Neurogenetic and Neuroimaging Evidence for a Conceptual Model of Dopaminergic Contributions to Obesity

Abstract

As the incidence of obesity continues to rise, clinicians and researchers alike are seeking explanations for why some people become obese while others do not. While caloric intake and physical activity most certainly play a role, some individuals continue to gain weight despite careful attention to these factors. Increasing evidence suggests that genetics may play a role, with one potential explanation being genetic variability in genes within the neurotransmitter dopamine pathway. This variability can lead to a disordered experience with the rewarding properties of food. This review of literature examines the extant knowledge about the relationship between obesity and the dopaminergic reward pathways in the brain, with particularly strong evidence provided from neuroimaging and neurogenetic data. Pubmed, Google Scholar, and Cumulative Index to Nursing and Allied Health Literature searches were conducted with the search terms dopamine, obesity, weight gain, food addiction, brain regions relevant to the mesocortical and mesolimbic (reward) pathways, and relevant dopaminergic genes and receptors. These terms returned over 200 articles. Other than a few sentinel articles, articles were published between 1993 and 2013. These data suggest a conceptual model for obesity that emphasizes dopaminergic genetic contributions as well as more traditional risk factors for obesity, such as demographics (age, race, and gender), physical activity, diet, and medications. A greater understanding of variables contributing to weight gain and obesity is imperative for effective clinical treatment.

Keywords: BMI; dopamine; genetics; obesity.

Figure 1

A conceptual model of weight gain leading to obesity. The spokes dividing the factors leading to obesity are composed of broken lines to indicate the interaction among them, similar to the model proposed by Ziauddeen, Farooqi, and Fletcher (2012). We altered the categories from the original model to reflect the information we have presented in this review as well as additional clinical observations that we have made. Additionally, we represented the outside of the wheel with another broken boundary to represent the influence that as-yet-unidentified factors could have on the outcome of weight gain leading to obesity. Adapted by permission from Macmillan Publishers Ltd: Ziauddeen, H., Farooqi, I. S., & Fletcher, P. C. (2012). Obesity and the brain: How convincing is the addiction model? Nature Reviews Neuroscience, 13(4), 279–286. Copyright 2012.