The Role of Dopamine in Binge-Eating Disorders

    The food landscape has drastically changed within the last two million years. In this day and age, highly processed foods, foods high in fats, and foods high in sugar are readily accessible. As the food landscape continues to change, the obesity rate has increased, and it is now considered an epidemic. Obesity is often comorbid with depression, anxiety, compulsivity, and eating disorders (Fobbs, 2021). During the past few years, the percentage of people with eating disorders has remained steady, but the mortality rate of people with eating disorders has brought more awareness and has encouraged more researchers to explore the causes of eating disorders such as binge-eating disorders. 

    As Wambura Fobbs mentioned in her talk, food can be seen as not only a necessity but also a reward (Fobbs, 2021). Extreme “wanting” for the reward of hyper-palatable foods may play a major role in overeating. The dopaminergic projections from the ventral tegmental area (VTA) to the prefrontal cortex (PFC) and nucleus accumbens (NAc) are the most significant part of the unconscious “wanting” system. Dopamine has also been involved in binge-eating disorders, which are characterized by uncontrollable occurrences of excessive consumption of highly palatable foods (Novelle, 2018). Studies have found that people with binge-eating disorders have a reduced level of dopamine in the brain. This downregulation of dopamine in the striatum has been suggested to explain the theory of reward hyposensitivity. According to this theory, the decreased expression of the dopamine 2 receptor is a response to compensate for the overeating of palatable foods, and this reduced sensitivity could predict binge-eating (Novelle, 2018). So, as you can see, dopamine plays a very important role in binge-eating disorders.

    Binge-eating disorder is the most prevalent eating disorder, and it is more common in women than in men but why is this so? One of the reasons is that ovarian hormones in women have an inhibitory effect during the intake of food, but the normal inhibitory effect is disrupted during binge-eating episodes. A study performed on female rodents found that the estrogen metabolite may enhance binge-eating because of its interference with dopamine signaling (Norvelle, 2018). Another one of the reasons is that prenatal stress rewires neural circuits in female mice which leads to binge-eating (Norvelle, 2018). Now it makes more sense why women are more likely than men to suffer from a binge-eating disorder. 

    Although binge-eating is often associated with obesity, most people with binge-eating disorders have normal weights. This finding is in line with what Wambura Fobbs found at the end of her experiment where the mice would cycle between eating palatable food and chow. The mice would end up binge-eating the palatable food and undereating the chow, but they would not gain any weight (Fobbs, 2021). So, if a person doesn’t gain weight, then why is binge-eating so dangerous? Binge-eating can lead to adverse consequences like heart disease or type two diabetes. For these reasons, an in-depth understanding of what is happening in the brain of someone who has a binge-eating disorder is vital to figuring out the most effective treatment for them.

References

Fobbs, Wambura. (2021, December 7). Leveraging Neural Recording and Behavior to Better Understand How Diet Impacts Cognition (Live Zoom Presentation). Loyola University Chicago Neuroscience Seminar, Chicago, IL, United States.

Novelle, M., & Diéguez, C. (2018). Food Addiction and Binge Eating: Lessons Learned from Animal Models. Nutrients, 10(1). https://doi.org/10.3390/nu10010071