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Objective: Functional magnetic resonance imaging (fMRI) was used to explore the brain substrates of decisions under risk in excess weight adolescents. Decreased activations of the brain regions signaling risk (orbitofrontal cortex [OFC], insula) were expected during anticipation of higher rewards and increased activations of the brain regions involved in reward processing (OFC, striatum) were expected after reward receipt in excess weight adolescents compared to normal weight controls., Design and Methods: Fifty-two adolescents (age range 12-17), classified in three groups as a function of BMI: obese (n = 21), overweight (n = 15), or normal weight (n = 16) performed the Risky-Gains task as described by Paulus et al. in the fMRI scanner., Results: Excess weight adolescents, compared to normal weight controls, showed decreased left insular and increased midbrain activations during anticipation of risky choices. In addition, excess weight adolescents showed increased activations of the inferior frontal gyrus, parahippocampus, thalamus, and posterior brain regions after reward receipt., Conclusions: Adolescents with excess weight showed reduced activations in brain regions signaling risk and increased activations in regions signaling reward during anticipation of decisions involving risk and reward. In addition, post-decision reward outcomes produced increased activations of regions involved in emotional salience in excess weight adolescents versus controls., (Copyright © 2013 The Obesity Society.)

Adolescent obesity is increasingly viewed as a brain-related dysfunction, whereby reward-driven urges for pleasurable foods "hijack" response selection systems, such that behavioral control progressively shifts from impulsivity to compulsivity. In this study, we aimed to examine the link between personality factors (sensitivity to reward (SR) and punishment (SP), BMI, and outcome measures of impulsivity vs. flexibility in--otherwise healthy--excessive weight adolescents. Sixty-three adolescents (aged 12-17) classified as obese (n = 26), overweight (n = 16), or normal weight (n = 21) participated in the study. We used psychometric assessments of the SR and SP motivational systems, impulsivity (using the UPPS-P scale), and neurocognitive measures with discriminant validity to dissociate inhibition vs. flexibility deficits (using the process-approach version of the Stroop test). We tested the relative contribution of age, SR/SP, and BMI on estimates of impulsivity and inhibition vs. switching performance using multistep hierarchical regression models. BMI significantly predicted elevations in emotion-driven impulsivity (positive and negative urgency) and inferior flexibility performance in adolescents with excess weight--exceeding the predictive capacity of SR and SP. SR was the main predictor of elevations in sensation seeking and lack of premeditation. These findings demonstrate that increases in BMI are specifically associated with elevations in emotion-driven impulsivity and cognitive inflexibility, supporting a dimensional path in which adolescents with excess weight increase their proneness to overindulge when under strong affective states, and their difficulties to switch or reverse habitual behavioral patterns.