In 2018, a team of scientists from the aforementioned university published their research on the cognitive repercussions of interruptions in gut-brain communication, focusing on the vagus nerve, the longest of the cranial nerves, which mediate communication between the digestive system and the brain. When scientists disrupted this communication in animals during their research, they also compromised their ability to perform the proper feeding behavior, which they, of course, expected. They did not expect that this mechanism would also impair cognitive abilities, such as memory, which may indicate that the vagus nerve also plays a previously unknown role in memory function.
Consequently, more extensive research was needed that led scientists to a hormone called ghrelin. This is what is known as the famous hunger hormone, because it is responsible for regulating our eating behavior and, as suggested by the latest research, also several other, not related to food. During the tests, scientists focused on blocking ghrelin receptors in the gut, which communicate with the brain via the vagus technologi and as the author of the study, Scott Kanoski explains, this led to the expected results, namely, the animals ate more often, gained weight and began to have problems with glucose regulation.
However, the blockage did not make the animals overall eat more: "It doesn't seem to have affected how much they ate. Instead, they ate more often, so they ate more meals, and compensated for this by reducing meal size. It seems to us that this increased frequency of eating is related to memory impairment. Remembering the last time you ate affects how quickly you eat again. With our rats it was much faster - explains Kanoski. Interestingly, the animals did not forget where their food was, only that they had just eaten a meal.
This means the impairment of a particular type of memory called episodic memory, which is the memory that helps us remember our first day of school or what we ate for breakfast yesterday. In short, the link between ghrelin and memory is obvious, and scientists already have an idea of how to use it to treat patients, but as always in these types of cases, it takes a lot of time and resources, but in the future, the results of these studies may be important in the approach to dementia or age-related cognitive impairment.