memory function controlled by the peripheral cortex.
It turned out that animals that consumed a lot of the sugary drink were more likely to have problems with the memory that uses the hippocampus. At the same time, sugar did not affect the memories created by the peripheral cortex.
The researchers then examined the gut microbiomes of the rats and found differences between those who drank plain water and water with sugar. The sugary drinkers had more populations of two specific gut bacteria, Parabacteroides distasonis and Parabacteroides johnsonii.
After the experiment, the researchers investigated whether Parabacteroides, without the aid of sugar, could affect memory function in rats. They transplanted bacteria grown in the laboratory into the intestines of young animals that drank only water. In rodents that received the bacteria, memory impairment was observed almost the same as in rats that consumed sugar. However, memory impairment was also observed in the perifocal cortex. This further proves that changes in brain function can in fact be caused by changes in the gut microbiome.
Finally, biologists studied the activity of genes in the hippocampus and compared rats who drank water with sugar, plain water, and those who were transplanted with bacteria. The gene activity was altered in both rodents who consumed the sweetened drinks and those who were transplanted with Parabacteroides.
The results of this study support a direct link between the gut microbiome and brain function at the molecular level. Going forward, the team hopes to determine if changing habits such as healthier diets and exercise can reverse the harm caused by increased sugar intake early in life.