Summary: Elevated levels of ghrelin, the stomach-derived hunger hormone, are associated with a stronger preference for smaller, immediate monetary rewards over larger, delayed ones.
Source: The Endocrine Society
New research shows that higher circulating ghrelin concentrations, a hormone produced in the stomach that stimulates appetite, predict a greater tendency to choose smaller immediate monetary rewards rather than larger rewards available after a delay.
The findings were presented at ENDO 2021, the annual meeting of The Endocrine Society, and provide human evidence that the hunger hormone can influence monetary decision-making and impulsive choice behavior.
Ghrelin acts as a signal to the brain that the body needs energy, and it is known to modulate neural pathways involved in reward processing. Levels of ghrelin rise and fall across the day in response to fasting, food intake and individual metabolism. Animal research has previously suggested that ghrelin affects impulsivity and reward-driven behaviors; this study extends those observations to human financial choices.
The research team, led in part by Franziska Plessow, Ph.D., assistant professor of medicine at Massachusetts General Hospital and Harvard Medical School, tested the relationship between circulating ghrelin and performance on a delay discounting task, a standard measure of impulsive decision-making. In delay discounting tests, participants choose between smaller amounts of money available immediately and larger amounts available after a specified delay; the tendency to prefer immediate, smaller rewards is taken as an index of impulsivity.
A total of 84 female participants, ages 10 to 22, completed the study. The sample included 50 individuals diagnosed with a low-weight eating disorder, such as anorexia nervosa, and 34 healthy control participants. All participants fasted prior to the study visit and then received a standardized meal. Blood samples were taken to measure total ghrelin both before and after that meal, and participants subsequently completed the hypothetical delay discounting choices—for example, deciding between receiving $20 today or $80 in two weeks.
Among healthy girls and young women in the study, those with higher ghrelin concentrations were significantly more likely to opt for immediate but smaller monetary rewards rather than wait for larger delayed amounts. This pattern indicates an association between elevated ghrelin and more impulsive monetary decision-making. According to Plessow, these results suggest that ghrelin may influence reward-related choices beyond its established role in appetite and food-seeking behavior.
Interestingly, the link between ghrelin levels and monetary choices was not observed in the age-matched group of participants with low-weight eating disorders. Individuals with such conditions are often described as having a form of ghrelin resistance—where higher hormone levels do not produce the expected biological or behavioral responses—and the absence of an association in this group may reflect a disconnect between ghrelin signaling and decision-making processes in the context of these disorders.
The study’s design—measuring hormone levels both before and after a controlled meal and administering a standardized delay discounting task—offers a direct test of how short-term fluctuations in a hunger-related hormone relate to economic choices in humans. While these results do not establish causality, they point to a broader role for metabolic signals in shaping non-food-related behaviors, including financial decisions that require weighing immediate versus delayed rewards.
Plessow emphasized that these novel findings should encourage further investigation into how ghrelin and other metabolic hormones influence perception, reward valuation and decision-making in people without eating-related pathology, as well as how altered hormone signaling in eating disorders might affect cognition and behavior more generally.
The research received funding from the National Institutes of Health and a Charles A. King Trust Research Fellowship Award to Dr. Plessow. Naila Shiraliyeva, M.D., a research fellow at Massachusetts General Hospital, presented the study findings at ENDO 2021.
About this neuroscience research news
Source: The Endocrine Society
Contact: Jenni Glenn Gingery – The Endocrine Society
Image: The image is in the public domain
Original Research: Findings presented at ENDO 2021