Brain reward system's alterations in response to food and monetary stimuli in overweight and obese individuals

Abstract

The brain's reward system is crucial to understand obesity in modern society, as increased neural responsivity to reward can fuel the unhealthy food choices that are driving the growing obesity epidemic. Brain's reward system responsivity to food and monetary rewards in individuals with excessive weight (overweight and obese) versus normal weight controls, along with the relationship between this responsivity and body mass index (BMI) were tested. The sample comprised 21 adults with obesity (BMI > 30), 21 with overweight (BMI between 25 and 30), and 39 with normal weight (BMI < 25). Participants underwent a functional magnetic resonance imaging (fMRI) session while performing two tasks that involve the processing of food (Willing to Pay) and monetary rewards (Monetary Incentive Delay). Neural activations within the brain reward system were compared across the three groups. Curve fit analyses were conducted to establish the association between BMI and brain reward system's response. Individuals with obesity had greater food-evoked responsivity in the dorsal and ventral striatum compared with overweight and normal weight groups. There was an inverted U-shape association between BMI and monetary-evoked responsivity in the ventral striatum, medial frontal cortex, and amygdala; that is, individuals with BMIs between 27 and 32 had greater responsivity to monetary stimuli. Obesity is associated with greater food-evoked responsivity in the ventral and dorsal striatum, and overweight is associated with greater monetary-evoked responsivity in the ventral striatum, the amygdala, and the medial frontal cortex. Findings suggest differential reactivity of the brain's reward system to food versus monetary rewards in obesity and overweight. Hum Brain Mapp 38:666-677, 2017. © 2016 Wiley Periodicals, Inc.

Disruption of Accumbens and Thalamic White Matter Connectivity Revealed by Diffusion Tensor Tractography in Young Men with Genetic Risk for Obesity

“…Given its complexity, its activity is closely associated to that of other main networks, such as the salience network, the emotional arousal network and the executive network (Gupta et al, 2015 ). Brain structural and functional connectivity changes in the reward system, closely resembling those observed in addiction (Michaud et al, 2017 ), have also been reported in obesity (Marqués-Iturria et al, 2015 ; Blechert et al, 2016 ; Carnell et al, 2017 ; Papageorgiou et al, 2017 ; Verdejo-Román et al, 2017 ), affecting several tracts (e.g., the anterior thalamic radiation, accumbofrontal fasciculus, forceps minor (FMi), cingulum, superior longitudinal fasciculus, inferior fronto-occipital fasciculus (Cho et al, 2013 ; Marqués-Iturria et al, 2015 ; Kullmann et al, 2016 ; Nangunoori et al, 2016 ; Papageorgiou et al, 2017 )) of the reward pathway (Sesack and Grace, 2010 ; Xu et al, 2012 ; Bracht et al, 2015 ; Yang et al, 2017 ). Only few studies, however, have investigated whether structural connectivity might be disrupted in people with genetic risk for obesity (Dennis et al, 2014 ; Spieker et al, 2015 ), reporting somewhat conflicting results.…”

Dorsolateral and medial prefrontal cortex mediate the influence of incidental priming on economic decision making in obesity

“…We used a two-sample t-test to investigate whether there were any between-group differences between priming conditions. Previous studies showed quadratic associations of responsivity to reward and the physiology of the reward system with BMI 20 , 39 – 42 . We therefore tested whether the cumulative priming effect was related to BMI 2 .…”

Lost in Translation? On the Need for Convergence in Animal and Human Studies on the Role of Dopamine in Diet-Induced Obesity

“…Food often comes at a cost, which requires weighing your options. Obese individuals may be less willing to, first, pay money for plain than highly palatable food items [73]; second, exert effort to obtain food or monetary rewards [66,166]; and third, wait for a larger reward if a smaller immediate reward is offered simultaneously, as consistently observed in delay discounting tasks ( [167][168][169][170], but see [51•]). Willingness to exert effort relies on regions in the affective loop and is particularly interesting because of its link to dopamine [171,172] as well as lowgrade systemic inflammation [173], which is highly prevalent in obesity (see Box 1).…”