Why you should never make a decision when you are hungry
RESEARCHERS at the Sahlgrenska Academy, University of Gothenburg, Sweden, have pinned down a hormone that is produced when we are hungry that interferes with rationality and decision-making. Rats given the hormone ghrelin were more likely to act on impulse. Impulsivity affects everyone to differing degrees, and each individual can be more or less impulsive depending on the situation.
Forgoing something pleasurable now, in favour of something better later on, shows control. This socalled delayed gratification is regarded as the opposite of impulsive behaviour. Impulsivity can be broken down into two types: Impulsive action, in other words, the inability to stop one’s self from making a physical action; and impulsive choice, an inability to delay gratification.
Although most people can control their impulses sufficiently, impulsivity is a major factor in a number of conditions, including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), eating disorders, and substance abuse. This connection to various psychiatric conditions makes impulsivity an important area of study. Earlier studies have uncovered a relationship between food reward behaviour and impulsivity. However, a mechanism has not yet been proven.
A new study, published recently in Neuropsychopharmacology, aimed to fill this gap. The researchers investigated impulsivity in rats, specifically in relation to the hormone ghrelin. Ghrelin is a hormone, produced in the gastrointestinal tract that acts on the central nervous system. It is released when the stomach is empty. Once the stomach has become filled, production of ghrelin ceases. Ghrelin readies the body for food, and it also works on cells of the hypothalamus to induce the feeling of hunger.
The role of ghrelin is not limited to the hunger response alone. It has also been implicated in the reward behaviour associated with drugs, alcohol, and food intake. Researchers at the Sahlgrenska Academy, led by Karolina Skibicka, set out to investigate ghrelin’s potential role in impulsive behaviour. The team trained rats to perform a variety of tasks that allowed them to measure impulsive behavior. The first, referred to as the “go/ no-go” test, measured the rats ability to restrain a response.
Rats were trained to either press a lever to get a reward - referred to as a “go” signal - or they were rewarded for not pressing a lever a “no-go” signal. The rats were taught to either “go,” or “no-go,” dependent on an auditory signal (a light or buzzer). A second trial, called the “differential reinforcement of low rate,” provided rats with a food pellet reward only if they were able to withhold their response for a set period of time. The third leg, called “delay discount,” measured the rats’ ability to delay gratification.